And Lubrication - American Radio History

Transcript

The how-to magazine of electronics... GIGO ROAO. Servicing &Technology AUGUST 19861$2.25 Are you being chased by an overheated boomerang? ainternunce and lubrication ILS OI11et1111eS it's hard t9,- go back for a scope! 60-MHz full-function field-service Attache Case Oscilloscope is so light and small it will be taken everywhere, every time. LBO -325 packs all the power and performaioe of a cumbersome. backbreaking. 60 -MHz workbench osci losccrpe Into an easy -to -carry, ultra compact, featherweight unit. Although its 31/2 -inch CRT is as big and Gear as screens on large field -service scopesLBO-325 weighs only 9 lbs. So it *won't weich field-:echnicians down. no natter how far afield they go! LBO -325 is so small it fils inside a 3 -inch deep attache case with room to spare for a multimeter, service manuals and some tools.The ideal full -function scope for a cramped work area or crowded bench Reduces the cost of service calls. Time is money. A scope left in the vehicle takes time to retrieve. One kept in the shop causes repeat service calls. The LBO -325 Attacf e Case Oscilloscope s so easy b carry and use, techs will take it eveywhere, every tine. And the tine saved translates into extra Drof is for years to corre. Outperforms all other portables: 60 MHz Dual channel ALT TIME BASE simultaneously displays main waveform and any exparced portion ALT TRIG for stable display of. 2 asynchronous signals Bright, sharp 12 -kV trace Large 31/2 -inch PDA CRT Illuminated grat cule Corr per ensive triggering TV-V and TV -H sync separators Variable trigger hold -oft Delay line shows sharp leading edges CH -1 output drives low -sensitivity instruments Measures only 3 x 9 x 113/s inches Weighs 9 lbs. Two-year warranty. Built tough to provide long use, LBO -325 is backed by Leader's 30 -year reputation for reliability and by factory service depots on both coasts. rnn uvv LBO -325 CRT is shown actual s ze. Call toll-free (800) 645-5104 In 1` Y State (516) 231.64Cí0 Request an evaluation sample, o ratest Test Instrume nt Casa og wit over 100 outstandirg products, tte na r e and adcress of your nearest "Select" Leader Distributor, or acdit.onal infor'natian. Forprofessionals who know LEADER the Instruments Cc peralion difference. 380 Oser Avenue Hauppauge, New York -1788 Regional Offices: Chicago, Dallas Los Angeles, Boston, Allanra In Canada cali Omnitronix Ltd. (514) 337-9500 For Information Circle (1) on Reply Card For Demonstration Circle (2) on Reply Card The Ultimate in Low-Cost The Equipment At last! Here is your opportun ty to take y`ur pick from a rev test equipment line that has all the features you need and moreand at a price that is ur:el evably low. MODEL 9340 Pocket sze, 31/2 -dici DMM with 20 megonm range and 10 megolr tUtiDEI 9670 input resstance tc 30,O1C0 µF Drg11a pacitance te; er covering 0.1 pF sae $44°° MODEL 3301 31/2 -digit hand-held DMM wit 0.25% basic accuracy and MODEL 9101 Compact VOM with 27 ranges, including a 100 megohm range -1 2,000-hojr battery life $29°° $ó9o° MODEL 9120 Analog %OM with 12 DC range and output A tack $3900 MODEL 9401 41/2 -digit, full function, hand-held DMM with .05% accuracy and MODEL 9370 31/2 -digit auoranging DMM with a nemory mode and data hold $129°° D 5% basic accuracy $5900 DC MODEL 97.01 digi-clamp M compact AC clamp -on volt-ohrrammeter with data hoc Mercer =lectronc.s vro_ucts reflect tie design and zuality standares estabi3t d D., Simpson Electric Company, an industry, ,rear_ and known worldwide for integrity eader for over and product excel In Stock...AvaIatsle Now! Stop in at your nearest distributor and see this new, comp ete line of Mercer test instruments. =or the name of the MERCER distributor in your area, call i312) 697-2265, or serd for our new line catalog. rte. ELECTRONICS Division of Simpson Electric Company 859 Dundee Avenue, Elgin, IL 60120-3090 (312) 697-2265 Telex 72-2416 Circle it (4) on Reply Card August 1986 Electronic Servicing & Technology 3 s The how-to magazine of electronics... GIGOTRODIO Volume August 1986 40 12 Horizontal and color problems in RCA Satellite receiving antennas CTC107 By Homer L. Davidson It's eulogies and R.I.P. for this and similar receivers when either the + 120V regulated supply or the horizontal -sweep circuit operates at reduced power. These areas are interdependent. By James E. Kluge Where TVROs are concerned, not all birds have wings, and not all dishes rate wolf -whistles. All satellite receiving systems, however, depend upon efficient antennas for satisfactory viewing. Page 22 Top-quality products, technical knowledge and a deft hand are requisite when maintaining electronic equipment. 22 Maintenance and lubrication electromechanical genies such as televisions, stereos, CDs and VCRs need only a little preventive maintenance; the trick is in knowing 30 Page 9 To capture any desired image from TV screen or videotape, press a button on this Digital Video Copier. By Sam Wilson Do you agree with those Technology 56 What do you know about electronics? Tests for low -frequency amplifiers - By Sam Wilson Departments: 6 8 9 10 39 39 55 60 62 64 & (Photo courtesy of Toshiba Corporation.) technicians who consider the Second Class FCC license test a real brain strain? This month's questions are representative of that test -a score of 50% is good. Electronic Servicing Are you being chased by an overheated boomerang? dissipation). when to stop. Test your electronic knowledge 48 By Joseph J. Carr, CET When equipment seems failure prone, returning as predictably as a boomerang, consider overheating as a probable cause (even when there has been a designing gesture toward heat By Conrad Persson Electronic and 4 6, No. 8 August 1986 News Editorial Technology Feedback Literature Books Photof act Products Reader's Exchange Audio Corner Tests that permit checking frequency response quickly are useful for troubleshooting an amplifier that previously gave a good performance, but now is undependable. can even earn your Associate in Applied Science Degree in Electronics Engineering Technology. Of course, you set your own pace, and, if you ever have questions or problems, our instructors are only a toll -free phone call away. e first step is yours. To find out more, mail in the coupon below. Or, if you prefer, call toll-free 1.800.321.2155 (in Ohio, 1-800-523-9109). Well send you a copy of CIE's school catalog and a complete package of enrollment information. For your convenience, we'll try to have a representative contact you to answer your questions. CIE MAKES THE WORLD OF ELECTRONICS YOURS. Today's world is the world of electronics. But to be a part of it, you need the right kind of training, the kind you get from CIE, the kind that can take you to a fast growing career in business, medicine, science, government, aerospace, communications, and more. ecialized training. You learn best from a specialist, and that's CIE. We're the leader in teaching electronics through independent study, we teach only electronics and we've been doing it for over 50 years. You can put that experience to work for you just like more than 25,000 CIE students are currently doing all around the world. tactical raining. 4K RAM Microprocessor Training Laboratory, for example, trains you to work with a broad range of computers in a way that working with a single, stock computer simply can't. rsonalized training. You learn best with flexible training, so we let you choose from a broad range of courses. You start with what you know, a little or a lot, and you go wherever you want, as far as you want. With CIE, you CIE ES -11 Cleveland Institute of Electronics 1776 East 17th St., Cleveland, Ohio 44114 YES! I want to get started. Send me my CIE school catalog including details about the Associate Degree Program. I am most interested in: television/high fidelity service computer repair medical electronics telecommunications broadcast engineering robotics/automation other Print Name You learn best with practical training, so CIE's Auto-Programmed® lessons are designed to take you step-by-step, principle-by-principle. You also get valuable hands-on experience at every stage with sophisticated electronics tools CE-designed for teaching. Our Apt. Address City Age State Zip Area Code/Phone No. Check box for G.I. Bulletin on Educational Benefits MAIL TODAY! Veteran Active Duty ORCALL TOLL FREE 1-800-321-2155 (In Ohio, 1-800-523-9109) Circle (5) on Reply Card represents a "strengthening of HCPA's position as a manufacturer of consumer electronics workforce in Anaheim as well as its purchases of U.S.-made components for the new manufacturing line." goods... HCPA hopes to expand its Estimated household penetration by product (AS OF JANUARY 1986) Hitachi to produce VCRs in U.S. Hitachi announced that its whol- ALL TELEVISION COLOR TV MONOCHROME TV PROJECTION TV ly owned subsidiary, Hitachi Con- sumer Products of America, (HCPA) has begun VCR production in Anaheim, CA. Hitachi is the first company to produce VCRs in the United States. HCPA initially will produce 100,000 VCRs per year at its Anaheim plant. The plant currently annually produces 140,000 color TV sets and 60,000 projection TV sets. The company invested about $1.5 million in setting up the VCR production facilities. "Expansion of VCR production in the United States is an integral part of our international strategy in the consumer electronics field," said Shoei Yashima, senior executive managing director and chief of consumer products operations at Hitachi in Tokyo. Kazumitsu Minami, president of Hitachi Consumer Products of America, said the production of VCRs in the United States EIEOTROAiO Servicing &Tedvrdogy Editorial, advertising and circulation correspondence should be addressed to: P.O. Box 12901, Overland Park, KS 66212-9981 (a suburb of Kansas City, MO); (913) 888-4664. EDITORIAL Nils Conrad Persson, Editor Carl Babcoke, Consumer Servicing Consultant VCR HOME COMPUTERS AUDIO SYSTEMS COMPACT - -COMPONEN COMPACT DISC PLAYERS TELEPHONE ANSWERING DEVICES CORDLESS TELEPHONES HOME RADIOS Two up-and-coming classifications are not included in this list because they are still relatively new on the consumer scene: camcorders and cellular telephones. Camcorders represent a new breed of portable VCR; it is the combination camera -recorder that has replaced 2 -piece camera/ recorders in popularity. Now available in Beta, VHS and 8mm formats, camcorders were tracked BUSINESS Cameron Bishop, Group Vice President Eric Jacobson, Publisher Stephanie Fagan, Promotions Manager Kelly Hawthorne, Promotions Coordinator Dee Unger, Advertising Supervisor 75% separately from video cameras for the first time in 1985 sales: Approximately 400,000 were purchased last year. Cellular telephones are in demand for business use, but still are too expensive for most consumers. As the number of areas increases where cellular radio services are offered and as sales rise, pricing is expected to decrease to consumer affordable levels. OM, ELECTRONIC SERVICING & TECHNOLOGY is the "how-to" magazine of electronics. It is edited for electronic profes- sionals and enthusiasts who are interested in buying, building, installing and repairing consumer electronic equipment. This includes audio and video equipment, microcomputers and electronic games. ADMINISTRATION R. J. Hancock, President John C. Arnst, Circulation Director Jo Ann DeSmet, Circulation Manager Dee Manies, Reader Correspondent Marjorie Riggin, Associate Editor Joy Culver, Editorial Assistant Darryl) Fortune, Editorial Assistant Sandra D. Williams, Editorial Assistant SUBSCRIPTION PRICES: one year $18, two years $30, three years $38 in the USA and its possessions. Foreign countries: one year $22, two years $34, three years $44. Single copy price $2.25: back copies $3.00. Adjustment necessitated by subscription termination to single copy rate. Allow 6 to 8 weeks delivery for change of address. Allow 6 to 8 weeks for new subscriptions. Member, Audit Bureau of Circulation PHOTOCOPY RIGHTS: Permission to photocopy for internal CONSULTING EDITORS or personal use is granted by Intertec Publishing Corp. for Homer L. Davidson Christopher H. Fenton Bud Izen MP Victor Meeldijk Kirk G. Vistain Sam Wilson Member, American Business Press Member, Electronic Servicing Dealers Association ART Kevin Callahan, Art Director Tim Lynch, Graphic Designer Electronic Servicing & Technology 50% Source: "Consumer Electronics Annual Review," EIA/CEG Dan Torchia, Group Managing Editor 6 25% o 98% 92% 65% 3% 30% 15% 88% 51% 39% 2% 10% 12% 98% 100% libraries and others registered with Copyright Clearance Center (CCC), provided the base fee of $2 per copy of article is paid directly to CCC. 21 Congress St., Salem. MA 01970. Special requests should be addressed to Eric Jacobson, publisher. ISSN 0278-9922 $2.00 + 0.00 i/NTERTEt` PUBLISHING CORPORATION 1986 All August 1986 rights reserved. How to beat the high cost of cheap meters. Irudnuluu/ 0 10 You get what you pay for. So get the Fluke 70 Series. You'll get more meter for your money, whether you choose the affordable 73, the feature -packed 75 or the deluxe 77. All of them will give you years of performance, long after cheaper meters have pegged their fishhook needles for the last time. That's because they're built to last, inside and out. So they're tough to break. They don't blow fuses all the time. You don't even have to replace batteries as often. lam/raval And they're backed by a 3 -year warranty. 30 20 ó , Not the usual 1 -year. Of course, you may :,rc,,, ...;: only care that the world -champion 70 Series combines digital and analog displays with more automatic features, greater accuracy and easier operation than any other meters in their class. You may not care that they have a lower overall cost of ownership than all the other "bargain" meters out there. But just in case, now you know. For a free brochure or your nearest distributor, call toll -free 1-800-227-3800, ext. 229. FROM THE WORLD LEADER IN DIGITAL MULTIMETERS. FLUKE 73 FLUKE 75 FLUKE 77 $79 $99 $13 Analog/digital display Analog/digital display Analog/digital display Volts, ohms, 10A, diode Volts, ohms, 10A, rnA, Volts, ohms, 10A, mA lest diode test diode test Autorange Audible continuity Audible continuity 0.7% basic dc accuracy Autorange/range hold 'Touch Hold' function 2000+ hour battery life 0.5% basic dc accuracy Autorange/range hold 3 -year warranty 2000+ hour battery life 0.3% basic dc accuracy 3 -year warranty 20(10+ hour battery life 3 -year warranty ' Multipurpose holster Suggested U.S. list price, effective November 1,1985 Patent pending. FLUKE John Fluke Mfg Co. Inc. PO Box C9090, M/S 250C. Ecereh. WA 98206. Sala: (21)6) 356-5400 Other 1206) 347-6100 EUROPEAN HEADQUARTERS- Fluke (Holland) BV PO Box 2269 5600 CG 0ndheven She Netherlands 11401458045. OLA 51846 Ad No 4714-70 Inc. All nets reserved (c-) Coiyr,9hi 1985 John Fluke Mfg Co IN THE U.S. AND NON -EUROPEAN COUNTRIES. August 1986 Circle o (6) on Reply Card Electronic Servicing & Technology 7 Editorial Feedback on "Feedback" In the July 1986 issue of Electronic Servicing & Technology, we reinstated a department that we formerly published: our "Feedback" department (letters to the editor). I really don't have any explanation of why we discontinued it; it just fell by the wayside. And that's too bad, because we find letters from readers to be immensely helpful, and many of them deserve to be shared with other readers. Some of the letters we receive are complimentary. We like those, naturally. For example, there are those letters from readers who have found a particular article to be not only interesting and informative, but that actually has provided specific information useful in correcting a problem which previously had been unsolvable. We really can't say that we like to receive uncomplimentary letters: letters that point out that we've made an error in an article, or that we made reference in the text to a figure that was seven pages away from the text that described it, or that we left it out altogether. And we really don't like to receive letters that suggest that we have been misconstrued. For example, last month's Feedback contained a letter from a gentleman who felt that an editorial in an earlier issue suggested that we viewed servicing technicians as "reckless" (that's not at all the case). No, we don't like to receive letters like that, but we're glad that you send them. It tells us that you're reading the magazine carefully and that you care deeply enough about what we publish to try to correct us when we're in error. And it lets us know when we've in fact made an error, or haven't made ourselves clear so that we can correct the error or clear up the misconception. And other kinds of letters are helpful too. There's one in this month's Feedback department that provides information and suggestions supplementing Joe Carr's article, which appeared in the February issue of ES&T, entitled "Splish, Splash," on salvaging water damaged electronics products.Some of your letters suggest specific articles that you'd like to see us publish. While we can't promise that we'll be able to fulfill specific article requests, we'll certainly give serious consideration to any such requests that we receive. It is, however, entirely possible that a request by one of our readers will be used as an idea for an article. After all, the technicians who are working every day on sick electronic products know better than we do what kind of information they need. So, if you have something to say to the editors of ES&T, to any of our writers, or to other readers, write. Who knows, your letter might help other readers, or even yourself. This seems like a good place to state ES&Ts editorial policy about letters from readers. Any and all letters addressed to ES&T, or to any of ES&Ts writers concerning subject matter published in ES&T, are considered by the editors to imply consent by the writer to publish the contents of those letters in ES&T, including the name and city of residence (not only in the Feedback department, but in any article or other department). However, if you wish to write to anyone connected with ES&T and not have your comments published, simply tell us that you don't want your letter published and we will honor your request. But we would like to hear from you either way, so write. Make instant color prints from your TV screen with the Digital Video Copier This new device electronically produces vivid color prints directly from images on a TV screen or videotape. Developed by the Toshiba Corporation of Japan, in cooperation with the Polaroid Corporation, USA, the Digital Video Copier combines the photographic technology of Polaroid with Toshiba's digital memory technology. The prints show remarkable resolution, according to reports; brightness, contrast, hue and chrominance can be adjusted as desired while the image is frozen on the display screen. Toshiba foresees a broad range of applications where it is important to capture images: from dataprocessing equipment, medical equipment, computer graphics and office equipment as well as for storing TV/broadcast information and obtaining hard copy of video camera images. The system can be operated with the touch of a button. It incorporates just three main com- ponents: a video signal memory circuit, a 3.5 -inch picture tube and an instant camera that uses Polaroid's 3" x 4" instant color film. When the VIDEO COPY button is pressed, the TV image is captured instantly and stored in the digital memory circuit. The digital memory circuit can store 1.34Mbits of information: 256K x 5 plus 64K x 1. The stored image is resolved into its three primary color components, red, green and blue, which are converted separately back into analog signals. These are then displayed sequentially on a B&W CRT. An RGB filter is rotated in synchronization with this sequence, exposing the three primary colors onto the film. (See diagram). The reportedly perfect color registration is achieved because all three primary colors are exposed at exactly the same place on the film, causing no color -shear errors. Because of the high -capacity digital memory and sophisticated microprocessor, each picture element can be reproduced with 128 gradations, offering vivid, accurate photographs from picture signals in the NTSC TV format, or RGB signals that come directly from a personal computer. Heretofore, photographs of images on TV screens could only be made by photographing the TV screen with a camera, or by making a hard copy of the digitized picture signal, using a thermal transfer printer. Neither method was totally satisfactory. Soon to be released: a special 35mm camera that can reproduce TV pictures on conventional film, making it easy to produce multiple prints or slides. 3.5 -INCH B&W CRT VIDEO SIGNAL INPUT VIDEO SIGNAL MEMORY CIRCUIT DIA DECODER ..- í- RG CAMERA B FILM RGB FILTER WHEEL SHARPNESS HUE RGB INPUT R Figure 1. CHROMINANCE BRIGHTNESS CONTRAST This diagram shows the principles of the Digital Video Copier. (Diagram courtesy of Toshiba Corporation.) August 1986 Electronic Servicing & Technology 9 Water -damaged equipment Read with interest the article by Joseph J. Carr CET on page 49 of your February issue concerning water damage. I had experience with this problem twice on board ship during my service as a U.S. Navy officer. Each time, we were able to save all of the equipment. Both times, the equipment stood in sloshing salt water for several hours during rough weather. I had the electronics technicians working for me remove the covers and cases from the equipment and then had one man get in the shower and wash and flush everything out in a warm shower. Since the fresh water on board ship is distilled at sea we have very good water to use. We then took everything to the galley and dried it all in the bake ovens at low heat and good air circulation. From my own experience, I agree completely with Mr. Carr's article. Where distilled water is not available, care must be exercised in the use of faucet water due to possible hard water scale deposits. Softened water also may cause problems. Sometimes you run across a chassis covered with oily dirt and fuzz. These can be cleaned by dunking in a mixture of about eight ounces to 10 ounces of household ammonia, four ounces to six ounces of Mr. Clean, Lysol cleaner, or Murphy's oil, four ounces to six ounces of acetone and enough distilled water to make up a gallon. If the chassis is too big to submerge, use a small sprayer like an old dental "Water Pik" to hose it off. Wash with distilled water and dry for four hours to five hours in an oven set at 140°F to 150°F. All mechanical bearings, switches, etc., must be relubricated with the appropriate lubricant. Another bit of information that may be useful. Over a period of years I had several transformers overheat and asphalt-flood some of 10 Electronic Servicing & Technology the components and tube sockets. We removed the asphalt very easily by chilling it with dry ice from a CO2 fire extinguisher. The asphalt became brittle and flaked right out with the use of some dental tools. Roy A. Norman LCdr USN Ret Brunswick, GA A very special compliment Ever since I have been receiving issues of ES&T, I really enjoy reading them. In fact, ES&T is extremely interesting! Of course, I have read other electronics magazines but they really did not have the kind of interest that I was expecting. Interest such as: advanced, high -quality advertisements (digital test equipment, for example), tips on repairing televisions, using schematics diagrams; quizzes to read and to expand my memory with even more knowledge - this, and much, much more is what I pick up from this magazine. Speaking overall, I pick up a lot of good information from this magazine, but this is what I was searching for: an advanced learning electronics magazine. And that is why I love reading ES&T. It does two special things for me: It sharpens (or expands) my knowledge and brightens my interest. Thank you. Robert Posner Brooklyn, NY To: M.B. Danish, Aberdeen P.G., MD Thank you very much for your note regarding answers to "Test Your Electronic Knowledge" in the January 1986 issue of ES&T. The answer should have been D - not C as given on page 59. No matter how hard I try to avoid mistakes like this, they sometimes get through because of misprints or typing errors. In reference to the Gain/bandwidth relationship, it is always true that a shorter rise time represents a wider bandwidth. I am always grateful to readers for taking the time to send their comments. Thank you very much. Sam Wilson Letter to Sam Wilson: This letter is in reference to your article "Capacitors and Triggers" in the March 1986 ES&T. First, I want to say that I have enjoyed your books and articles for many years. The transistor parameter gamma [-y} is pretty obscure, alright. Your article brought it to mind after many years. Gamma is defined as the common collector current gain. y= 0 0 IE V,,e constant IB It also equals B+ 1 and And thank you, sir. Ed. 1 1-a CET confusion? A "News" article appearing in the May issue does nothing to clear the confusion over CET exams. The next -to -last paragraph hardly makes any sense at all. First a statement from the U.S. Copyright office, then a thoroughly confusing statement that technicians understand whether the CET is recognized by ISCET. So what? Must a degree from one university be recognized by another to be I looked in a lot of my material and only found it mentioned in the following: "Basic Electronics Vol. I," U.S. Navy training manual NAVPERS 10087-C. This also is available n a DOVER Publishing Company reprint. Terry L. Stivers valid? Also to Sam Wilson: Just a short note to let you know how much my Vocational students and I have enjoyed your articles over the years. Your articles are required reading.... Robert P. Saunders Vocational electronics instructor John Adams High School South Bend, IN journalistic fairness, a statement should be printed to inform readers of ETA -I's equal ability to grant CET certification, as well as any other organizations so authorized. I think in all J Larsen 60835 N. Hwy 50 Montrose, CO 81401 August 1986 Electronics instructor ITT Technical Institute St. Louis, MO Get, ECG Thermal Cut -Offs ECG Dual and Quad Head Assemblies for VCRs Made-to-Match Wrenches for VCRs ECG Those special adjustment requirements on VCRs have finally met their match. Philips ECG offers 8 special wrenches designed to match the configuration of the recesses that adjust tape feed, tape tensions and other functions. Industrial equipment should be protected from temperature overload, as well as current overload. Philips ECG Thermal Cut -Offs are fuses that react to temperature, instead of current, to prevent equipment from overheating. The thermal cut-offs offered by Philips ECG operate within a tolerance of +0 and -4 degrees Celsius of their nominal value. They are available in 20 temperature values ranging from 66°C (151°F) to 240°C (464°F). Made -to-match for both VHS and Beta units, there are VHS wrenches for tape feed guide, tape tensions, control head and control head phase, plus audio head and audio head phase. While for Beta, wrenches are for the audio and control heads. One tape transport adjuster wrench works on both VHS and Beta. Philips ECG has also simplified and speeded up the diagnosis and repair of torque problems in VCRs. Torque Meter Cassettes for PLAY and FAST-FORWARD/REWIND, for both VHS and Beta VCRs, give you a fast and accurate diagnosis of the problem. Philips ECG offers a high-quality line of drop -in replacement heads for both VHS and Beta VCR equipment. Included in the new line are dual and quad heads for VHS, and dual heads for Beta VCRs. Because they equal or surpass original manufacturer's specifications, these Philips ECG heads can be used to replace the heads in VHS units sold by Curtis Mathes, GE, Penney, Magnavox, Panasonic, Philco, Quasar, RCA, Sylvania, Altai, Hitachi, JVC and Mitsubishi. Beta heads are available for VCRs by Marantz, Toshiba, Sony and Zenith. When you have to replace a head, just check out the replacement you need in the comprehensive cross-reference section in the Philips ECG Audio and Video Brochure, or call your local Philips distributor. You'll find a replacement head that fits and works, fast. Circle 000 on the reply card. Circle 000 on the reply card. Common applications: All types of heaters, cookers and distilling apparatus as well as motors for fans, drills, saws, tools, coffee pots and hairdryers. Circle 000 on the reply card. Digital Multimeter ECC Another way to program extra profits into your TV/VCR No need to read between the lines with this accurate DM -25 Multimeter. The parameter value appears on the 31/2 -digit LCD readout. One of a new line of meters for service technicians being offered by Philips ECG, the DM -25 can be carried easily in pocket or tool box. In spite of its small size, the DM-25 has 14 ranges: DC voltages from lmV to 1000 Volts in 4 ranges. DC current from 2000 microamps to 2000 milli amps (2 amps) in 4 ranges. AC voltages to 750 VAC on 2 ranges. Resistance from 1 Ohm to 2 Megohms in 4 ranges. Basic DC accuracy is ±0.5%. Input impedance is 10 Megohms on DC and 4 Megohms on AC, to prevent overloading the circuit under test. The input has overload protection on all ranges. No need to fear hooking it up backwards, as it has an auto -polarity feature. Not only do you get 2000 hours of operation from a 9 Volt alkaline battery, you also get a warning flag when the battery life is down to 10%. In addition, the DM -25 comes with carrying case, battery, test leads and instruction manual. It's one of the five new multimeters being supplied by Philips ECG. For more information, see your local Philips ECG distributor, or circle the reader service card number. Circle 000 on the reply card. service calls. Now you can replace defective remote control transmitters. Our replacement Remote Control Transmitter is a good deal for your customer. It's a good deal for you, too. You get the extra profit and the extra convenience of just 71 Philips ECG RCTs that cover hundreds of TV/VCR models and chassis. And they're easy to find in our crossreferenced Philips ECG Remote Control Guide. It's the same happy story with a whole range of electronic replacement parts from Philips ECG. There are hundreds of Philips ECG distributors, nationwide, who offer you fast service on over 3,600 different ECG devices that replace more than 227,000 industry types. All meet or exceed JEDEC specs. From RCTs to microprocessor ICs, your Philips distributor has your replacement part. He'll put it in your hands fast. He also has a copy of the new Philips ECG Remote Control Guide, as well as other manuals and reference books that help you find the right part. If you can't find a Philips ECG distributor in your local yellow pages, let your fingers do the talking and punch up the toll-free number for information on replacement parts or reference books. 1-800-225-8326 If it's ECG, it fits. And it works. PhilipsECG A North American Philips Company J1edir,4d/o farell QJiciecp9 rorrlfàe¢lyr Geld ,nce. Horizontal and color problems in RCA CTC107 Technicians save time by remembering what service procedure worked well before with another receiver of the same model. The same components tend to fail in many receivers of the same brand and model. Davidson supplies that type of information for the 13 -inch RCA CTC107 model. By Homer L Davidson tor. A lack of voltage hints at an No sound-no raster In our experience, the horizontal In general, these symptoms open circuit or a malfunctioning output and color -output stages in the RCA CTC107 have accounted might indicate dead horizontal, SCR -regulator circuit. Next, for most service problems. Those dead power supply, failure to switch off the ac power and check two areas are featured in this start-up or a start-up followed in- in-circuit the forward and reverse stantly by shutdown. It is helpful conditions of the Q412 transistor article. Photofacts 1969-2, 2032-2 and and a good time -saving, trouble- and the CR405 damper diode. For 2104-1 cover the various versions shooting technique to determine forward conductions, use the diode of the CTC107A and CTC107C. All first whether the problem primari- test to measure the voltage drop are 13 -inch table models. Many of ly is in the power supply or in the across solid-state junctions. As the tips and suggestions about the horizontal -deflection system. With shown in the picture (with positive CTC107 can be applied also to ac power applied, attempt to meas- probe grounded and negative to RCA CTC108 and CTC109 models. ure the collector (case) do voltage the output -transistor case), the of Q412 horizontal -output transis- damper forward conduction has Review The RCA CTC107 is one of the many models that cannot operate unless both the + 120V regulated supply and the horizontal -sweep circuit are operating at almost full power. If the horizontal is dead, the + 120V regulator will not operate. If the + 120V regulator is dead, the horizontal will not operate. In both cases the receiver is totally dead. (In normal operation, the + 120V SCR regulator is kickstarted long enough to start the horizontal, etc.) No detailed description of this operation will be given here. See my last article for an explanation about SCR regulators. An X-ray safety circuit is designed to shut down the horizontal sweep (stopping all operations) if the high voltage is excessive or the picture tube current is excessive. That circuit is explained later. CR405 damper diode's forward -biased conduction is measured by grounding the Notice, however, that shutdown The positive probe and connecting the negative meter probe to the horizontal output from excessive high voltage transistor's case (collector). By the solid -state -junction voltage -drop method, the mimics a failure to start-up. diode tested 0.496V, which is average for dampers. With the positive meter probe on As in all troubleshooting, keep in the base, touch the negative probe first to the emitter and then to the collector. (The reading will be a near short in -circuit because of the low -value base mind that a heavy short in one cir- base/emitter resistors.) Reverse the polarity of the damper -diode test, and the base/collector test cuit might cause damaged compo- should show an OL overrange condition. Change to the ohmmeter function and nents in the power supply or other check for reverse -voltage leakage. If the results are not clear, remove Q412 for out -of circuit tests. associated circuits. - - 12 Electronic Servicing & Technology August 1986 produced 0.495V, a normal reading. With the test lead polarity reversed, two tests are necessary using the positive probe to the base and the negative probe, first to the collector and then to the emitter. When made on a transistor externally, the readings should be between 0.55V and 0.6V, but in circuit the paralleling resistances, particularly between base and F101' SA RF101 2.5 10W 5420' L101 120"JAC A/ CR103= CR101 R 4 42.-+162V 1 =CR102 L1C5 ÌCR104 .i emitter, might reduce those readings. If the readings are questionable, the transistor should be removed and tested out of circiut. Leakage readings are taken by using reversed -polarity higher ranges of the low -power ohmmeter, and should show a minimum of several megohms for these reverse -biased junctions. Lower readings are causes for suspicion. The preceding tests around Q412 should have located the most obvious causes of excessive current to the horizontal -sweep system, but in this case there was nothing malfunctioning. Therefore, the next step is to examine the SCR regulator and its low voltage source. The SCR regulator and dc power - No do voltage was measured at the SCR101 anode (case), although a normal reading is + 161V. This indicated a major defect in the low voltage + 162V unregulated supply (Figure 1). Arrows on the schematic show the components that are most likely to fail or suffer damage from the failure of other components. In this case history, two of the bridge diodes had developed severe leakage, blowing fuse F101 (5A) and opening surge resistor RF101. Incidentally, the separate bridge diodes can be tested with ohmmeter and diode junction tester without removing them from the circuit. Use 3A diodes as replacements when new ones are needed. After all known -defective components of the + 162V supply have been replaced, use care to avoid ruining them a second time by any serious overload that has not yet been found or corrected. One solution to questions about the SCR regulator is to eliminate it during a few tests. First, remove SCR101 for out-of-circuit resistance tests. A low reading of about 100Sí between gate (G) and cathode OS Cl Ì600µF COMPONENTS WITH ARROWS MIGHT BE DEFECTIVE CTC107 low -voltage circuit Figure 1. Arrows point out diodes CR101 through CR104 and C105 as components likely to fail and blow fuse F101 and resistor RF101, also identified by arrows on this schematic of the RCA CTC107 low-voltage power supply. Use the solid -state -junction voltage -drop diode test and the regular ohmmeter ranges to check leakages in the bridge diodes CR101, CR102, CR103 and CR104. +162V 9-4162V C105, TEST LEAD 600NF` +120V +161V SCR101 TEST LEAD A, +120V SOURCE VOLTAGES SHOWN HERE ARE FOR CORRECT OPERATION, NOT FOB THIS TEST CONDITION. Testing the CTC107 regulation Figure 2. A continuously operating horizontal sweep is necessary for a continuously operating SCR regulator. But good SCR operation is necessary for normal horizontal sweep. This nuzzle can be solved during troubleshooting sometimes by eliminating the SCR regulator circuit and reducing the input line voltage to compensate. Add two jumper test leads as shown durüng these tests. Remove them later. August 1986 Electronic Servicing & Technologe 13 0402 Q401 AFC OSC SWITCH Q403 HORIZ INVERTe 0411 HORIZ DRIVER +19.5V +9.2V tie +10.5V Q404 TRIGGER +10.7V t +20V RCA horizontal REPLACE [PARTIAL SCHEMATIC] +20V OSC Figure 3. As shown by this partial schematic, Q402 oscillator switch and 0403 horizontal inverter are two transistors in the horizontal oscillator circuit. They have caused some problems in the past and required replacement. (K) is normal. A reading above 1M(] should be measured between anode (A) and cathode (K). Replace any SCR that has an open gate reading or a low anode-to -cathode reading. While SCR101 is removed, clip test leads between the SCR101 socket from cathode to gate and cathode to + 164V supply (Figure 2). Disregard the voltages shown in Figure 2, they are for normal operation. Obviously, all three terminals of SCR101 should have the same voltage. Plug the ac -power plug into a variable -voltage transformer. Begin at a very low voltage, say 30Vac, and slowly increase the receiver's ac input voltage until approximately + 80V to + 85V is measured at the horizontal-output transistor's collector. It is a good sign when a picture or raster appears, for it indicates the horizontal -sweep system is operating (at least under those special conditions). If smoke or any other symptom of overload appears (such as the low -voltage do voltage not increasing in step with the increasing ac input), switch off the TV and do more power -off testing; the job is not finished, although the SCR has had a negative test and probably is not at fault. Determine if the horizontal circuits are normal by scoping the base of the Q412 horizontal -output transistor. A lack of signal there indicates problems in the horizontal -driver stage or in the oscillator system. If the base signal has sufficient amplitude with a normal waveform, check the Q412 14 Electronic Servicing & Technology collector waveform. A well -shaped single, strong pulse for each cycle indicates all is well. But a weak pulse with a weaker pulse between each pair of correctly placed pulses indicates an excessive load on the flyback. Singing flybacks A flyback can sing only when supplied with frequencies much lower than the normal 15,734Hz operating signal. This lower frequency might be there instead of the correct 15,734Hz signal, or it might be mixed with it. The defect might or might not allow something to be seen on the CRT screen. There are many possible causes for a singing flyback, so some general tips will be given. Arcs seldom are steady enough to cause a singing sound. Also, arcs usually have a distinctive sound that identifies them immediately to technicians who have heard several kinds of arcs. Some singing flybacks are caused by parasitic oscillations in the horizontal -sweep circuit produced by open B + filter capacitors, open decoupling capacitors or defects in the horizontal circuitry, especially the oscillator stage. For the first test, scope the base waveform of Q412 horizontal - output transistor. A distorted waveform (or a good waveform with a smaller waveshape traveling across the main waveform) indicates the problem is upstream from Q412. Scope the input and output waveform of Q411, the horizontal -driver transistor, while noticing such common symptoms August 1986 as incorrect do voltages at base and collector or Q411 operating too warm. If the Q411 waveform is no better than the one at Q412's base, go back to the horizontal oscillator circuit, particularly the Q402 oscillator switch transistor and the Q403 oscillator horizontal inverter. Test these two transistors carefully for junction conduction voltage drops and for reverse leakage. If there is any doubt about their condition, replace them (Figure 3); they have a history of failures. Use original RCA transistors or GE-20 for Q402 and GE82 for Q403. If the singing flyback is not quieted, concentrate on the Q412 output stage. If the screen is blank and without a raster, measure the high voltage. Also, scope the Q412 collector, checking for correct waveform, amplitude and frequency. Those of you having a scope with an internal frequency counter are fortunate. Others can obtain an approximate frequency by noticing where the scope's frequency -sweep or sweep-time controls must be adjusted to obtain a single cycle of reasonable stability. A frequency of perhaps 8kHz can make a flyback sing, but the high voltage and deflection probably will be very low. The most likely cause of flyback singing has been held until the end: insufficient drive to the Q412 horizontal -output base. Verify this by scoping the base. Check for shorted turns in the T401 driver transformer windings. Serious shorts can affect the coil's resistance readings. Also, visually SHORTED OR LEAKY HOR Z OUTPUT 1 CR405 LEAKY C417 [119V] T402 [22.5KV] +119V FLYBACK 22-23.5KV HV TO CRT ANODE C434 .0058T 390pF /4 CHECK: C417 C434 CR405 0412 RCA horizontal output B A TO YOKE Q412 ±- +120V REGULATED Figure 4. The horizontal -output stage in RCA CTC107 color receivers is not different in general from many other brands and models. However, many details are different. Arrows point to components most likely to cause overloads or excessive high voltage. Notice the flyback is the integrated type having HV diodes Inside the HV windings. IL. examine all four soldered joints at T401. Resolder them carefully if there is the slightest doubt about their conditions. Accurately test R428 (5,6002), R429 (12), C414 (0.1µF) and other resistors in the Q412 base circuit. If no defects are found around T401 and the Q412 base, work upstream to the horizontal -driver transistor, and then to the horizontal-oscillator transis- tors, as discussed before. Some of these tests are almost certain to find the defect causing the singing flyback. Chassis in tick -tick mode A faint tick -tick -tick sound from the flyback is evidence that the SCR-regulator circuit is attempting to regulate the + 120V to the horizontal -sweep system that is not operating. Without horizontal, the regulator cannot operate correctly, and the very -low frequency sawtooth that results sounds like a tick. We have found several leaky CR407 diodes (in the + 45V power supply) that produced the tick -tick (and stopped the TV operation). Another cause of tick -tick without picture has been defective Lowest Prices Off -The -Shelf Directly To You TEST INSTRUMENTS HITACHI 35 MHz DUAL TRACE OSCILLOSCOPE B&K FORDHAM 60 MHz TRIPLE TRACE OSCILLOSCOPE SWEEP FUNCTION GENERATOR Model V-355 Model FG -801 $59995 (Reg. $899.95) Probes included. Model 1560 $19995 $89995 (Reg. $289.95) Test Leads included. rectangular, internal graticule CRT Autofocus LOGIC PROBE FREÌ j5eCiAG (Reg. $1150) Probes included. Thin, lightweight, compact Large 6" BP LP189 ($40.00 VALUE) with purchase of Model V-355 FORDHAM 550 MHz FREQUENCY COUNTER 1 mV/div sensitivity frequency ranges, 0.2 Hz to 2 MHz Accuracy to ±5% 7 22 calibrated sweeps Rectangular CRT w/internal graticule & scale illumination Autofocus FLUKE & 31/2 VOLTMETERS HITACHI DIGIT MULTIMETERS $1249" Model FM -8 (Reg. $1980) Probes included. Large 6" rectangular CRT w/intemal graticule Delayed alternate and Model 73 $169'5 (Reg. $249.95) Model 75 Completely assembled, pre -tested, pre calibrated High intensity 8 -digit LED display Model 77-F 100 MHz QUAD TRACE DELAYED SWEEP OSCILLOSCOPE Model V -1050F Q45 $8995 single sweep functions Autofocus $11995 Service M=1"81 ilgATAI.067 Phone orders accepted. Fordham 800-645-9518 FREE Toll 260 Motor Parkway, Hauppauge, NY 11788 Free In NY State 800-832-1446 Circle & Shipping Charge Schedule Continental U.S.A. FOR ORDERS $25-100 $101-250 $251-500 $501-750 $751-1,000 $1,001-1500 $1,501-2000 $2,001 and Up ADD $4.50 $6.00 $8.00 $10.50 $12.50 $16.50 $20.00 $25.00 (8) on Reply Card August 1986 Electronic Servicing & Technology 15 R813 1000 R811 C815 T 100pF R812 Ç 360 470' C81 4 C818 5-2PF /7 L805 Cß13 Y8011 3. SBMHz R808 150pFT 3300> 2 +5V +5V 11 GREEN DRIVE +7.6V 2VPP 5 CHROMA +9.2V +3.6V PART 7VPP HORIZ PULSES 5 U701 OF +6.4V " +7.2V ERRATIC COLOR R817 330K 1F C808 01I +10.5V BLUE DRIVE +3.3V+3.4'1 C806 . o +3.3V 22 R803 3.3M> RED DRIVE C809 .01= R X03 COLOR 100K Color problems OPEN Figure 6. Arrows point to components around U701 that have caused color problems in the RCA CTC107. damage can occur from excessive high voltage. Therefore, the variable ac -voltage transformer must be connected to the chassis ac cable. Monitor the + 120V source (or the Q412 collector) and the HV at the picture tube as you slowly increase the line voltage. If shutdown occurs with only about + 90V at Q412 but the high voltage before shutdown was more than 24.5kV, the suspect is the Q412 and the flyback/yoke system. C417 (0.0058µF) is the prime suspect; an open capacitance tunes the output circuit to a higher frequency thus producing narrower and higher amplitude pulses at the Q412 collector. An intermittent SCR101 can produce a picture, give an erratic squeal and then cause shutdown. However, those are not the symptoms we described. If a variable -voltage transformer is not available, the procedure is different. C417 should be tested and replaced if open or suspected. Temporarily disconnect the X-ray safety shutdown circuit (Figure 5) by unsoldering the Q414 emitter wiring where it is sent to the Q411 horizontal -driver transistor's base. Arrange for monitoring of the horizontal -output transistor's collector dc voltage and the high voltage (using a HV probe). When the meters are connected securely, plug the ac power and switch it on. Read the meters as soon as possi18 Electronic Servicing & Technology ble, write down the readings and then turn off the receiver power. Analyze the two voltages. If the Q412 collector reading is + 119V to + 120V, that is normal. If the high voltage is between 22kV and 23kV, there is no problem with the sweep output. Therefore, it is safe to reconnect the Q414 emitter wiring to the Q411 base wiring, as re- quired to protect the receiver. However, if the high voltage tests 25kV or higher, this must be repaired before Q414 can be connected, otherwise shutdown will result. For curious technicians, the latch works like this: Q414 and Q413 form a regenerative latch with the base of one connected to the collector of the other. When not activated, one transistor has about zero bias while the other has reverse bias, so no operation is possible. When the flyback pulses exceed a certain level, the Q413 emitter becomes more positive than its base. This is forward bias for the PNP and Q413 conducts some of the positive emitter voltage through the E/C path to the base of Q414. Of course, this positive base voltage is forward bias for the NPN and Q414 draws current and amplifies. As the Q414 collector voltage decreases so does the Q413 base; Q413 draws more current causing its collector to become more positive. The collector is tied to the Q414 base so this August 1986 increases the forward bias. Almost instantly, both transistors become completely saturated with maximum current, and a fairly high positive voltage at the Q414 emitter. This voltage is sent to the base of Q411, the horizontal -driver transistor, where the excessive forward bias produces saturation driver current for a fraction of a second. During that time, the saturation current reduces the driver gain to zero, so the horizontal sweep stops. That's all, except for the Q415 section that indirectly measures the CRT current (by monitoring the voltage from the cold end of the HV winding). Normal bias for Q415 through R452 ande R451 (reduced by R450) is saturation bias. Going back a step, the rectified voltage from flyback pulses is divided by two precision resistors (R434 and R436). But R436 is grounded through Q415 for safety operation against excessive flyback and HV voltages. Q413 is easier to trigger if R436 is increased in value, which is the operation of the overcurrent shutdown. When the CRT draws excessive current through the flyback, the pin -2 voltage becomes less positive than before. This less positive voltage comes through R450 to the Q415 base where most of the saturation bias is cancelled. Q415's collector resistance and voltage rises, and with it the Q413 LEAKY CR1114 -.. C115 330µF R341 originate in the low -voltage power supply (Figure 7). The most likely failure is zener diode CR302. If not CR302, then check CR706 with the DMM's diode test, and check C709 (47µF) and C327 (220µF) with a capacitance meter. One is almost certain to be defective. If the proper 3.58MHz sinewave waveform is not scoped at pin 13 of U701, replace Y801, the color oscillator crystal. The color padder C818 also has been known to kill the color. Other color problems were caused by bad soldered connections at R803 and C806. Make certain the 7VPP horizontal pulses are at pin 7. Replace U701 IC if all these tests have been negative. SOURCE 112,- 680 R324 1600 +26.1V +21.8V SOURCE R329 160 18.3V C336 22µFLIJ 2W +11.24V SOURCE C327 LEAKY +11.9V CR302 12V 220µF` +10.53V SOURCE CR706 C709 LOW 47µF`=' VOLTAGE LEAKY Power supply stops the color Figure 7. Although the schematic shows many components that can possibly affect the power-supply voltages, the one most often affecting the + 11.24V and + 10.53V supplies is zener diode CR302. Place it at the top of our testing list. emitter voltage, initiating shutdown. After all repairs have been made, and you believe all circuits (including the shutdown) are operating correctly, test the shutdown operation by connecting together testpoints XT1 and XT2. Immediately the receiver should go into shutdown. If it does not, the shutdown circuit must be repaired. These testpoints are supplied for this purpose and are very helpful. They are located in front of the flyback. Other horizontal problems Arc -type noise lines in the raster might be caused by a defective integrated -diodes high -voltage transformer. Bands of noise at the top of a picture can be produced by a defective horizontal -drive Q411 transistor. For a case of horizontal jitters, check capacitor C410. An open C417 and or C117 can cause narrow width with excessive high voltage. Arcing that cannot be seen or located might be in the yoke, but making lines in the picture. Color problems In the RCA CTC107, color originates in the luminance/ chroma U701 IC. The color signals are best checked with a scope at IC terminals 3, 7, 13, 15, 20, 21 and 22. A carrier of the 3.58MHz chroma oscillator should appear at pin 13. Horizontal pulses (sandcastle waveform) enter at pin 7. Three demodulated output color signals exit from pins 20, 21 and 22. If any of these are missing, you must find out if the IC or other circuitry is responsible, and the missing signal must be restored before you proceed (Figure 6). Many problems are caused by U701 itself. These include no color, very weak color, incorrect tint, lack of color sync or a missing output color. After scoping all the points mentioned previously, take accurate do voltage measurements at pins 23, 2, 20, 21, 22 and 27. If the + 10.5 voltage source at pin 23 is low, suspect a leaky IC or a power supply problem. Check the IC by removing pin 23 from the circuit using solder wick and soldering iron. If the + 10.5V source returns to normal or increases significantly, U701 is leaky and should be replaced. No color Scope the various color terminals on U701 when there is no color. Accurately measure all IC do voltages. A low reading or zero at the + 10.5V source is likely to Weak color Rotate the R4203 color control completely clockwise and adjust the tint control to the center of rotation when the color is weak. Test Q801 in -circuit. Rotate R805 the chroma peak -level control for maximum color (it must be reduced later). Check L805 for an open circuit. One of these should have found the original problem. If not, replace U701. Readjust R805. Intermittent color Color crystal Y801 and trimmer capacitor C818 have caused many intermittent color symptoms. Replace them, and then adjust C818, because C818 can cause color stripes when it is misadjusted. Also, intermittent color can be caused by a defective 1µF C806 (Figure 6). IC U701 is often responsible for erratic color. When it has color, spray U701 several times with canned coolant to determine if the color is affected. An intermittent + 10.53V power source can cause intermittent color. Check for bad soldered connections around the Q302 12V regulator. If the supply continues to be intermittent, replace Q302. When one color is missing from the color and from the raster, scope U701 pins 20, 21 and 22. Replace U701 if the video waveform is weak or missing at any of these terminals. However, if all three signals are good at U701, go to the color - August 1986 Electronic Servicing & Technology 19 01 RED DRIVER R735 120 FROM R4 2200 TO RED CRT CATHODE Q704 R N CHANGED 10K R749 1500 age at the amplifier and the CRT cathode increases the brightness of that color. That is true of all three colors. According to the previous analysis, the example given in the schematic should have been extremely bright red with very little green and blue. It was not one color missing, but one increased and two decreased as the brightness was turned down. VALUE OPEN RB 27K L1 R 4500 RED BIAS +10.53V +193V,s__--LOW BOOST One color missing from raster Figure 8. Problems in the three power transistors that apply complete red, green and blue color signals to the separate picture -tube cathodes can change the raster and picture color drastically. Some defects can brighten one color and dim the other two. Another problem can dim one color and brighten the other two. If the specific problem is an open L1, the Q1 collector voltage would be reduced, and with it the red cathode. Therefore, the red color would become much brighter. T402 R125 +193V BOOST SOURCE 4.7 FLYBACK CR112 9 noise. Using small wood wedges or toothpicks, try to place them between the winding and the metal core. If this stops the squeals, glue the pieces of wood into place, and C117 30µFY 60VPP NEGATIVE PULSES TO TUNER OPEN Tuner problem Figure 9. An open circuit in L103 removes the 60VPP from terminal 5 on the tuner control unit so the tuner cannot receive any channels. Some of these opens are bad joints at the ends of L103. Resolder or replace the coil as required. driver transistors (Figure 8). Don't neglect the other two entirely, but concentrate on the one for the missing color. Accurately measure the base, emitter and collector voltages. In this example, the Q1 collector voltage was low. There are basically three possibilities for a low collector voltage; the transistor is drawing excessive current; the collector resistor has increased in value; the L1 peaking coil is open and its 27k damping resistance (R8) has been added to the 10k collector load. L1 was open, as proved by the simple temporary expedient of shorting across L1. All three colors appeared on the screen. Perhaps we should review at this time what happens with various combinations of CRT cathode volt20 Electronic Servicing & Technology Unusual problems Intermittent horizontal squeals from the CTC107C flyback transformer sometimes are caused by loose particles inside the flyback. Sometimes, pushing against the plastic part of the transformer with an insulated tool will stop the noise for a time. Notice if the CRT filament winding or the high voltage section is making the ages. Of course, you know that each of the three cathodes has a complete color signal fed to it along with a do voltage. This do voltage is the major factor for CRT brightness levels and for obtaining the correct gray scale tracking that is the correct base for the color picture. The next important point is that each color-amplifier collector is direct -connected to its corresponding picture -tube cathode. That means the CRT cathode voltage change vs. brightness change is reversed compared to connecting the color signals to individual CRT grids. Remember these facts: increasing the positive voltage at an amplifier and a CRT cathode decreases the brightness of that color. Decreasing the positive volt- August 1986 tighten the outside metal support strip. Replace the flyback, if the squealing noise continues and cannot be stopped. When the channel numbers and tuner control cannot tune in any stations, suspect a missing 60VPP horizontal -frequency series of pulses from the flyback circuit (Figure 9). Because the signal is made up of ac pulses, á DMM cannot read the voltage. Instead, scope terminal 5 on the tuner control module. If the pulses are missing, verify the diagnosis by switching off the power and testing the resistance from terminal 5 to ground; it should be a low reading but an open circuit will change it to a very high reading. Bad soldering of poorly tinned terminals on L103 might produce the open circuit. Repair by carefully soldering the L103 joints and then testing from tuner-control terminal 5 to ground to verify the continuity before power is applied. When the 60VPP pulses are restored to terminal 5 of the tuner control unit, the tuner system should tune all channels properly. time than it took you to read just the As soon as the set shuts down, or otherwise fails, the Mark VII will "Zero In" on why it first ten words of this sentence - - failed, lite and latch the proper indicator problem, in You could have diagnosed any light, automatically turn itself and the TV any brand, solid state TV set down to circuit set off, then, sit there idle (with one light lit) level, with 100% accuracy. awaiting your return. In less By simply plugging the set's AC cord into a self programming Mark VII computer, pushing one test button, and noticing which one of sixty lights are lit. The light that is lit tells you which circuit or stage is not functional. All this by just plugging in the AC cord. No other connections are required. (In certain cases of low end, LV regulator shut down, you may have to bridge the LV regulator with an LV rect. other than this occasional inconvenience, no other connections are required. An adapter plug is provided for such instances.) With a Mark VII you could accurately diagnose 400 TV sets down to circuit level In nine out of ten instances, you can do so won't without even removing the back of the TV in one 8 hour day. Unfortunately, you be able to replace the defective parts that set! (Talk about fast estimates) quickly! - INTERMITTENTS - NO PROBLEM WHATEVER DIEHL ! Leave the TV set's AC cord plugged into your Mark VII, leave the computer turned on, and go home for the weekend! Call (806) 359-0329 for more info 6661 Canyon Dr. Circle (10) on Reply Card August 1986 Amarillo, TX 79110 Electronic Servicing & Technology 21 Maintenance and lubrication By Conrad Persson Today's electronic and electromechanical products: televisions, stereos, compact digital audio disk players (CDs), printers, need remarkably little care and maintenance. They chug along day in and day out without complaint, bringing the world into your living room, surrounding you with beautiful music, or keeping track of your checkbook. Unfortunately, this reliability lulls a lot of people into a false sense of security and their electronic genies deteriorate, so slowly that their performance falls off gradually. They are no longer near peak output, but the owner does not know it. Or, all of a sudden, one day they just cease to operate. Preventive maintenance A little preventive maintenance: cleaning, lubrication, alignment of mechanical parts, can go a long way toward keeping today's con- sumer electronics products operating at peak performance. Unfortunately a lot of people feel that if a little is good, a lot is better, and tend to get carried away. With preventive maintenance, a little, as recommended by the manufacturer, goes a very long way. Excessive cleaning of some components can cause excessive wear. Too much lubrication (or the wrong kind) can get onto drive components and cause slippage, or can gum up the works and cause sluggish operation. 22 Electronic Servicing & Technology Dust and dirt may be blown out of hard -to -reach places by using any of a number of products that consist of some kind of gas under pressure. The Dust -Off System contains, according to the manufacturer, triple filtered, purified air. (Photo courtesy Falcon Safety Products.) August 1986 Circle (135) on Reply Card ADVERTISEMENT NOTICE company is confronted with troubleshooting or otherwise repairing a certain type, or piece of equipment on a frequent basis If your i.e. TV sets, VCR's, Electronic Cameras, Copy Machines, Amplifiers, Industrial Controls, Answering Machines, Radios, Robotics, Bio Medical, Military, Avionics, etc., etc., etc., - - The odds are staggering that we could custom program one of our Mark VII computers to accurately isolate any failure in any such device (down to circuit level) in less than two seconds! INTERMITTANTS POSE NO PROBLEM (See our display ad on page 21) DIEHL 6661 Canyon Drive Amarillo, TX 79110 ADVERTISEMENT August 1986 Electronic Servicing & Technology 23 The effects of dirt One of the worst enemies of electronics equipment is dust and dirt. Video screens attract dust because of the static electricity they High -voltage components also attract dust. Another cause of dust buildup in electronics products is natural or forced convection through heat generating parts. Manufacturers have openings in the top of equipment to let out the air heated by the electronic components, and holes in the bottom back or sides to let in cool air. This can tend to result in a buildup of dust that cuts down on the desired convection and leads to overheating and subsequent early failure of components. Another problem with dirt occurs when audio or video, or computer disk drive heads get clogged with the oxides from the tape or disk. The most obvious of these problems is in VCRs. When video heads become clogged the symptom is absence of picture information and a so-called dropout on the screen. When audio heads become clogged the symptom may be anything from a vague loss of fidelity to drastically deteriorated sound quality. In the case of clogging of disk drive heads, the absence of a bit or two that wasn't read might be so subtle as to be undetectable except under very unusual circumstances, or it might generate. 24 Electronic Servicing & Technology Kits such as this contatln all products needed to keep a personal computer clean and operating properly: lint -free swabs and wipes, pressurized air cleaner, anti -static spray and more. (Photo courtesy Philips ECG) Circle (136) on Reply Card. August 1986 ADVERTISEMENT WARRANTY WORK When you compare time spent to pay received, you might find it difficult to survive on some of the warranty allowances in today's market. If so, this ad will serve as a reminder - - - time than it takes you to print the customer's name on a warranty tag, a Mark VII computer will diagnose the failure down to circuit level. In most cases it will do so - - - without even removing the back! In less If your local factory field service representative says it can't be done, remind him that Diehl will pay any engineer / technician a year's wages who can troubleshoot just three of his most familiar TV sets, before a Mark VII can troubleshoot thirty!! Hopefully, this challenge will either cause him to take his foot out of his mouth, - - - or finish putting it in! -INTERMITTENTS POSE NO PROBLEMS(See our display ad on page 21) DIEHL Call (806) 359-0329 for 6661 Canyon Drive more info. Amarillo, TX 79110 ADVERTISEMENT August 1986 Electronic Servicing & Technology 25 be so severe as to render the drive virtually unusable. Computer keyboards are another type of equipment that can cause problems when the key switches get dirty. The problem may be anything from a simple intermittent letter that refuses to communicate the desired information to the computer, to a fullfledged refusal to operate. The controversy about head cleaning tapes There is a controversy concerning the use of head -cleaning tape are somewhat abrasive, especially the dry cleaning tapes, and excessive use can cause premature wear of the heads. systems for VCRs. The manufac- turers of such systems, not sur- prisingly, recommend their Vacuum cleaners and blow -off systems The dust that accumulates in consumer electronic products can cause problems in a variety of ways. As mentioned earlier, it can interfere with ventilation causing heat buildup. It can create extraneous current paths, resulting in impaired operation. On a computer, dust can infiltrate into the keyswitches of the keyboard and cause intermittent key input problems. In the printer, airborne dust and paper dust can interfere with print mechanisms, cause poor regular use. VCR manufacturers, on the other hand, do not wholeheartedly recommend their regular use. For example, the Panasonic VCR owner's manual discourages regular use of VCR Keeping it clean head cleaning tapes, stating that if It really isn't difficult to correct the picture looks good, don't VCR the effects of dust and dirt. In fact, in many cases it's possible through use any kind of head cleaning the use of dust covers to reduce system: in essence, "if it ain't dirt accumulation in the first place. broke, don't fix it." At least part of the reason for When the equipment does need discouraging regular use of head to be spruced up, and some of the accumulations may not be ap- cleaning tapes is that most of them parent without an occasional inspection, there are a number of ways and products to take care of the problem. For example, in the case of the TV or monitor screen, usually it's pretty obvious when dust has accumulated there. In extreme Luge" Super cases, the dust interferes with Super Lube" Multi -Purpose Multi -Purpose viewing. Simply dusting the screen Lubricant with Teflon' Lubricant with Teflon .xw.nn«.urs.don u.oand .,.,n.. u.N ..and will remove the dust. The static o.. o -n electricity generated, however. Ittentear,a.. may accelerate the return of dust. To combat this problem, a number of manufacturers have come up with products that remove static M-N...N....N. ,Wp frt. .... See., Met. electricity as they clean and hence nnp{Gud.......¿' roMev.mu..fr inhibit dust buildup. : .m w -... s,.-,..pp..N.. For the head clog problem, there seem to be any number of products of l# and approaches to cleaning the 7.38 heads. The best method for VCRs, recommended by most manufacturers and the Electronic Industries Association/Consumer Electronics Group, is shown in the accompanying diagram. Wet a foam stick (specially made for this purpose) with the recommended amount of the recommended solvent, and rub the head in the horizontal direction only. Audio and disk drive heads may n.a.mon onanPa Rug.flärer end Coo.,on That Cep .111 deum ca.. Olee dipplabefw »free fete :$'^n.Y.. ,. M,.... PEEP OUT -`v- OF CHILL/II! .25 FL OZ be similarly cleaned with lint -free swabs recommended by the manufacturer, and the appropriate solvent. 26 Electronic Servicing This lubricant, called Super Lube, is a multipurpose lubricant formulated from Teflon and a synthetic grease. According to the manufacturer, it is non -corrosive and nonpolluting, making it suitable for use in the maintenance and repair of electronic office equipment, including computer printers, typewriters and calculators. (Photo courtesy Falcon Safety Products.) & Technology ml August 1986 Circle (137) on Reply Card ULTI ,; ETERS AWS DM -7010 41/2 DIGIT ROTARY SWITCH DMM High accuracy readings in the laboratory or in the field. Features include 41/2 digit 19999 max. display; built-in frequency counter to 200KHz and conductance function; 0.05% basic dc volts accuracy; DM -3000 3'/2 DIGIT ROTARY SWITCH DMM Just one of :hree DMM's in our Economy Series that ;omDines quality with economy. Features include built-in HFE, battery and diode testing; conductance function; 3C0 hour battery life; 10Adc range; electronic overload protection on all resistance ranges; pocket -sized. (Also available models 0M-1000 & 2000). Ranges: 0-200m/2/20/200/ 1000Vdc; overload protection on all ranges; special electronic protection to 250Vac/dc on resistance ranges; UL1244 type test leads; diode and continuity tests. Ranges: 0-200m/2/20/200/ 1000Vdc; 0-200m/2/20/200/750Vac; 0-200p/ 2m/20m/2JOm/10Aac/dc; 0.200/2K/ 20K/200K/2Mi20M 9 1.5V battery 0-200m/2/20/200/750Vac; 0-200p/ 2m/20m/200m/2/10Aac/dc; 0-200/ 2K/20K/200K/2M/20M Ç? 0-200nS ; test 0-100C Hfe test; 2K 9 diode test. DM -1000: $39.95 / DM -2000: $54.95 / DM -3000: $69.95. ; conductance; 0-20K/200KHz frequency. $170.00. DM -8010 31/2 DIGIT ROTARY SWITCH DMM EZ -6111 31h DIGIT AUTORANGING DMM Unique and sopiisticated in design, you'll find measurement taking a breeze. Loaded with fea ores like autoranging in volts and ohms; manual range selection in all functions; diode test function; audible continuiy indication; normal and low power ohm ranges; 10Aac/dc range; overload prctection on all ranges; 300 hour battery life. Ranges: 0-200m/2/ 20/200/1000Vdc; 0-2/20/200/ 600Vac; 0-20m/200m/10Aac/dc; 0-200/2K/20K/200K/2ML? 0-2K/ 20K/200K/?MS? Lo9 $99.95. ; .01 This easy to use DMM features a dc Volt accuracy of 0.25% of reading; overload protection on all ranges; special electronic protection to 500Vac/dc on re- sistance ranges; instant audible continuity buzzer; UL1244 type test leads; auto zero and auto polarity; diode test function; built-in tilt stand. Ranges: 0-200m/2/ 20/200/1000Vdc; 0-200m/2/20/200/ 750Vac; 0.20p/200p/2m/20m/200m/ 10Aac/dc; 0-20/200/2K/20K/200K/ 2M/20M4 $84.95. . . DM -3010 31/2 DIGIT PUSH BUTTON DMM The standard in tough, job -proven digital ..-: tur .. 4 ., 4' P» DM -6592 ELECTRO-PROBETM DMM One of the smallest, most convenient hand-held DMM's you'll ever own. It's multimeters. Housed in shock resistant ABS plastic, you'll find safety was a prime design consideration. Also equipped with overload prctection on all ranges; special electronic protection to 500Vac/dc on resistance ranges; UL1244 type test leads; normal and low power ohm ranges; 10Aac/dc ange auto zero and auto polarity; built-in tilt stand. Ranges: 0- both autoranging and manual and is the 200m/2/20/200/1000Vdc; 0-200m/ 2/20/200/750Vac; 0-200p/2m/20m/ 200m/2/10Aac/dc; 0-200/2K/20K/ 2000K/20M 200K/2M/20MS? . perfect instrument for taking readings easily and accurately in hard to reach areas. Other features include instant audible continuity buzzer; one -hand operation; electronic overload protection on all ranges; data -hold button. Ranges: 0- 200m/2/20/200/500Vdc; 0-2/20/ 200/500Vac; 0-200/2K/20K/200K/ S2. $65.00. $80.00. DM -6500 3' DIGIT AUTORANGING OMM This sensitive yet rugged instrument is loaded with features you'd expect to pay much more for. The 6500 offers auto ranging; low battery consumption; fuse protection; safety test leads; audible continuity buzzer; auto zeroing; shock resistant housing. Ranges: 0-200m/2/20/ 200/1000Vdc; C-2/20/200/600Vac; 0-200m/10Aac/dc; 0-200/2K/20K/ 200K/2M9. $80.00. DM -1 POCKET-PROTM DMM Big features are packed in this pocket calculator sized DMM. You'll find auto ranging; electronic overload protection on all ranges; auto -polarity; audible and visual continuity indication; built-in test leads; "booklet -type" carrying case is de- signed to fit easily in shirt pocket Ranges: 0-2000m/20/200/400Vac/dc; 0-200/2000/20K/200K/2000K 9 0-200 S? continuity. $29.95. A.W. SPERRY INSTRUMENTS INC. For more information see your local distributor or contact A.W. Sperry Instruments Inc. 800-645-5398 Toll -Free (N.Y. and Alaska call collect 516-231-7050). 245 Marcus Blvd., Hauppauge, N.Y. 11788 Circle (11) on Reply Card ; Procedure for cleaning upper cylinder unit Head cleaning sticks, as shown, are recommended both by VCR manufacturers and by the Electronic Industries Association/Consumer Products Group. Using them as described will "provide adequate results with the least possible chance of damage to the video heads." (Electronic Servicing & Technology, January 1986.) UPPER CYLINDER This article also advises that only manufacturer -recommended materials be used for any VCR maintenance, and that, when a video head needs replacing, the entire upper head cylinder be replaced, instead. Position the video head to permit access for cleaning and hold the upper cylinder to keep it from turning while cleaning. 2. Gently rub the video head in direction of tape travel with head cleaning stick (CFK27) moistened with Freon TF. 3. Repeat for the other video head 1. Note: 1. Do not rub vertically. not apply any pressure to head. If contaminant is not easily removed, continued gentle wiping will usually remove the contaminant. 2. Do VIDEO HEAD CLEANING STICK quality printing and sluggish operation. Regularly cleaning dust and dirt out of consumer electronics equipment will eliminate these problems. A standard vacuum cleaner with crevice tool and upholstery brush attachments will remove a lot of these dusty problems. Unfortunately, compared to the dimensions of many of today's consumer electronics products, a standard vacuum cleaner is very puter system, including a disk what we have turned up so far. drive and a printer. Strangely On the subject of VCR's, Howard enough, the manufacturers' W. Sams Photofact folders recomavailable servicing literature mend that bushings and bearings seems to be silent on the subject of be lightly lubricated with machine lubrication. oil and cam surfaces be lightly At this moment, we're still lubricated with a non-drying researching the subject of lubrica- grease. Please note the word tion of mechanisms, but here's "lightly." Keep in mind that any large. For these situations, specially manufactured miniature vacuum cleaners can get into those hard to reach places. For still other situations, gas under pressure may be used to blow dust and dirt away. A number of manufacturers offer cans of air under pressure or similar products with spray nozzles to be used for this purpose. Lubrication For years, the only consumer electronics products that might need lubrication were the turntable and the tape recorder. That has changed dramatically. A wellequipped home entertainment center of today might boast not only the audiotape recorder and turntable or changer, but a VCR and a CD player, as well. In the office at home, there might be a com28 Electronic Servicing & Technology These head -cleaning sticks, according to the manufacturer, have tips of ultra cleaned natural chamois leather for cleaning and polishing video/audio heads safely and effectively. (Photo courtesy Chemtronics.) Circle (138) on Reply Card August 1986 e lubricant that is not doing a job of providing slipperiness between two surfaces that need it is nothing more than another contaminant. A search of literature on maintenance of electromechanical devices related to computers also turned up a great silence on the subject of lubrication. One source, "The 1541 Repair and Maintenance Handbook" (the 1541 is the disk drive manufactured by Commodore for use with the Commodore 64), by Rienhold Herrmann, published by Abacus Software, Grand Rapids, MI, discusses lubrication (in addition to a thorough treatise on just about every aspect of repair and maintenance of these units). This guide recommends applying a thin film of acid-free grease (Vaseline, for example) to the read/write head carrier guide rails and application of a drop of sewing machine oil (one drop, not two) to such points as the disk drive axle, the disk ejection lever and the lock wheel, washer and shaft. WP -707 Dual DC power supply, 0-25V 0-2A Automatic Short Circuit Shutdown with Reset Button. Excellent Line & Load Regulation. Uncommon sense It would seem that cleaning, maintenance and lubrication of electromechanical components of electronic systems would be dictated by common sense: if two parts run or slide on one another, lubricate them. This is apparently not always the case. My Star SG-10 printer, for example, has a dot-matrix print head that is driven along a smooth, cylindrical shaft. Nowhere in the thick, exhaustive operation manual does it say anything about lubricating the shaft. I have no plans to put anything on it until I learn otherwise, or until it somehow shows evidence of needing it. When it comes to routine cleaning, lubrication and maintenance of electromechanical portions of electronic systems, uncommon sense suggests that you check with the manufacturer, if possible, before you take a chance on gumming things up. 115f1U, indicators. digital voltmeters with range of LED overload Two 0 to 99.9 VDC. May be used to measure DC source voltage or current. May be used in series to provide 0-50V DC (ci 0-2A WP-712A Single output 20V, 2A with excellent line and load regulation. VIZ's line of DC power supplies have a contemporary new design along with up-to-date features and specifications which offer you laboratory and industrial type performance-with style. This line of DC WP-105A 0-50V, 2A regulated output, DC voltmeter, continuously variable between ranges. power supplies is well suited for servicing a wide variety of electronic equipment as well as production testing, circuit design, quality inspection and educational applications. Single, Dual & Triple output units are available. The WP-707A dual power supply has two digital panel meters which can be switched to monitor voltage and, or current of either , tput. an division o 335 E PRICE STREET, PHILADELPHIA, PA 19144 215/844-2626 TLX 710-670-2626 800,523-3696 .c rng Co Circle (12) on Reply Card August 1986 Electronic Servicing & Technology 29 Test your electronic knowledge By Sam Wilson I have heard many technicians comment that the Second Class FCC license test was the most difficult of all FCC tests. It was a test that covered a wide variety of subjects. The other tests were more specialized. Because this test covers a wide variety of subjects, you will probably find it difficult. A score of 50% is good for a test like this. 1. You have a transformer designed for use on a 400Hz, 115V power line. If you connect this transformer to a 60Hz, 115V power line, A.) the transformer laminations will vibrate. B.) the transformer will run hotter. C.) the transformer will run cooler. D.) the transformer will operate very efficiently. E.) (none of these choices is correct). 2. You cannot improve the image rejection of a receiver by A.) increasing the IF. B.) phase locking the local oscillator. C.) using a pre -amplifier. D.) using high -Q circuits in the RF amplifier. E.) (all of these choices are correct). 3. Eutectic solder A.) does not require heat. B.) has a bismuth core. C.) goes directly from a solid state to a liquid state when heated. D.) is used for connecting plastics. E ) does not actually exist. cessive high -frequency response. Which of the waveforms in Figure 1 would you expect to scope at the output? A.) the one marked A B.) the one marked B C.) the one marked C D.) the one marked D E.) (none of these choices is correct.) 5. Which of the output waveforms in Figure 2 is correct for the circuit and input waveform? 6. Connect the coils and battery circuit in Figure 3 to obtain maximum flux in the iron core. 7. Everyone knows that the Wheatstone Bridge is used for measuring resistance. When modified, it can also be used to follows: A.) Both are used to measure capacitance. B.) The Hay Bridge is used to measure capacitance and the Maxwell Bridge is used to measure inductance. = 400Hz. B.) horizontal = 400Hz, vertical = 300Hz. C.) Neither choice can be correct. The Z-axis of an oscilloscope: A.) is used for making Lissajous 9. patterns. B.) is used for blanking the trace. C.) permits it to be used for mak- ing 3 -dimensional computer drawings. D.) is another name for the sweep (or trace). 10. To check the on -off switch of an electronic circuit, a milliammeter is connected across the switch. The meter should read OmA when the switch is: A.) open. B.) closed. o + 5V ` OV -- 5V INPUT Figure 5V + 5V OV OV 5V - 5V A.) C B.) 5V 4 OV 1 measure inductance and the Maxwell Bridge is used to measure capacitance. D.) Both are used to measure inductance. 8. The Lissajous pattern of Figure 4 is obtained by using the following sine wave signals: A.) horizontal = 300Hz, vertical Answers are on page 62, 63. - B and capacitance. The Hay Bridge and Maxwell Bridge are compared as + A inductance measure C.) The Hay Bridge is used to 10V OV C.) D.) OV D 10V E.) Figure 4. 1. A square wave Figure test on an amplifier shows that it has an ex 30 Electronic Servicing & Technology August 1986 2. Figure 4. 3. 2089 ManufacturaiPRvIRMII schematics AUGUST 1986 Product safety should be considered when component replacement Is made in any area of a receiver. The shaded areas of the schematic diagram designate the componens in which safety Is of special significance. It Is recommended that only exact cataloged parts be used for replacement of these components. RCA CTC136 chassis Color TV CTC136 DEFLECTION AND POWER SUPPLY SCHEMATIC 20 23 22 21 24 25 27 26 28 30 29 I 32 31 0601 COOS 300 IyF -'\\ 'Pool 0.13V - 57 1000I SYNC Y.T.T. SEP 38.8V 32-F NRA1 .0513 IIE6 87V 52 r v Cro ü11- OUT 9.61p 9 nos 4700T10 2405 TPI x(37 -F) pe 8403 CERAMIC 1000 RENATO r I 1,I i L _º.Bv 61 C/0 M IN TP Mn A J G 40, 0401 1103 I,MT Ç11 G1 ne= C 1401 L40 2712 AAA 39 165039 C412 240 2413- 470 7701+ 1/811 M. * 1104 6417 0.20e ,:209 .6 e, (37 F) 04111 6411 .047T 5600 2+ ,OPFT 2421 1000 vii 10e, 10 25071 ) 152 11 1/20 .6V¡. t -I 6107 6110.9 ( 1500 .49V 611001R104106 100 6111 *6112 0110 3300 752 1/72,12 rige, ZJOK I/121 TP110 12 F8102 OM F0103 I I 1 PW (AM .W 6103 7Jo0 000 /21/ R11S I9.I Of -1 RC Aa/ 0139 .1200 750 161 1/79,10 R132 750 I/M 122E3E103 I 1,0 6131.61901R139 I50K '3002 I/M I/M 79 22 BOOK .210 C120 73 .047 TP1 TO 0202 (3-F1 /,yyC3161 .O,T 3%i CRri7UJ CR403 + IYSi E64a C32014 164 TC2 l.M.76T 6413 6200 1 1 I 2400 DENOTES CHASSIS D 01T I I L - AND 02RsI1 i0111.0 J104 TP115 2104 r .754 M (37-23 R101 1K4 2117 1. C1, 100/WI USED 91TN 90101 2 P1012 6# 1101 * FI01 J108P108 :IAIM____, /L C1121 IOOOI 11 I J101 TO E5013 WED 111TH 1111007 011005, A01 TP116 y 1000I i101 MEASURED AITN SIANO. APPLIED 910,6.0 HOLD YITMIN 102. 504 E101 * GROUND. M 5(90f O6 -C3 E 1102 0(601/SS COIL 6. VOLTA6E5 * Jr. G 70 709AC E110 C109.o1T C716f Ñ1E 1104 (IS -03 F.S.PLLSEC4) rrAñ 2112: 220 rJ302-6 2105 (1-03 2104 F.5.PUL5E(-) J30g-1 (1-03 Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other hazards. This schematic is for the use of qualified technicians only. This instrument contains no userserviceable parts. The other portions of this schematic may be found on other Profax pages. Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 910E SIDE 2610+ TO L___J I L _ J CA151 SCHEMATIC NOTES. 1. ALL CAPACITORS ARE 504, EXCEPT 911£6E 1111GTE0. IMICATEO. 2. ALL 625157025 ARE 1/411 52, EXCEPT 3. CAPACITANCE VALUES 1.0 AND 0200E ARE IN 0F. CAPACITANCE VALUES BELM 1.0 ARE IN OF, EXCEPT MERE INDICATED. 4. RESISTANCE VALUES ARE IN 0115, K. 2 1000. 5.4 + 311 2170 * 044 6200 10 *101* *WA 6107 (34-N) p C501i O 23201 *6'211,020 OITA J107 130E (34-63 M I .1 , '153 MV 52X1[0 21151, )32-23 7 RR2C/ERELAY J104Á: -I E109 M O 113.1%. PAW TP112 (36-A) "`i2Y 1600 +4 R131 PW 0151 10 25012 2176 8411 07 I a 70Ó01'22 .033 .260 2133 rPAR, CR 1 ee TP710 2126: IP116 0101 0fJ ms -sf" ..IV 9A RI14 vM C111 1/711 0103 6113 T729 J (27-20 TO I 1 R42100 (120 2114 Beo 0104 9G 1' * R431 0102 - ' C11-0] (19-2] TP112 E50771 6 7Kv 25009 6129 29401 1000 25073 al01I E5011 .17V 322* 6104 L .120 Cs JP5002 16001 r 10 MI L5001 (37 F) *N (26-6) 2116 (2-X3 START PLISE PIBA 1/M 102 TO 21P240.0131 33PF 8105 I Ii79 TP7 2120 (30-6) P1o7 8111 1/79 I 65m. 5000 102,62.013 R420 .120V la 01 15015 PW24.060 1000 .12 75.106 0112 6421 ( 12109 *1 05009 25013 25010 M 560 10 7w 62 *7'9. F8407 311 V C715 BIAS 85003 í0K 117.0 IHM I M 1es 5£5005 I 1.5 I/3Y 118.1A ál S 85014 L 660 0410 0.074 2W e9 ?cool R523° r 1/M R5032 I 16 I2, R5Ú35 4500 3000 e 1 M 05021 ' 1/Ñ+ R416 1300 j r I,9a1 1 0402 T '000 .I4 R5017 I /M R5037 R5074 1:111/.,; 5.240 W OUT wag 72 TP 001001 S.63V LUMIMNCE 3.8 56 M OUT K RAY PROTECTOR es 1 05007 6415 1 .pp55pp,16R50/7 11.11. 1 0.5007 12.04 1/161 E5016 I 25006 e 102 1M I VJ R5029 egosT TP9012 11 6409 6.8p1 p4000 11108 000, F.SN TP5017 *V101 -1 I 111.2 500. PART PWRC' _ J 25005 05002 9A®1 NAPA 11.50 I36. 05011 1000 I R5034 Pz N5026 6 OR)V[ 100 P401 I/711 511( IOU C410 27 24 a J401 112,31 10 15 J90iD21 ' W 1000 IN MEASURE 2421 9900 SIZEs 1E VCO A1 1R7 2X R73 i 03 *1/24.10 1/79.16 I ' 6503 E512 Srg17 1004 2407 14.32 6401 100 3r E507 C507 j1500 i+ IN 4.974 67 1000 O,.H IS 1 2213% I ii1Ñ CR503 TO 2422 1 14 I 75 737g w% 409- IP413 TP114 I/02 24100 I/M Ix 2501 21K 82 25007 1 10 5.160 R5073 R5Ó5 3 ;NM 021/1111 6507 CN502 CO 1'409 IPW RC' I C103 1000 .974 001 1 6509 19C VEO Sa PART I 2506 25017 0.70 05031 2000 C50/ [3}E3 1,7 1 6 -g-« *1 TP*gi1 220 I/M 146Y I 12.04 1000 39 +PjQÇ) é«R ! 62,010 650 C415 .29 7 .260 .59V 1/80.2% x.. R545(33 38 37 I Jpgtt ,S;1701: 4135 5002 2E0 BIAS 101 el (5015 I 9s 25101x,1 *6513 M Ti I S5 1401 I/911 2 1 C51.07- M 58 'P41 R/! ORIVE VE 010 05001 MO 905617 11. 7000 5.17v fi 7 2406 .012.560 YOKE VERT ICA. 05077 I (5017 TO 11}/ R 5.62V 05075 65019 O.TM 70 3300 M 2` 2 0501 X AFC 0426 (32-E) 4 00F "II' .6.09 764 - 70.I0 C511... 1000T .0724 167 3000 1?0 1.7e, 20.54 OEIL Yee 2107 0179 8s 1 *DEFLECTION 771 seooT IÑ 247íl I So] 114.09 8130 E401 [9- N1 330 54 -40 180 ESA DR 3E _ r 19 AIM10.61rM5030 4,5010 91 TO VERT OUT 6603 2601 IPF 2412 U501 1/11511 120 TP TP50 K I NE 05027 220 05004 Nm OF PW RC 5)NC *PART OF Ú100 R607i20,071 3302 PART Fs/ //\ 35 34 33 , r 10 2111 + C27 -G1 2101 2105 680 16V PARR * 6102 4702 /20.100 "HOT" CHASSIS MADE> OF CORD H MAL 2089 -- ___21---,I Mmul'cturariPRv M^Dulsctë ns' schematics MTT002A TUNING SYSTEM (CONTROL SECTION) SCHEMATIC 23 22 24 25 1 27 26 f 2 3 28 KEY00AM 29 I TO 4 'IMO POIS 30 f 3 2 I 5 4 6 7 31 33 1 34 35 36 'E 6 AI I.14 SE 4 l +I Y 0603 IR 1000 /JP IN TO KEY 2 3 5 1 6 7 3 0 7 P,Ke 10 11160 (12-H1 RN e 137-6] o 9 1/88 137-01 . O.s [LBM1 MRS e.6 R.5 e.7 ([6011 EC603] 14611 33/ (R6061 221 R613 6200 (C6091- law (Cst0)p IAA( 3301 330+I g6 4 I R11/ B 1000 B55 2 v , /M K (06471 200 P N CO 3184 (37 H) Ce65y KEY w 6o 2700 o o 11841 2( SAP 2 57NC OE0 AMP 06331 1000 o 20 20 PO 50 SRI 2.75.9 0601 31A.. DU9F1 0 02 COLLECTOR 12 12K 5e T (C6371í 100I 3 2 o 10603 0675 3eI -01 (R62e] MIERE INDICATED. 7]FN11 CR624 IN 091 D (37-$1IM. 1.11E6 NRIBERS ENCLOSED IN 9RACKEIS CHIP COPOENIS. INDICATES SEIIYICE TEST POINT. INDICATE V INOICATE5 CHASSIS ARD1ND. 6. 7. 5160 .INDICATES STANDBY SIPPEN OOLTASE. 6. RN INDIACATES RUN SUPPLY VOLIA6E. 9. ALL RESISTORS ARE I/UA CHIP COMPONENTS UNLESS POWER RATING IS SPECIFIED. 10. ALL RESISTORS 50 TOLERENCE. 104E55 OT1ERYIS[ INDICATED. 11. ( ) LATE PRODUCTION E J 1149 M 5V RUN CHASSIS CDOSCTÓR3I 0 0 I 7X .110 m m 0 7 C0 76 , ,/w 137 -HI L604 4.710, 1 olI a ram 5 l 40 CR013©ru4A0, S.6V p 10001 I 0 L6G6 . _ (C650) 2 ] 41 5 .01I 6 G e BK rum 1 (CUM: 1000 C05.1 45V 010 RUN R6721R . osa 050 OR . Pr SOURCE +I 3301E J NN 171-F) 1 OMSSIS C05ECTK 519Yi5v (056o)Z c.d. CR61e 4.5V Iv P302 SNIT N 37-10 ULM (C66>1 660 2 OOM 3 8G 4 5 6 m 2 2 02A ! STAN MY SLPPLY FRCP NAIN APPLY NOTE, C1C 130 0003519, 2102(40-F). PROM PY 01PUR, 15 A/0-5T0Y 9P0LY CTC 130 C -518T (65-5I. I13NT7KBD013H KEYBOARD SCHEMATIC 0 0 m 0 0 0 0 0 W 2 2 H 7 w 12 2 -- H VOL C66)(C8119.1= .01 IN 21. SV RIN KBDO35C KEYBOARD SCHEMATIC r a- A-49_,r a l r B- ^--1 H1 L ----JD . IK CR607 srrñ VOL e e 7 e IL Product safety should be considered when component replacement is made in any area of a receiver. The shaded areas of the schematic diagram designate the componens in which safety is of special significance. It is recommended that only exact cataloged parts be used for replacement of these components. 1 H D 32Ú59 3 _1'T KB0021C/ CHAN F CR612 C)1. 17dT 190011 (C6'( R67, 4700 0 0 0 1e C6>J(064,1 L605 fe 1 22K) (37-01 K80027C/E KEYBOARD SCHEMATIC m m 34 $4802 SIRS 0840 D15I2W0 R655 000 (37 FI ' 0 0 m 0 0 m W Z w 2 W W 016431 666 1 30V 006160 /,1 IN 100AF RN (C62011 10001 (37-N) 33 LO (37-61 F--. (3/-F1 33 2 16 7U1 R051 CRS, 1r6 C605+ (K101 VOL LC IC670) 1000 ISRI 3 17 35 0101 IN il OLnYIE (8610] 1700 - an a6193 1 1 OSD 720 vK 4.76 03010 CR605 MEOW (1634 0664 106301 37 R6M »66 NN 13/-F1 GCE CR6o3` .01 1.3.0 VERT 7? IS¡ 0605 IK (C6231I 186321 (C6171í 1000I K1AL 5T51 (0659 (06221 2200 (R5311 (86201 1000 12511 OFF .047 ICI 0804 170 Y RW 30 Aux (RIM 6653 106'31(7í-F1 o 6 I L601 r SYNTHESIZER/MICROPROCESSOR 1--1 3 [COSA: 1000 2/1/K C644 C6/1L 4700 7 (06521 (R6491 106K 77 500 EXCEPT 4. S. 6K C633 21 - .64TI (116451 1000 137-F1 000 m m m .... K (COQ] RF 5Y1T01 AUX AUX MD ([6311 09LS. 5.1000 CAPACITORS ARE 50V CHIP COMPONENTS U10.E55 VOLTASE RATIOS IS SPECIFIED. CAPITANCE VALLEs 1.0 AND A60VE ARE IN OF, CAPITANCE VALUES SELON 1.0 ARE IN ALL 3. II (C60711 0602 CET TV 1000 OIIRN GCE 2. e 24011 CHAN DWI U601 [C,151 - 2! L632 .033 S. s [01201 1000 L0/K 022 6 RESISTANCE VALUES ARE IN IC0351 PAh 24 T o o !E 6 AFT 6,I mica K Sv Y lE01 N1 IN 270 CRI 1. 5600 /eY (1167011 40 2 e ER6251 [29-61 SAP 3 4 NCI 5v NENOrv 15 11001 5Y IR 1000 C671, SCIEINTIC NOTES - .» v1Y 4 418 40 C880 (C6301 1000 0025 470 I/911 C 4 OSI AFT OUT 10001 8626 4x 03 100K Ri1 R604 ' J 7 553 AFT ENABLE 552 33K (C61Uy 47K B r-,' [06461 470] 225 R603, i: 954 6200 (86001 0602 L I3 PROCESSOR K17 226 CIIDun E0647). IC61.i ,/K (C61x 1/K (86071 10K 6 7 3.,3 M,6 6200 R615 `/: IC61_ .--} MAL., $6 s 5 Ie1 5w0 6 8612 9200 U6061- 3E6 SEN 3 2 F.e R611 1 OR gr $6 U602 SWITCH/ TUNING VOLTS BAND 10 RIN 137-FI uc KM y2 (86371 0.01Í 40 3 P2Ke1 _MN! 17-rL,' ] 5 84 !7 1R631100K LE/OF 39 A 300 CR609 1 ALTERNATE 2 9 This schematic is for the use of qualified technicians only. This instrument contains no user-serviceable parts. CR610 38 1 r MTTOO2A Tuner Control (C67/1 37 2089 0 0000 O IF JUT/A6C 32 I VIIIH AUTO 5TERM eTEPM POWER Product safety should be considered when component replacement is made in any area of a receiver. The shaded areas of the schematic diagram designate the componens in which safety is of special significance. It is recommended that only exact cataloged parts be used for replacement of these components. ADD 19x01 AUDIO 0 Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other hazards. STEPS This schematic is for the use of qualified technicians only. This instrument contains no user-serviceable parts. STEP The other portions of this schematic may be found on other Profax pages. IÌ Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other hazards. The other portions of this schematic may be found on other Profax pages. 55D013 Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 MTTOO2A TUNING SYSTEM (RF SECTION) SCHEMATIC 2 1 5 4 0706 7 I 12 I I 5 R307 1312 2j121eM0 L301 i Io6 _w -.y i0 8302 Uf JA1RR (R3021 i IOOK n 0.301 109 6335 10366] 1 1800 I« (63031 1000 /113013 29 1000 309 4701 0311- IQ /->A 1306 (C3023 170 1701 6 (64091 10,70] 104111 470 19 IOK 1112 1000 L106 0306 [C10911 1402 IC,r91j les loo (0300] 0.01 [15-10 10K 1/eY I«61 (R9091 AGC (93113 10K 003191 n 5.6 I,e1 1 .073 47 ("IM (C12331 0.210 103081- 1000T 250s 13 1 n 390K (61101 TP101 (04213 2200 1_6 11125] RIIGI 1.7 P402 9 n (03051- 17 0.02 0211T171 1 1 270 1/1V /Is 16 1 1000 C172 [15-N1I 5005 15 IC108] fC1o11 23 470 ev 0.56 IR305] -63~12 10131.1 C312 1_ 1 e- 6407 ' KK 4701 063171 2200 B F8331 1a I iscr, (C301] L311 3.3 A .6 (RF SECTION) MTTOO2A 150 BOARD 1 (C317] 4701 fC3011- -. 4701 0707 5702 75 10 300 pell 00 --+E--1 ¡I 0 IIOD, ttt C702 1100 C710 1200 7031 12001 I C711 3.3 F5702 F6701 -1-i 0705 600 IN I 470 (00031 C6501 27' 1702 f L00 LeY 13701 1.6109 -7F *R704 3.9 RED 2 RED L505 [C503] (CSo1]I 7700 C517(1 CRw2.-'000 'SI(C5o2] a0 I (R5061 i6« 29 11508 1509 L510 170 0.01 laios 8507 270 [C509] 0.01 (0511] I/4w 8101 X29 CR507 1103 Sn Cß102 Cß103 (C1121185111, fß5101 O3[ 1/e3 5.6 CRSpi oa (C1371 (C1023 10001 (R5151 2700 -- (C5203-1 (63021 110 e1,10.10. TC110] 470 (01191 (01201 MC LOCAL n 1C1311 68000 10 Cß108 Cß113 CR115 (91071 et (0130] - 001131 170 (01111 101 6131 200 (Cls0) oX R109 170i f 17011 170 101261 Opt ICI031- ICIOÁ OCI071 470 [1128]. .R7'o°]K 023 S LI1107 N ),7D'I(C107]T 070 2200' - 0101 [C1081 IC1051 170 L101 0101 200 29 (65171 LOO 1710 1102 1101 Cß101 13 CR510 1003 (65031 2200 0.011 INNy [CS 51 (85121 0220 10aK [C5011í - 1000 rtslo3_ 100 1210 6e OK 1511 laso C5a1 O(05071 005041 7700 (050,1 (0002] 701 1506 1501 (05101 105091 2700 2700 (65051 CR503 2700 I[CD0iiT , F650 116021 L001 1.6140 15Ó'2K 1/16 AMP 501 O R001 035 0701 0501 31/022 RF IC2771; (C0023 n (CI221 470 I06 470 .---IE- Tv I01341 10001 62 0.01 (0L15, 1701 F-- 3F ARP r-- 470' WL0/001111I 0101[) 5701 (0201] 100 I02221 1500 L20 120 íR2031 (9206] TOOK 1609 n n TO F5 CABLE/N0ß41 [9202] F0201 2.7Hp CR202 'C 170 (C232] 470 C2071 (02031 1701 2700 °S [02051 (C202( 470 G 1210 1201 (0205] x2231 ,70 i 1 N (000 0.5 B3/91 1207 112241 [C2181 0201 CR201 lo SCHEMATIC NOTES, IC521]- RESISTANCE VALUES ARE IN OIM5. 2. ALL 3. CAPIIANCE 1207 ro 152061 2705 n 1C2281 .- 17aT I 1%Ñ (C700] 82 [R212] 1=11EN NUMBERS ENCLOSED IN MACKE'S eI 470 {] mp1Z 1213 ,JOr IR219] 2700 (009 63 (0211( E8202 1701 INDICATE 15 SPECIFIED. 0103 INDICATED. 01731 CHIP COPONENIS. ([1351 [R1090 85 LOCAL 2 060. 5 (C4011 30 INDICATES SERVICE 1E51 POIN1. 1 6. 11OICA1ES CHASSIS COLD GRIMM. p IIOICATE5 CHASSIS HOT 603510. 9185 =INDICATES 51,04001 APPLY v0L1A0E. 9. RIM =1NDIACATES I0. ALL 6. 7. I (82131 2200 (0212). K41000 C093010015 1ß4E55 0OLTA6E RATING CR201 IOOK 1701 470 C111P VALUES 1.0 AND 0600E ARE IN pF. CAPIIANCE VALUES BEL011 1.0 ARE IN tF. EXCEPT WERT 5. (C2151 CAPACITORS ARE 50V 4. L211-. (C2333 RESISTORS 0C12615 ARE I/61. CHIP COMPONENTS MISS R110 I1K ([1251 1701 RIM SUPPLY VOLTAGE. PONER RATING CC1243 n I5 SPECIFIED. (CITI] 11. ALL RESISTORS 59 IOLERENCE. UNLESS 011ER5ISE INDICATED. (C22011 ,701 0121 200 170 (01221 011221 200 1 170I (21123 2700 1206 (021 .700 (C1311a 06217] (R2233 1000 1. [11141 50 r (0112(, 10001 N, 470 OR I (82111 1000 C9207 81 H , ® p 03 I(014431 il .34.1 (c 1 47°I 471 10 83 02 01 85 10/9 10v .70= (C139/1 170= í6V SOURCE 54 SOURCE 454 (15-10 1 TO SVNTIE512ER/MICRO0ROCESOR (CONTROL SECTION] (39-8) Product safety should be considered when component replacement is made in any area of a receiver. The shaded areas of the schematic diagram designate the components in which safety is of special significance. It is recommended that only exact cataloged parts be used for replacement of these components. Product safety should be considered when component replacement is made in any area of a receiver. The shaded areas of the schematic diagram designate the components in which safety is of special significance. It is recommended that only exact cataloged parts be used for replacement of these components. Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other hazards. 2089 hazards. This schematic is for the use of qualified technicians only. This instrument contains no userservicable parts. This schematic is for the use of qualified technicians only. This instrument contains no userservicable parts. The other portions of this schematic may be found on other Profax pages. The other portions of this schematic may be found on other Profax pages. PROFAX {titi Manufacturers schematics Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 M9nulxtur.ri schematics v Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 2089 esaw McRuf'cturniP schematics R© on 2089 CTC136 SIGNAL CIRCUIT SCHEMATIC r 1 4 2 ,. IF 5 0303 A 9AN FILTER IF U1001 L306 e7 P^ R31B IS 2200 eo 20 TIMO 0803 A11 56 1000 S. m I/ w AIM 0304 390 20 /98 1/98 cnir 8 8.2 TP s. C302 "°'.01Í 1000 56 + 132-61 . rpm I C / íO000 E31I F93o01 c37/ 6311 TP31 19 46 6.030 17'4 132 -FI * R117 o /*/' L/ . 1 41 PART OF U1001 -p596- MUM VCC 43 .6 6- E _it5 TO F'----HIt^+_ F.S. '] vQ/MU1[ EROS SOUND M JY2003 6.52V 39 0 PIASE1.14265 131-11] (32-E1 6.520 7e Y TP 01 2.2 100Pf C215- O 6210 C207 1/2W 95v I-- 2.2 0202 1/26 AUDIO F 0207 0213 I7K 56 ]9 035V 4.65 -1` IF 06C 621 1/13°° N O IsOR F 15.085 1/711 1 63 2 w PIN 5 EXCEPT MIERE INOICA,ED 4. 6(5(51ANCE VALUES ARE IN 0915, R= 110113 PULSE 132-001 -61 5.1, 3600 vol _ 229E 12 551: 0 15 470 R700 J 0702i 1/9,29 .011 10 1P702 06502 (26-C] CR701 O (32-G1 O1+ A 3.31 P70110 -T 0 0 0 0 E4039 E42049 012059 E4206 E1 I E4201 5 4 3 5.72 0150V 0.1 (33-10 1P209 I 1900 C202 771 I01F 1,20 1/ i DPW * 3 6137 T TO 1OR COLOR FIK 0081190411 R1221 (32-F1 .9V (32-61 7 pi1 E420e J901 971,, 8710 .091,/98 SIN 70K 1/98 .4 71 CR707 (703 1 .89 LIMIT 132-61 5 089 132-03 4.810 .1 77 132-C1 I TO (42079 9FÁ1( 87031 .01+ (9-H1 2700 7a * 9215( R1202 29 GACK LESEL ri I 1 .1289 (27-51 I 19016001 FAC J * 2217 22K C0MP0511E C IVO51/[ v1gEO 5740\ E701 n5 -.l 17/-E] TO .6.89 14207 tOK TO E106 4]00 R1203 10 E503 4911 BLAIK 127-A1 470 R2021 1a PART aF 59 .°2os6T 61701 1 Y ' 25v 4700 TINI CRI i5Y 0201 ATTEMMTpt y 6.105 132-07 6 .31 701 01220, IRA 100K t/98,26 .. ; + 17011 si 0707 BEM LIMIT 6721 4 3- 1 COL 07131 /9,26 1/9829 C27J1 .16:r CR700 K 31 EXCEPT 044ßE NOTEO. APPLIED, 9V 132.-C1 9 C211 26'/ 1000. 6V 6 .99 t/98 X CHASSIS GROUND. DENOTES 6. VOLTAGES MEASURED WITH SIGNAL APPLIED. AID 560410 00.0 011109 106. 7. WAVEFORMS TAXEN NITM REVEO RAINBOW SIGNAL 6710 w 51 552 12141 B0 00706 C707 .01 GUADRATURE .011 7061 13 6709 330 OUTPUT 5. 6212 i ,/98 rn 15 TP701 0701 TO 359 V .;SIN C2420!5 w Ph 10yF L-ïF1A02 Cí201 "C2081, 0205 T i rv 4.089 11 SCHEMATIC NOTES, I. ALL CAPACITORS ARE 50V, DICER, WHERE I11OICA1E0. 2. ALL RESISTORS ARE I/AW 59, EXCEPT WHERE INDICATED. 3. CAPACITANCE VALUES 1.0 OTO ABOVE ARE IN pF, CAPACITANCE 9ÁL105 BELOW 1.0 ARE IN 1F, 171 0716 w. C212T G ad I32-FI 98 H SHARPNESS 0730 5600 200 0334 1)X 0705 2.564 52 R705 L701 SHARP 6217 27 Ij° 17 PEAKING + 6207 1500 1 C721 101N 359 1x5Y OK f32-6] C21] 19-0) C4071 .00621 07 17 AÚ010 1 700 0716+ I AIV - , 8720 190 .90 0727 (32-01 820 10 7901 C708 CR703 O O PIN 9 1 * 01709 2.20 28 R204 5600 t 1pF ` 10 C2WF 06 10 0211 p139* 26 - OF 2.20E T 6800 1/21 .01 1/98 (702 679 001110051 290 5K 89K Tp 05 00702 0701 1/III/ C711992 IPW RC tyf7 R I24-6) r PART 10 0708 3300 21.9 ji, L703 .01+ R712 470 .9V f37-61 8011 1/98 0606 4.90V 210 .974 (050 690 713 E703 (16-F1 TO .9V (32-G] O (T5017 (33-9] IJ901 10 PY REM -IA Manufacturers' schematics IP RepoIII OR PS REN -IM MEN 411 TUN NG 515TEM 15 USED Product safety should be considered when component replacement is made in any area of a receiver. The shaded areas of the schematic diagram designate the components in which safety is of special significance. It is recommended that only exact cataloged parts be used for replacement of these components. Use of substitute replacement parts that do not have the same safety characteristics as recommended in factory service information may create shock, fire, excessive x-radiation or other hazards. This schematic is for the use of qualified technicians only. This instrument contains no user- AUGUST 1986 servicable parts. Schematic No. The other portions of this schematic may be found on other Profax pages. RCA Color TV, CTC 136 chassis (includes tuning system schematics) 2089 Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 I/211 efen 1/06.2X 1 0729 07017P711 l' R810 1000 41805 10810 +.012 ea C802 I/0I I 1402, PIN 1 .9V (30 -FI + 1.8109,. 9.019 V1 '°li 2 TP309 1P202 C203 O ONM 11.1V 1P205 220 0-50UN0 4.05 259 0.210 CR201 R209 2 1000 0326 470 0.791 C6202 M 300 CONTRAS, ,9ALAMCE .01T 41711 1 /i 0716 0205 10.3 11.IV LUMINANCE 0431 TO S0 1/9842% 4 71PF C81289 0714 0707 AF1 IO 0 IF 16301 0201 DD10 MP E 132 -FI 19323 IF pET JW30 E117_127-61 .9V 132-61 T1 PRESET C216 1.16V 6 T0811 +.01 2.2 oh f32G] 113211 431 2 n0 1101 C911 9 111171F / 12V 4 4 7000' 7 C313 V CaOR 34 3 07 1901 so 29 T. TUNING 5191EM 1310 1 5.' 0713 1 R812V _ C312T 120 C376.i 3 F302 T 8.89y PvRR0Á 2201 OOOT w I AGC 4r; 1 231914 } 39K } E111 10 E101 9-11J--9- F.3. wLxf-I -MI 1 AFT 131 TP31R9 r .26V ß2-E3 48 fTP603 3000 L703 TP701 6321 .01+ 1 DEFLECTION 12 E5077 [33-0] 6611 3.56186. 1( 9700 0315 U1001 PART OF 1 TO (32 -GI R325 18 1 C308 TP 3a17 AFT L312 7.77V 18 1P710 011 3301: -tCNOSSOVER ' Y 470 t - - - -, L- AGC 2.2 110335 I ÁG0 9 6321 1000 1303 :,:d á 2,1;i A6C 22 7.671 -11 0813 031 .022T E312 F302 A I R315 I 03091 41 P RC 1PW D 1 0320 870 I 5.410 23 51 C3071 5 10 98 .nTl/w1 { ÿ, 6312 .9V 1/98 E301 1 10 C939 1 21 6307 17 L802 / OET 9301 16 1 9 C13161 41E00 I 6 - 2,0120 T e.],P ].89 0301 1000 0 '301 ---3OIF1 D 9 0t 15 14 LLLL P305 T 13 12 11 IP OF 15 T 1e 9 8 7 ] *PART 0301 6 i Reprinted by permission of RCA Consumer Electronics Copyright 1986, Electronic Servicing & Technology, P.O. Box 12901, Overland Park, KS 66212 IDEO -i)- Capacitance, logic and more. For less. Literature Editor's note: Periodically Elecpany, has published a 4 -page tronic Servicing & Technology "Laboratory Power Supplies" features books dealing with subjects Sorensen, a Raytheon com- brochure describing key features and specifications for 58 models of its resistance, voltage and IEEE -488 programmable power of interest to our readers. Please direct inquiries and orders to the publisher at the address given, rather than to us. supplies for laboratory/industrial Principles of Digital Audio, applications. C. Pohlmann; Howard Included is the new listener/talk- by Ken 288 pages, $19.95 Sams; W. er 488 Micro DAP digital -to softbound. analog interface unit for computer Much of the information in this control of power supplies. is being published for the book Circle (125) on Reply Card first time. The reader is introThe latest edition of the Philips duced to the integration of digital Test & Measurement catalogue for electronics and sound, a relatively 1986/87 is now available. The new concept to many in the audio 250 -page catalogue provides field. Illustrations and formulas details on Philips range of test in- enhance the eight chapters that struments, with full information cover digital audio basics, on all new products introduced in fundamentals of digital audio, digital audio recording, digital the last year. audio reproduction, digital audio Circle (128) on Reply Card More than 200 new additions to Keystone Electronic's component and hardware lines are featured in a recently published "1986 New Product Supplement." The 12 -page multicolored catalogue details all technical data, specifications and illustrations on nine major new product groups that include patch cords, test Diode check Built-in bail Anti-skid pads See one now at your local Beckman Industrial distributor. DM25L... $8995* ginning." Circle (127) on Reply Card A catalogue from Automated Production Equipment features seven pages of PCB repair equipment in full color. Of special interest is the model SMD -2000, a complete repair and rework center Circle (128) on Reply Card TTL Logic Probe: 20 MHz Hi/lo/off indications Detects 25nS pulse width Capacitance: 5 ranges (2nF to 20µF) hFE (NPN or PNP):1 range (1000) DMM: DCV-5 ranges (.2V to 11(V) ACV -5 ranges (.2V to 750V) DCA -4 ranges (200µA to 10A) ACA -3 ranges (20mA to 10A) Ohms -7 ranges (200 Ohms to 2000 Megohms) Continuity beeper media, error protection, the compact disc and "a new be- leads and accessories, jumper cables, ceramic spacers, steel hole plugs, nylon cable clamps, rubber and vinyl bumpers, and panel hardware. The publication also details expanded listings of Keystone battery holders, battery clips, plugs and jacks, fuse clips, washers and grommets. for conventional as well as surface mount PCBs. Also featured are models of track repair kits used to repair damaged circuitry, plated through holes and laminates to PCBs. Now, a fully-loaded DMM combines capacitance meter, logic probe, and an hFE meter, all for the price of a DMM. a raw_ Published by Howard W. Sams & Company, 4300 W. 62nd St., Indianapolis, IN 46268; 317-298-5400. Pocket Digital Multimeter Techniques, by Homer L. Davidson; Tab Books; 368 pages, $14.45 paperback, $22.95 hardbound. By an author well-known to ES&T readers, this sourcebook provides hands-on guidance for troubleshooting, with your pocketsize DMM, everything from small electronic components to complex cassette players and TV sets. There are tips and shortcuts, drawings, diagrams and trouble- shooting charts to fortify instructions for checking diodes, transistors and ICs. These also illustrate 15 procedures for testing the color tube chassis, 51 tests for checking solid-state color televisions and 21 tests for B&W televisions. Eleven 1 -minute tests for portable radios, nine checks for AM-FM-MPX radios, 10 speaker tests and 12 simple phono repairs also are reinforced by many of the 390 total illustrations. Published by Tab Books, Blue Ridge Summit, PA 17214; 717-794-2191. "SUL, August 1986 'Suggested list price(SUS) with battery. tent leads and manual Beckman Ind..0 tr!a! M Beckman Industrial Corporation A Subsidiary of Emerson Electric Company 630 Puente Street, Brea, CA 92621 ( 714) 671-4800 © Copyright 1985 Beckman Industrial Corporation Circle (13) on Reply Card Electronic Servicing & Technology 39 Satellite receiving antennas TVRO antennas and a family of strange terms: birds, feeds, dishes, hooks, horns, GSOs, LNAs, LNBs, LNCs and GASFETS, to name a few. Ph C, By ,. James E. Kluge For the uninitiated, shopping for a satellite receiving system can be confusing because of the acronyms and jargon tossed around by those in the trade. Even the technically trained person who doesn't work every day with birds and dishes may welcome the following review of basics before becoming involved with TVRO antennas and how they work. Television receive only (TVRO) signals emanate from a satellite (bird) out in space. The signals are first beamed up to the satellite (uplink) from a location here on earth. There, the carrier frequency is converted by a transponder and the signals transmitted back down to earth (downlink). Originally, the satellite is launched into space on a rocket or other space vehicle and then maneuvered into a geosynchronous orbit (GSO) and positioned at a predetermined longitude relative to the earth. The orbit is sometimes referred to as geostationary orbit. This is a misnomer. A geosynchronous orbit is a circular orbit directly over the earth's equator and 22,300 miles above it. This the distance necessary to is. James Kluge is Technical Editor for the Winegard Company, Engineering and Research Division, Evergreen, CO. 40 Electronic Servicing & Technology Geostationary -lGeosynchrouslOrbit _ Satcom F5 143 W , 'w rr. Saloom IR 139 `e -1144 4 W Satcom FI >il 135 W Saloom F3 131 ' 22.300Mesl W Constar 04 127 W \+A "%A'. Westar 5 123 Wester 1/2 79 W W Saloom F4 83 Salcom F2 119 , W Anik A3114 - IRWIN'[(' Comslar 03 87 Westar 3 91 W W Amk8109 _ Comslar0l/0295 W An1k 01 104 W Westar 4 99 W W W >141, W 000 Figure 1. All of the domestic television relay satellites are located in an orbit directly above the earth's eauator between 79° west longitude and 143° west longitude. SATCOM F -3R EIRP @ 131 W NOTE: EIRPS FOR TRANSPONDERS 3. 7. II. 15. 8E AT LEAST 2 tl8w HIGHER THAN SHOWN 19 & 23 WILL SAN ANGELES EIRPS 'dew) ANCHORAGE JUNEAU 28.0.28.7 - 30.431.3 DENVER 34.8 HONOLULU -- 25.5 Figure 2. EIRP, effective isotropic radiated power, is a measure of the relative strength of the satellite TV signal expressed in dbW. Each satellite has a different coverage pattern and in many cases different transponders on the same satellite will show a different EIRP. Where the signal is highest (strongest) is called the boresight. August 1986 Exclusive, triple patented dynamic cap and coil analyzing ... guaranteed to pinpoint your problem every time or your money back with the all new LC75 "Z METER 2" Capacitor Inductor Analyzer balance the gravitational force of the earth with the centrifugal force of the orbiting satellite. By positioning it over the equator, it orbits in synchronism with the earth as the earth rotates on its axis. Thus, the satellite appears stationary in orbit when viewed by an observer here on earth. This is necessary so that an antenna pointing at it from a location here on earth does not have to be continually repositioned, as with tracking antennas, but can remain stationary once installed and positioned. The geosynchronous orbit also is called the Clarke orbit, named after Arthur Clarke, who in 1945 first proposed using the GSO for global communications. Once placed in orbit, the bird is said to be "parked." Its precise orbital location is allocated by the FCC, which is the government agency that coordinates, along with other North and South American countries, the number and location of geosynchronous satellites in the Western Hemisphere. In addition, it also sets technical operating standards. Satellite locations are designated by a longitude corresponding to an earthly longitudinal plane that extends out from the earth through the parked satellite. Patented $995 The "Z METER" is the only LC tester that enables you to test all capacitors and coils dynamically plus, it's now faster, more accurate, and checks Equivalent Series Resistance (ESR) plus small wire high resistance coils. Eliminate expensive part substitution and time-consuming shotgun- - ning with patented tests that give you results you can trust every time. - Test capacitor value, leakage, dielectric absorption, and ESR dynamically; with up to 600 volts applied for guaranteed 100% reliable results it's it's triple patented. exclusive Save time and money with the only 100% reliable, in- or out -of-circuit inductor tester available. Dynamically test inductors for value, shorts, and opens, automatically under "dynamic" circuit conditions. Reduce costly parts inventory with patented tests you can trust. No more need to stock a large inventory of caps, coils, flybacks, and IHVTs. The "Z METER" eliminates time-consuming and expensive parts substituting with 100% reliable LC analyzing. Turn chaos into cash by quickly locating transmission line distance to opens and shorts to within feet, in any transmission line. Test troublesome SCRs & TRIACs easily and automatically without investing in an expensive second tester. The patented "Z METER 2" even tests SCRs, TRIACs, and High -Voltage Diodes dynamically with up to 600 volts applied by adding the new SCR250 SCR and TRIAC Test Accessory for only $148 or FREE OF CHARGE on Kick Off promotion. To try the world's only Dynamic LC Tester for yourself, CALL TODAY, WATS FREE, 1-800-843-3338, for a FREE 15 day Self Demo. - Call Today Wats Free 1-800-843-3338 NCQ 3200 Sencore Drive Sioux Falls, SD 57107 605-339-0100 In SD Only innovatively designed with your time in mind. Circle (14) on Reply Card August 1986 Electronic Servicing & Technology 41 Tte bus iress end )1 a feedhorn is shown :hrough ha derhra:ad-aluminum sur - r fase of the l seta-; ref ected energy is deamec intc l! e rvaveg aide opening in :ha center o 1-e lieeciorn. The pz lar antenna mount allows the dish to rotate on its axis defired by the square-cross-sectior structural element. The re -lector is attached anc pivoted at the ends of this element as it sweeps the anteraa through the Clarke orbit. The elevahon angle, when pointing south, is adjusted by the positbning devices in the lower foreground. linear motor -driven ac-.uator causes the dish to rotate on i:s olar axis thus tracking the geosynchronous orbit across the sky as it searc1ea for the desired satellite. A 42 Electronic Servicing & Technology August 1986 A TVRO receiving antenna must be pointed at a particular satellite to receive its signals. You must know the bird's location in degrees west longitude, your location in degrees longitude and latitude, and after computing the elevation and azimuth angles of the antenna axis, point the antenna in that. direction. A convenient alternative is to use a polar antenna mount. Polar antenna mounts are so designed and constructed that they permit the antenna, by simply turning it on a polar axis, to sweep or track the geosynchronous orbit between its visible east and west extremities that generally are determined by the earth's horizon. Such an arrangement allows the dish to be turned by a hand crank or a linear motor -driven actuator, the latter being powered by a do motor and controlled remotely at the receiver. Once the antenna is set up and adjusted, the signals arriving from the satellite strike the metallic dish reflector surface and bounce off in the direction of the feedhorn. The feedhorn is supported by a buttonhook-shaped device. The surface curvature of the dish is such that wherever on its surface the energy strikes it, that energy always is reflected to the feedhorn, which is located at the focal point of the parabolic-dish surface. A reverse analogy would be that of a spotlight in which the light energy emanating from the bulb filament located at the focal point strikes the reflector, and from any point on the reflector surface the beams of light radiate out parallel to the axis of the reflector (and, of course, parallel to each other). Because the signal energy from the satellite arrives in parallel beams (or, technically speaking, as a plane -wave front), the energy is reflected toward the focal point and collects at the feedhorn, which is placed at the focal point of the reflector. The electromagnetic energy arriving at the feedhorn is channeled into a waveguide, which delivers the signal to the LNA/ LNB. The low -noise amplifier (LNA/LNB) is physically connected to the feedhorn to minimize any interconnection losses. Analyze defective waveforms faster, more accurately, and more confidently every time or your money back - CHANNEL A CHANNEL with the SC61 Waveform Analyzer $2,995 Patented If you value your precious time, you will really want to check out what the exclusively patented SC61 Waveform Analyzer can do for you. 10 times faster, 10 times more accurate, with zero chance of error. End frustrating fiddling with confusing controls. Exclusive ultra solid ECL balanced noise cancelling sync amplifiers, simplified controls, and bright blue dual trace CRT help you measure signals to 100 MHz easier than ever. 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Simply connect one test lead to any test point, push a button, for test of your choice, for ERROR FREE results. To see what the SC61 can do for your troubleshooting personal productivity and analyzing confidence, CALL TODAY, WATS FREE, 1-800-843-3338, for a FREE 15 day Self Demo. - Call Today Wats Free 1-800-843-3338 SNCOF 3200 Sencore Drive Sioux Falls, SD 57107 605-339-0100 In SD Only innovatively designed with your time in mind. Circle (15) on Reply Card August 1986 Electronic Servicing & Technology 43 The electromagretiï motor atop the teedho-n assembly rotates the signal elemelt inside the -eedncrn from one positioi :hrough 90 to a -tether when switching from Jeri ice' to 1c-izontal signal à (or vice ve -sa; as the 24 channels at the receiver are segue -It all' stepped through. In conjunction with the TVRO antenna (pointed at a satellite in the geosynch-onous orbit, see Figure 1), a buttonhook device supports both the feed, and the dual LNB assembly that converts as a block the frequencies from all 24 transponders: 12 vertical channels in one LNB and 12 horizontal channels in the other. typical LNA, standing on its feedhorn flange, shows the coaxial output connector at the opposite end. Dc operating voltage is supplied to LNA circuits via the coaxial cable and connector. It is the feedhorn end of LNA that terminates the waveguide where electromagnetic energy is converted to a signal voltage at the LNA input (inset). A d.l Electronic Servicing & Technology August 1986 Now test and restore every CRT on the At this interconnection point, any signal loss is critical with regard to adding noise to the feeble signal. Once the signal is amplified in the LNA and converted to an intermediate frequency (IF) in the down converter, the handling of the signal and possible introduction of noise is much less of a problem. Downconverters, which translate the frequency of the signal down to a much lower frequency, are generally of two types: 1.) a tunable downconverter, or 2.) a block downconverter. Early receivers generally employed a tunable downconverter with single-channel output at 70MHz controlled remotely at the receiver. This type downconverter operates similarly to the tuner (channel selector) in a TV receiver except that in the case of a TV receiver the tuner is mounted within the same cabinet receiving its power and delivering its IF output over a short coaxial cable to the main TV chassis. In a TVRO system, it is necessary to locate the tuner downconverter at the antenna attached to the LNA and remotely tune it, using a variable do voltage from the receiver (electronic tuning). Newer TVRO systems employ block downconversion. It has the advantage of making available, simultaneously, all programs from a given satellite instead of only one at a time. This means that in a given household, one member of that household can watch one program while the other members of the household can watch programs of their own individual preference. Of course this necessitates that each viewer have a separate TVRO receiver and a TV set or monitor. The basic difference between the tunable converter and block converter is that with the former, the tuning is accomplished at the antenna whereas with the latter the tuning is done indoors at the receiver. In either case, the first downconversion is accomplished at the antenna. The tunable downconverter/ LNA assembly (commonly referred to as the LNC) accept the 3.7GHz to 4.2GHz signal, tunes to market ... without ever buying another adaptor socket or coming up embarrassingly short in front of your customer ... or your money back with the new improved CR70 "BEAM BUILDER"TM Universal CRT Tester and Restorer Patented $995 Have you ever? Thrown away a good TV CRT, data display CRT, or scope CRT that could have been used for another two or three years because you had no way to test or restore it? Lost valuable customers because you advised them that they needed a new CRT when another technician came along and restored the CRT for them? Lost the profitable extra $35 or more that you could have gotten for restoring a CRT while on the job and locked in the profitable CRT sale later? Avoided handling profitable trade-ins or rentals because you were afraid you'd have to replace the picture tube when you could have restored it? Had a real need to test a CRT on the job, but didn't have the right adaptor socket or setup information in your setup book? If any of these things have happened to you, CALL TODAY, WATS FREE, 1-800-843-3338, for a FREE 15 day Self Demo. "BEAM BUILDER" is a trademark of Sencore, Inc. SNCOR Call Today Wats Free 1-800-843-3338 3200 Sencore Drive Sioux Falls, SD 57107 605-339-0100 In SD Only innovatively designed with your time in mind. Circle (16) on Reply Card August 1986 Electronic Servicing & Technology 45 one of the 24 transponders (each 36MHz wide) and converts it down to 70MHz. The block convert- ficult to handle. By downconverting the frequency, standard MATV cable may be used, which is er/LNA assembly (commonly economical and readily available. referred to as the LNB) accepts Downconverted frequencies may the 3.7GHz to 4.2GHz signal and vary with various manufacturers downconverts the entire 0.5GHz and even between products of a band as a block. This block of signals is then transmitted over coaxial cables to the tuner indoors where the individual channels are selected for viewing. You might ask, why downconvert? Why not simply transmit the 3.7GHz to 4.2GHz block indoors to the receiver and, there, tune the signals you want to view? It's a matter of economics. The coaxial cable required to transmit 4GHz signals without appreciable loss or attenuation is costly, bulky and dif- corrugated feedhorn, showing the rotatable signal element in its vertical position to receive vertically polarized signals. The signal element inside the feedhorn has been rotated 90° to receive horizontally polarized signals (below). A given manufacturer. The industry is standardizing gradually as it matures. The frequency block, 950MHz to 1450MHz, seems to be emerging as a de facto standard. Located between the feedhorn and the downconverter (electrically) there must be a low-noise amplifier to boost the extremely weak signals from the probe or antenna element. The purpose of the LNA is to amplify these tiny voltages about 40dB to 50dB without adding a significant amount of noise to the signals. State-of-theart gallium arsenide field-effect transistors (GASFETS) [pronounced gas-fets] are employed to accomplish this difficult task. They are relatively expensive, but at this point necessary to do the job. In addition to specifying LNAs by how much gain they have, another equally important specification is noise temperature. It is an indication of the noise power generated within the LNA and is expressed in kelvins (K). We use temperature in this case because the noise -figure numbers are getting very small. For example, a temperature range from 75K to 120K covers a noise -figure range of only 1.0dB to 1.5dB. The noise temperature rating is cor- Uplinks and downlinks How the satelliteTVsystem works r GEOSTATIONARY SATELLITE DOWNLINK SIGNAL FROM SATELLITE 3.700 lo 4.200 MHz UPLINK SIGNAL FROM EARTH TRANSMITTING STATION 5.900 to 6 400MHz iTV Satellite STUDIO Dish Antenna There are over 16 geostationary satellites in operation. These communication satellites are basicaly relay stations in space. The transmission of the satellite programming is carried to a satellite uplink station (via cable, microwave or combination of the two) then sent from the uplink antenna on the C -band (5.9GHz to 6.4GHz) to the transponders (also known as microwave repeaters) on the desired satellite 22,300 miles above the equator. The transponder receives the signal, amplifies it, then changes the frequency to 3.7GHz to 4.2GHz. The downlink transmitter provides additional amplification and sends the signal to the receiving earth stations. 46 Electronic Servicing & Technology August 1986, rectly designated as an effective temperature rather than a physical temperature because it includes both thermal and non -thermal Walk "tough dog" troubles out of any TV & VCR in half the time ... or your money back noise. The most popular LNAs, LNBs or LNCs have a 100°K rating. They are the best compromise between performance and cost. Also available are 85K and 120K units. The former is more costly but may suffice where dish size is an important limitation. The latter is less costly, but often requires a larger antenna. Low -noise block (LNB) down - converters are broadband devices that amplify all the signals from a given bird. They do not require tuning. LNBs are used singly or in pairs (duals). When using a block downconverter, signals from the even and odd (i.e. horizontal and vertical) transponders can be received individually (i.e. one at a time) or simultaneously, depending on the type of feedhorn assembly being used. If the feedhorn assembly has two orthogonal probes each feeding a separate LNB, then the LNB outputs can be delivered to a receiver with dual inputs. This permits all the transponder programs to be viewed simultaneously using separate receivers. Currently, many feedhorns use one probe, which must be rotated 90° whenever switching from even to odd (or vice-versa) transponders. This means that the cable that is carrying signals to receivers will contain only even or odd transponder signals at any given time. So, the advantage of dual probes and dual block downconverters allows you to view all programs on a given satellite simultaneously plus it eliminates moving parts in the feedhorn. That way, dad can watch football while mom and the kids watch the National Geographic Society special in another room. Antennas have been, and will continue to be, the most important link in the chain of satellite receiving equipment. Unless they perform well and achieve high efficiency, there is little anyone can do to improve or correct TV picture efficiencies further on in the chain. with the exclusive, patented, VA62 Universal Video Analyzer ...$3,295 Would you like to? Reduce analyzing time: Isolate any problem to one stage in any TV or VCR in minutes, without breaking a circuit connection, using the tried and proven signal substitution method of troubleshooting? Cut costly callbacks and increase customer referrals by completely performance testing TVs & VCRs before they leave your shop? Own the only analyzer that equips you to check all standard and cable channels with digital accuracy? Check complete, RF, IF, video and chroma response of any chassis in minutes without taking the back off the receiver or removing chassis plus set traps dynamically right on CRT too? Simplify alignment with exclusive multiburst pattern? Reduce costly inventory from stocking yokes, flybacks, and other coils and transformers, for substitution only, with the patented Ringing Test. Run dynamic proof positive test on any yoke, flyback, and inte- grated high voltage transformer ... in- or out -of-circuit? Protect your future by servicing VCRs for your customers before they go to your competition? Walk out "tough dog" troubles in any VCR chrominance or luminance circuit stage -by -stage to isolate problems in minutes? Have proof positive test of the video record/play heads before you replace the entire mechanism? Increase your business by meeting all TV and VCR manufacturers' requirements for profitable warranty service work with this one universally recommended analyzer? To prove it to yourself, CALL TODAY, WATS FREE, 1-800-843-3338, for a FREE Self Demo ... or learn how the VA62 works first by calling for your free simplified operation and application instruction guide, worth - - $10.00. Call Today Wats Free 1-800-843-3338 SNCOR 3200 Sencore Drive Sioux Falls, SD 57107 605-339-0100 In SD Only innovatively designed with your time in mind. Circle (17) on Reply Card August 1986 Electronic Servicing & Technology 47 Are you being chased by an overheated boomer Joseph J. Carr, CET Reliability experts measure Have you ever been cursed with a boomerang service job? These are equipment performance in terms fault symptoms that always seem of mean time between failure to come back. Some equipment (MTBF), which usually is exjust seems failure prone. When pressed in hours. For example, an you are facing a boomerang, be MTBF of 1,000 hours implies that, sure to consider overheating as a for a large number of samples of possible cause. It is widely the equipment, the average will be recognized that heat is a great one failure per 1,000 hours of operation. One source claims that killer of electronic equipment. Many device ratings are based a 10 °C rise in operating temperaon maintaining certain operating ture will cut the MTBF almost in temperatures. One bargain pack half. How important is cooling in elecaudio power transistor, for example, offers a seemingly tremendous tronic equipment? Let's consider collector -power dissipation (which some examples. About 10 years is prominently advertised), but the ago I worked in a university power is only available at room hospital repairing patient monitortemperature (25 °C to 30 °C). At ing equipment. The slave EKG ostemperatures above 30 °C the tran- cilloscopes at the nurses' central sistor must be derated substantial- station were a reliability nightly. Almost anyplace that the tran- mare. About once a week, usually sistor is used inside a cabinet or at 3 a.m., the staff would call me to box, the temperature will exceed come repair one of the four scopes. Yet the same model scopes at bed30 °C. Similarly, RF power transistors side operated reliably. The probin CB and land mobile transmit- lem was overheating of the central ters die as often from overheating station scopes, which were mountas from that elusive gremlin ed inside a completely closed VSWR, but the problem is less desk/console. After cutting 10 well recognized. I know one case 1 -inch ventilation holes, and inwhere there were constant failures stalling a pair of 100-cfm whisper of the RF power transistors in a fans, the central station scopes trunk -mounted 100W VHF power became as reliable as the bedside amplifier. Technicians repaired scopes. A second example is a story of the rig several times before they drew the connection with heat. tragedy prevented. My first perThe trunk of a car during the sum- sonal computer was a Digital mer months sizzles while the Group Z80 -based machine with passenger compartment cools off 26K of static (2,102 chips) with air conditioning in only a few memory. In those days, my kilo minutes. Moving the amplifier buck bought (in kit form) a motherbehind the dashboard cured the board, three 8K memory boards, a CPU board, a 64 line TV/cassette problem. By 48 Electronic Servicing & Technology August 1986 interface board (with some static memory chips on board), and several input/output boards. All of those boards contained lots of TTL devices, and they generated a large amount of heat. The builder had to supply the cabinet, a ± 12 Vdc at lA dual -polarity power supply and a + 5Vdc at 10A regulated power supply. At first, all those cards and the two do power supplies were buttoned up inside an almost totally unvented aluminum cabinet. Needless to say, the temperature of the cabinet rose to egg -frying levels, and the HEP S-7000 power transistor used as the series -pass element in the voltage regulator operated hot enough to take off skin when touched. That computer would have been a reliability headache if the heat wasn't removed. I installed a pair of 40 to 50 cfm fans: a 3.5-inch unit blowing across the S-7000 heatsink and a 4.5-inch unit cooling the printed wiring board compartment. Avoiding heat -induced failures No one with any professional electronics experience will deny that heat is the great killer of electronic devices. Equipment that passes or delivers large amounts of either current or power must be kept cool for proper operation. The methods given in this article are simple and sufficient for most servicing applications. Although reliability engineers and the thermodynamicists will flinch at the lack of mathematical elegance, the methods are nonetheless effective. Two things a technician í shouldn't be without ... The Telephone #2. The NEW MCM Electronics Catalog Your telephone is a very important part of your business. It saves you time ... it helps you run your business smoothly and efficiently ... it's dependable and it's convenient. ... Like your telephone, the new MCM Catalog offers you many of the same advantages. There is only one simple rule: where there is excessive heat, remove it. What does excessive mean? If the equipment feels too hot to the touch, or has a history of unexplained failures and/or repairs, then it is probably running too hot. An engineer will have specifications to meet and calculations to make, but they are beyond the scope of this article. The empirical skin of the thumb rule, however, suffices for our needs. There are three basic tactics that can be used either singly or in combination: 1.) radiate more of the heat, 2.) improve natural ventilation, or 3.) add or increase forced-air cooling. Water cooling is not an issue for most readers even though some commercial broadcast transmitters and high -power industrial electronics devices use circulating water for cooling. (I once worked in a 10kW AM broadcasting station that used the waste heat from the transmitter's water radiator to heat the transmitter building.) With our wide selection of product lines, you'll save time looking for parts. Our fast, friendly and dependable service will help you operate smoothly, and you'll like our low prices. Convenient too! Our nationwide toll free numbers make us as close as that other important business tool your telephone! - Call today for your FREE copy of the latest MCM Catalog. No obligation to buy! Catalog #12 Now Available Call TOLL -FREE 1-800-543-4330 (In Ohio call 1-800-762-4315) (In Alaska or Hawaii 1-800-858-1849) MCM ELECTRONICS A PREMIER COMPANY 858 E. Congress Park Drive Centerville, OH 45459 Source No. ES&T 12 Circle (18) on Reply Card August 1986 Electronic Servicing & Technology 49 Protecting transistors & IC regulators Figure 1. A heat sink such as the top hat device shown here slips right over sistor, helps radiate heat away. a tran- Figure 2. Transistors such as these plastic encapsulated devices can be mounted to finned heat sinks. Be sure to use heat sink grease to improve thermal transfer and ighten mounting screws just enough to ensure good contact. Figure 3. A.) A finned heat sink such as this one has a large thermal mass to conduct heat away from the electronic device and fins to increase the rate of heat radiation. B.) If you add forced air cooling with fans, make sure that the direction of air flow is through the heat sink. 50 Electronic Servicing & Technology August 1986 On small equipment, it is not practical (or possible) to use forced air cooling, so you will have to provide heat sinking for the semiconductors. In fact, even most forced air cooled projects will need these metal radiators. Figure lA shows the metal TO -5 transistor package. Most of these transistors are mounted on printed wiring boards, and are low -signal (and low -heat) devices. But certain TO -5 transistors, such as the 2N3053 and certain 3W to 10W RF power transistors, operate at moderate power levels (in audio drivers, for example). A top -hat finned heat sink such as shown in Figure lB is mounted on the TO -5 package to radiate heat. There are also certain other spring clip versions of this same kind of heat sink. Figure 2A shows two forms of plastic power device package. You will find these packages in audio power transistors (e.g. 2N5249), thyristors and 3 -terminal IC voltage regulators. In the regulator case, the devices are usually rated at 750mA in free air and 1,000mA when heat sinked. Either vertical or horizontal finned sheet metal heat sinks such as Figure 2B are used to provide heat dissipation. Be sure to use a thin layer of silicone heat transfer grease between the metal tab surface on the transistor (or regulator) and the heat sink. Also be sure to tighten the mounting screw properly in order to facilitate heat transfer to the heat sink. One of my boomerangs from my consumer electronics days was a low-cost stereo compact that used unheat- sinked, TO -220 transistors in the AF power amplifiers. We rarely got one of those monsters out of warranty before another failure occurred - that is, until we gratuitously added heat sinks to the transistors. Sheet metal heat sinks are suitable for TO -3 transistors and 3 -terminal regulators that are mounted on a PWB. The bent sheet metal heat sinks are good for up to about 10W of power, or Figure 4. Rectifier diodes and high power resistors should be mounted far enough above the circuit board so that the heat they generate does not damage the board. Large components may have to be supported with a heat -resistant spacer, as shown, lower right. voltage regulators up to 1.5A. For the 3A, 5A and l0A voltage regulators that also use a TO -3 package, it would be better to use a larger finned heat sink. In many units, the metal chassis is used for heat sinking. In those cases, the transistors are bolted either directly to the metal chassis or mounted via mica insulators. In both cases, silicone heat transfer grease is used between the semiconductor device and the chassis. This method is especially successful when the chassis is large, or when it is particularly thick (i.e. has a high thermal mass). Some printed wiring boards use large areas of unetched copper foil and/or large metal ridges or blocks to provide better heat sinking. This method is used especially where there are not single devices that can be individually heat sinked (e.g. a TO -220 transistor), but rather when there are a large number of heat -producing devices (such as TTL ICs). There are many different forms of large, finned heat sinks used for TO -3 (and other) transistors, high current voltage regulators and high -current diodes and SCRs; Figure 3A shows a side view of one of these heat sinks. In this case, the TO -3 transistor (or other device) is mounted on the flat central surface of the heat sink with screws. In most situations, it is wise to use a thin smear of silicone heat transfer grease between the device and the heat sink. This grease is especially needed when a mica insulator is placed between the semiconductor device and the heat sink. Again, it is necessary to make sure that the mounting screws are cinched down tight enough to allow maximum heat transfer (but not enough to distort the device package). 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Latest 260® Series $119 7 "Instant" null, peak, trend and continuity indications High immunity to transients, RF interference dB measurement capability at no extra cost Resistance indication from zero to infinity Self -powered voltage, current and dB ranges-no batteries to fail Reliable, accurate performance even under extreme environments Easy, low-cost maintenance-no expensive "chips" to fail UL Listed per U L-1244 Standard for Safety-Electrical and Electronic Measuring and Testing Instruments Complete line of UL recognized accessories Options include mirrored scale, extra overload protections, roll top carrying case See the World Famous 260 Series 7, the 260.6XL, the 270 and the Pocket -Size 160® at Leading Electronics/Electrical Distributors SIMPSON ELECTRIC COMPANY ,:en Lti 111151RUME1M INAI STAY ACCURATE 1 853 Dundee Avenue, Elgin, IL 60120 (312) 697-2260 Telex 72-2416 Cable SIMELCO Canada: Bach -Simpson Ltd., London, Ontario England: Bach -Simpson (U.K.) Ltd., Wadebridge, Cornwall Circle (19) on Reply Card August 1986 Electronic Servicing & Technology 51 (TOP VIEW) PRINTED WIRING BOARDS PWBs WRONG WRONG MOTHERBOARD WITH SOCKETS MOTHERBOARD AA A RIGHT CALL TOLL FREE Figure 5. When you add forced -air cooling to a unit that consists of a motherboard with other circuit boards plugged in, be sure that the air flow is in a direction such that it flows through the plugged in boards. 800-824-2873 Include work address and phone number for Free Catalog. Hitachi FLUKE FLUKE HITACHI Denshi America,Ltd. D Autorange Touchhold function SCOPES IWATSU All 20 models in stock 2-3 year warranties 2-3 year warranties MODEL PRICE 73 $ 79 75 1050 21 $ 99 23 509 $1299 $1199 VC 6041 $4400 20-250 MHz MODEL PRICE 5702 $ 535 5705 $ 899 422 1100 $ 690 $1900 $ 725 FLUKE 77 SALE 1070 $1595 $1695 1100A 7506 $ 749 V222 $2490 $ 550 LIST '715°° DIGITAL MULTIMETERS BECKMAN Berkman Industrial" D All 300, HD, and Circuitmate series All accessories in stock $ 99 $145 $259 8012A $359 8022B $154 8050A $389 27 $114 LIST $139°° Analog/Digital Multimeter POWER SOURCES POWER DESIGNS D Low and high voltage power sources 1-5 year warranties PRICE HD100 $169 HD110 $189 MODEL PRICE HD130 2020B $750 HD140 $239 $259 2K20 $695 300 $120 4050 $660 310 $145 6150 $725 320 $179 TW5005W $595 330 $219 TW6050A $880 350 $229 TW347 $695 360 $289 TP340 $750 4410 $239 TP343A $795 3-Way Power Supply USED TEST EQUIPMENT, TOO!-OVER 3,000 MODELS AVAILABLE AT HUGE DISCOUNTS WITH WARRANTIES! Quantity Discounts Available Dealers Welcome III Freight and Tax Extra States I IL United Instrument Rentals, Circle (20) on Reply Card 52 Electronic Servicing & Technology Immediate Availability of Equipment A U.S. Leasing Company Inc. August 1986 When forced air is used to cool a heat sink -a good idea when the power and/or current is high - then the orientation of the heat sink with respect to the airflow is sometimes important. Figure 3B shows the right and wrong ways to force air over the finned surfaces. Keep in mind, however, that orientation is not always critical, especially when air from the wrong direction is sufficient or blows over the entire surface. The designations right and wrong are merely general considerations for some critical applications. MODEL D DC -20 MHz Lightweight High Sensitivity and Fast Sweep Timer 8020B $199 80248 $249 $ 930 $1245 SALE $535 $229 8010A $279 650 5711 Portable Dual Trace Scope 25 V209 5710 HITACHI V-222 0.3% accuracy Analog display Heavy duty MODEL PRICE MODEL PRICE 20-100 MHz All 14 models in stock e 2988 Campus Drive San Mateo, CA 94403 Other components Certain components other than power transistors generate heat. Rectifier diodes and power resistors should be mounted with their bodies 0.125 inch to 0.250 inch off the PWB (see Figure 4). This procedure allows the heat to dissipate into the air instead of the PWB material. I have seen many phenolic and some fiber glass printer wiring boards badly damaged from the effects of a 10W power resistor mounted flush to the surface. Some "bargain basement" rectifier diodes can meet their rated forward current only when the rectifier is mounted 0.050 inch off the board and the axial leads are cut to 0.75 inch or Figure 6. Another way to provide for forced -air cooling is to direct the air flow through holes in the motherboard as shown in the drawing at right. longer. Those diodes are overrated and either should be used only in lower current applications or shunned entirely. Besides reducing the operating life or limiting the power output of circuits, overheating also can decrease performance in other ways. Certain circuits, oscillators for example, are inherently sensitive to heat. There was once a popular 2 -way radio transciever that suf- fered terrible frequency drift because the master oscillator was located next to the RF/IF strip vacuum tubes. Although that was such a bad design error that nothing would really repair the situation, a lot of people markedly improved the frequency stability by adding some Teflon thermal insulating material between the RF/IF PWB and the aluminum oscillator shielded housing. Large multiboard equipment When I first felt the temperature of my Digital Group computer cabinet, I took steps to get rid of the heat, and reliability was improved. Rarely does the homebrew builder have the flexibility that I had with my Vector Electronics S-100 cabinet. In most cases, the builder must do with only a single fan and must be clever to make best use of it. Figure 5A shows a typical large-scale multiboard project-such as a microcomputer or transceiver-in which plug-in printed wiring boards are installed on a socketed motherboard. Usually, these PWBs will be mounted in a closed cabinet for both EMI and aesthetic reasons. If we apply air broadside to PWBs, then only the first one in the line-up will benefit. Figure 5B shows a top view that permits you to see right and wrong airflow directions. Obviously, air coming in from the sides is able to remove heat from more of the PWBs more effectively. Figure 6 shows a method used in a 6502 -based microcomputer. The PTS SLASHES MODULE PRICES UP TO 40%! Your new PTS Product Guide has great news. PTS popular modules by 10 to 40%! Choose quality PTS replacement parts. You get automatic updates, full year limited warranty, and instock availability or fast 8 -hour turnaround of all makes/ all models. Plus you get real savings. More professionals choose PTS rebuilt modules than any other. Put PTS to work for you. is cutting prices on PTS Corporation The world's largest independent electronics rebuilder. Send for your free Product Guide today! PIS Corporation 272 P.O. Box ton, IN 47402 Blooming (812) 824-9331 REPAIR RCA MODULE 1517.....MAG001 " B Q 3`¡ ' RCA MODULE MCH001B B MAE001 . MAH001B 12.4eMDR001 3S 15; A MpG001 A MAH004G MCH002B 11140 ( Ii% W II. 1 $ç A MDD001 MpC001 A M AD001 . r1106.. 5 9Il0 REPAIR PRICE . . . . MDS001B MAC002B . . MDS001A.. MCS001 A . . . . . . . . . 1Qj¡ ,xr MAP ..>-3e14.9) 'OOC Z. 'r30 . MDL002A.' MCL002A i3q MAG004A Mp,A001A.... .ecT007 ... 30.50 Circle (21) on Reply Card August 1986 Electronic Servicing & Technology 53 builder used a large metal chassis with a motherboard mounted on it to hold the PWBs. There were 0.75 -inch holes cut in both the chassis top and the motherboard to admit air between the boards. Although only one hole is shown between each board in this side view, there were four per row in the actual computer. Air from the blower flowed up through the holes and across the electronics components on the PWBs. Radio -frequency power amplifiers and high -power transmitters pose special heat problems. Some linears, for example, are only 45% efficient. Therefore, a 1,000W linear amplifier delivers 450W of usable RF power and 550W of waste heat. To make matters even worse, the necessity of keeping harmonics at home means we button up all that heat in a shielded metal cabinet. Most RF power amplifier tubes used in medical diathermy and electrosurgery equipment, industrial inductive heaters and radio transmitters must be forced air cooled in order to realize their full ratings (some are absolutely dependent on cooling). Figure 7 shows two methods for providing the needed cooling air. In Figure 7A, the blower is mounted so that the air flow is directly over the glass envelope. The fan may be mounted either exterior to the RF compartment (as shown) or inside. The other method, shown in Figure 7B, assumes the use of air system tube sockets. A blower or fan supplies air to the bottom side of the socket, and the air is directed upward through holes in the socket and around the glass envelope. A chimney aids in keeping the airflow against the glass. Some air system sockets have plumbing connections for the air hose, while others depend on pressurization of the lower compartment. In either case the reason this socket is better is that the pin seals with the glass are kept cooler. The plate cap pin seal should also be kept cool, if possible. Toward this end some builders use a finned heat dissipating plate cap to make electrical connection to the anode. Figure 7. A.) If the unit to be cooled must be shielded from RFI, the cooling air may be ducted through a screen shield. GLASS AIR CHIMNEY AIR -SYSTEM SOCKET the manufacturer, there are Air system tube sockets direct the cooling air to ensure that it flows past the component that needs cooling. B.) 54 Electronic Servicing Modify when you can Heat is the great destroyer of electronic components. If a piece of equipment runs too hot, then the result will be flaky operation, frequent breakdowns and all the headaches that accompany low reliability. Although it is ordinarily unwise for professional servicers to modify equipment without expressly written instructions from & Technology August 1986 sometimes exceptions to this rule. An obviously overheating piece of equipment that can be modified with no adverse effects is a candidate for exception to the rule. The simple methods shown in this article will permit you to modify equipment to gain the longest and most reliable use possible for yourself, your customer or your employer. These Photofact folders for TV receivers and other equipment have been released by Howard W. Sams & Co. since the last report in ES&T. PANASONIC CTF-2501 /02/09, CTG -2501 /02, PC -26L01/02/09 ..2422-3 RCA Chassis CTC125E EMERSON ECR-135 2418-1 HITACHI CT -1957, CT1957B 2419-1 HITACHI CT 1958 2420-1 2419-2 RCA Chassis CTC120C 2423-2 SEARS 564.48700550 2420-2 SONY Chassis SCC-548N-A/O-A, SCC-552K-A HITACHI CT2647, CT2648, CT2649 2421-1 HITACHI CT19B3, CT19B5, CT1953, CT1956 . 2423-1 2424-1 MAGNAVOX Chassis 25C508,09/11/15/16/17/22/23/31/47/48/49/53/54/ 2418-2 63/64/65 MGA/MITSUBISHI CS -1904, CS -1905 SONY Chassis SCC-548V-A, SCC-552L-A, SCC-648D-A 2424-2 HITACHI CT1951 2421-2 2422-2 MONITOR APPLE Monitor II A2M2010 2422-1 OKIDATA Microline 92 CP20 RADIO SHACK MODEL 4 (Gate Array Version) CSCS13 asY Plug in! To the NESDA Syse111. YOUR BUSINESS is in the world's fastest changing industry. If you're not careful, you could find your business in the dark. But, you don't have to stay there. Through a system of local, state, and regional groups, the National Electronics Sales & Service Dealers Assn. (NESDA) keeps members up-to-date with the fast pace of advancing technology while offering: Managerial and technical training. Business contacts. Technical and management Don't be certification. Information on new products. Legislative activities that affect the industry. left in the dark. Let the NESDA system work FOR YOU! For more information and an application, write to. NESDA, 2708 W. Berry St., Ft. Worth, TX 76109; Ph (817) 921-9061 Name ONNECTING GABLES Sh/TCyFS '91-.4>s, EDGE CONNECTORS PLUGS Zip Member of State O. Local O Asen Phone STRIPS GOLD PLATED CONNECTORS & BATTERY CoNTAC POTEt'leAETERS CRAMOLIN' Even the finest equipment in the world cannot guarantee noise -free operation. One "dirty" connection anywhere in the electrical path can cause unwanted noise or signal loss. "MORE THAN .4 CONTACT CLEANER" CRAMOLIN® is a fast-avting, anti -oxidizing lubricant that cleans and preserves all metal surfaces, ltcluding gold. When applied to metal contact; and connectors, CRAMOLIN5' removes resistive oxides as it forms a prdective molecular layer that adheres to the metal surfaces and maintains maximum electrical conductivity. CRAMOLIN5 Address TERMINAL SOCKETS Bell & Howell Captol Records Dolby Laboratories Bus. Name State CONNECTION PROTECTION - USED BY THOSE WHO DEMAND THE BEST: Hewlett Packard John Flake Mfg. Mclnio-1 Labs MCI(Sony) Motorola NASA Nakamichi RCA Switchcraf-, SINCE 1956 CAIG or3=_*) ;fAl tiC*) ;etDE=1/1 1175-0 Industrial Ave.. (P.O. Boa )1) - Escondido, CA 92025-0051 U.S.A. (619) 743-7143 Circle (22) on Reply Card August 1986 Electronic Servicing & Technology 55 By Sam Wilson In a recent article we illustrated the difference between a time domain and frequency domain display. The illustration (Figure 1) is repeated here to show the difference between those displays. In this article we will discuss some tests based upon a frequency domain display. As you know, an oscilloscope can be set up to show a frequency domain display. However, there is a test instrument, called a spectrum analyzer, that is especially designed for this. If you do much quality audio work, you will find this a very useful instrument. Review of terms Bandwidth-The range of frequencies between the points on a frequency response curve where the voltage amplitude drops to 70.7% of the maximum value. This assumes that the input amplitude is cons- tant for all What do you knowabout electronics ? Tests for low-frequency amplifiers measurement of the collector voltage of a transistor. A value of 10V would be a quantitative result. A qualitative test requires the technician to make an evaluation based upon some evidence that is not a numerical value. A good example of a qualitative test is using an oscilloscope to examine a waveform at some point in a circuit. frequencies. Rise Time and Decay Time-With an input step voltage the rise time and the decay time are both equal to the time between 10% and 90% of the output voltage range. Some thoughts on testing One of the accepted procedures for troubleshooting is based upon measurements. The procedure is to make a measurement at some point in the faulty circuit, and if the result of the measurement is what you expect to get at that point, you know you are not at the source of the trouble. So, you move to the next logical point, make another measurement, and evaluate the result. You continue to do that until you come to a point where the test result is not correct for that point. In that case, you have most probably located the site of the trouble. A key to successful troubleshooting by this method is to make accurate tests. Qualitative and quantitative tests For troubleshooting purposes, technicians make two types of tests. A quantitative test gives numerical values as evidence that a circuit is or is not working properly at some point. An example is 56 Electronic Servicing & Technology August 1986 SQUARE WAVE FISC OR FUNCTION GENERATOR o SCOPE AMPLIFIER Figure UNDER TEST 2. OUTPUT OF AMPLIFIER WITH POOR HIGH FREQUENCY RESPONSE OUTPUT OF IDEAL AMPLIFIER 7,ltiv pr it" OUTPUT WHEN AMPLIFIER HAS EXCESSIVE HIGH FREQUENCY RESPONSE Figure 3. OUTPUT WHEN AMPLIFIER HAS POOR LOW -FREQUENCY RESPONSE The technician makes a decision as to whether or not the waveform is sufficiently close to the ex- pected result. Very often the expected result is provided by the manufacturer of the equipment. FUNCTION GENERATOR o The square wave test Square wave analysis of /AMPLIFIER UNDER TEST Q amplifier performance is a good example of a qualitative test. As shown in Figure 2, a square wave is delivered to the amplifier input. The output waveshape on the oscilloscope is evaluated by the technician. Anything other than a square wave at the output indicates that the amplifier has in FIRST, MEASURE THE RISE TIME WITHOUT THE AMPLIFIER. CALL THIS VALUE B. (USE SWEEP EXPANDER ON SCOPE TO GET ACCURATE MEASURE OF RISE TIME.) some AMPLIFIER UNDER TEST NEXT, PUT THE AMPLIFIER IN AND MEASURE THE RISE TIME AGAIN. CALL THIS VALUE A. THE RISE TIME DUE TO THE AMPLIFIER IS APPROXIMATELY EQUAL TO A MINUS B. FIGURE 4. NESDA Computer Group COMPUTER SALES AND SERVICE DEALERS WORKING TOGETHER Service training. Assistance in selecting in-house .II equipment and software. 74;11 i.,l°" .4.!yi(3f. ei241i/e.;,/l:il,LiAT ri Specialized software for service management. TRIPLERS/MULTIPLIERS HIGH VOLTAGE REPLACEMENT FOR ECG°/GE°/SK° 8.75 8.85 8.85 10.70 9.99 500A/0E527 & SK3304 523/0E528 & SK33o6 526A/s1mD6 528/90906 529/GE529 & SK3307 165/510115 238/0E37 & 283/x&3467 & GE38... sK3710 2.25 ... 2.25 2 75 2 25 2 25 2SD1341P FOR MORE INFORMATION SEND BUSINESS CARD TO: MIN. 2SC1172B 5 MIN. 1.95 1.95 2.35 1.95 1.95 1.75 1.75 1.80 1.75 1.55 50 MIN. 100 MIN. AUDIO POWER 10 50 100 10 min min min TYPE 152/51(3893 153/5x3274 125 156 506 Factory contacts for service literature and parts. NESDA COMPUTER GROUP, 2708 WEST BERRY STREET FORT WORTH, TEXAS 76109; PHONE (817) 921-9061 3 6.95 7.20 7.20 8.70 7.95 100 MIN OUTPUT TRANSISTORS 50 100 min min min TYPE .30.25.21 .30.25.21 196/SK3054 197/5x3083 10 1000v/2.5Á 1000V/5A DAMPER/HI-VOLT-FAST RECOVERY 100 500 7C 6C 1Y ,E 10 102A 123A 123AP ... 129 130 159 162 163A .35 .18 .13 .38 .59 .16 2.25 2.35 min 100 min .32 .16 .11 .35 55 .13 1.95 1.99 TYPE .29 .14 .09 10 184 185 198 199 234 375 .29 .11 1.49 1.55 5C 13e 24C ADDITIONAL SAVINGS 50 100 1000 16e 18e 29 $$ min 50 min min min TYPE .49.44.39 291/51(3440 .49.44.39 .59.54.49 292/93441 .49.45.40 RECTIFIER DIODES Involvement in a stable and productive national trade association. the modified way waveshape. Some examples are given in Figure 3. By interpreting the output waveshape, the technician makes a qualitative judgement about the bandwidth of the amplifier. There have been a number of attempts to make the square wave test quantitative. For example, you may have heard that you can multiply the square wave frequen- min .38 .38 .60 .18 .19 .44 50 19CC SS min 100 min .33 .33 .54 .15 .16 .42 .28 .28 .49 .12 .13 .60 FOR A COMPLETE LIST CALL OR WRITE-C.O.D. Orders Welcome (Mln. Order $25) DIGITRON ELECTRONICS 110 HILLSIDE AVENUE, SPRINGFIELD, NEW JERSEY 07081 Toll Free 1.800-526.4928 In NJ 201-379.9016 Telex 138441 PRICES SUBJECT TO CHANGE WITHOUT NOTICE. OFFER GOOD WHILE SUPPLY LASTS. is a Trade Mark of Philips ECG, Dlgitron Ele. not associated with Philips ECG. EC. Circle (23) on Reply Card August 1986 Electronic Servicing & Technology 57 cy by 5 to determine the bandwidth of the amplifier. According to this rule, if the amplifier can pass a 5,000Hz square wave (without modifying it), it has a bandwidth of at least 5 x 5,000, or 25,000Hz. That rule is easy to use. Unfortunately, it isn't valid. You cannot accurately determine the frequency response of an amplifier with a square wave test. The square wave test should be used as a quick qualitative evaluation of amplifier A4 Figure illustrated in Figure 5. In (a) of this illustration, you can 58 Electronic Servicing & Technology C-FUNDAMENTAL PLUS 3RD AND 5TH HARMONIC D- FUNDAMENTAL killi 5 A. ...4...e....w. 7 9 I i I 11 13 15 , 17 v HARMONIC Figure 5 B. SAWTOOTH 0.35 rise time An alternative quick test The square wave test is based upon the fact that a square wave can be considered to be made up of a fundamental sine wave and a large number of odd harmonics. This makeup of the square wave is FUNDAMENTAL -FUNDAMENTAL PLUS 3RD HARMONIC TIME I That equation gives a reasonably accurate approximation of bandwidth provided certain precautions are observed. An important step is to determine how much of the square wave leading -edge rise time is due to the amplifier itself. The oscilloscope amplifiers and the square wave being used for the test also will have a certain amount of rise time that must be taken into consideration. Figure 4 shows how the test is performed. The rise time of the signal at the input to the amplifier is first measured. This must be done with the amplifier attached. Then, the rise time of the output signal is measured. The values are subtracted to determine how much of the rise time is due to the amplifier. This value is plugged into the equation. If you were careful with your measurements you have a good idea of the bandwidth. 4 B INFINITE NUMBER OF ODD HARMONICS 5 Bandwidth = D ' bandwidth. The bandwidth/rise time square wave test There is one quantitative evaluation that can be made using the square wave test of Figure 2. It is based upon an empirical equation. (An empirical equation is based upon experience rather than upon a mathematical procedure.) Here is the equation: B 3 Figure 6. IIIIi,i 5 7 9 11 13 TIME DOMAIN 15 17 v HARMONIC see how each additional odd har- every harmonic, both even and monic frequency brings the odd, is present. This gives a better waveform closer and closer to a view of the amplifier linearity square waveform. because some amplifiers eliminate In (b) of the illustration, you can only the even harmonics. Those see the harmonic content of the would not show distortion when square wave on a frequency do- you conduct a square wave test. Another advantage of using the main display. Note that the amplitude of each harmonic must sawtooth waveform is that be reduced for a true square amplifier clipping will show in the test. Clipping cuts off the top waveform. In theory, it would take an in- and/or bottom of the square wave, finite number of harmonics to pro- but you cannot see any effect. The duce a perfect square wave. In sawtooth waveform gives a steep practice, if the first 10 harmonics decay time that can be used in the are present, the waveform is quite rise time/bandwidth equation given earlier. In fact, despite its satisfactory. The very low amplitude of the popularity there doesn't seem to be upper harmonics accounts for the any good reason for the use of fact that the square wave test does square waves instead of sawtooth not give a true picture of band- waves. Having presented the case for width. Their amplitude is not sufficient to extend into the non-linear the sawtooth waveform test, the portion of the amplifier next question is: Why is it seldom characteristic, so no modulation used? Technician readers will have to send me the answer to that one. can take place. Compare the harmonic content I don't know. If you write to me concerning an of the square wave with the harmonic content of a sawtooth wave article in Electronic Servicing & as shown in Figure 6. Note that Technology, the editor considers August 1986 controlled oscillator). The VCO frequency output is used to sweep the scope trace back and forth as the generator frequency is swept up and down. The result is a frequency domain display similar to one shown in Figure 7. You easily can see the response F of the amplifier with this setup, but it is difficult to determine the BANDWIDTH exact frequency where the output is down to 70.7%. Figure 7. It helps to mark the trace with that you have implied your permis- an accurate signal generator sion to publish your letter, or ex- signal. An audio generator works cerpts from it, either in this very well for this purpose. This department or in the "Feedback" marker can be delivered to the Z department. (We may have to edit axis to intensity modulate the your material.) trace. The result is a bright spot on If you write a letter to me in care the curve to mark the audio freof Electronic Servicing & quency. (Important: Keep the Technology and you do not want it marker amplitude as low as possito be published in ES&T in any ble to prevent mixing of the form, you must so indicate. signals inside the CRT.) By adjusting the audio generator Using the function generator frequency you can move the Most function generators can be marker to the high -frequency used as sweep generators. The point, where the response is down oscillator that sweeps the to the 70.7% mark. The audio generator frequency is usually generator setting tells you the upreferred to as the VCO (voltage per limit of the bandwidth. MAXIMUM VALUE ! You must repeat the procedure to find the lower limit of the bandwidth. If the amplifier under test is do coupled, the response will fall to 0Hz, making it unnecessary to measure the low end of the bandwidth. With the tests described in this article it is possible to check quickly the frequency response of an amplifier. These tests are useful for troubleshooting an amplifier that performed well in the past but is now giving unsatisfactory performance. In the next issue I will review another quick test, then show some more advanced tests that give a better evaluation of an amplifier's capability. Your letters are very important to me. Write to me at the following address: Sam Wilson c/o Electronic Servicing & Technology P.O. Box 12901 Overland Park, KS 66212-9981 GSM, COMPLEX ATTENTION Technicians, Get Serious IMPEDANCE TECHNICIANS About Your * * Profession Being a certified electronics technician lets people know that you are a professional in your field. It tells them that you are serious about your work and can perform up to CET standards. * * * * Now you can order the "Study Guide for the Associate -Level CET Test" from the International Society of Certified Electronics Technicians. It includes neterial covering the most often rrissed questions on the Associate CET Exam 8i4" x 11", paperback, 60 pages. For More Information Contact: ISCET 2708 W. Berry, Ft. Worth, TX 76109. (817) 921 9101 NAME ANALYZER JOB OPENINGS MONTHLY TECHNICAL TRAINING PROGRAM BUSINESS MANAGEMENT TRAINING LOW COST INSURANCE CERTIFICATION TECHNICAL SEMINARS All of this in a nonprofit * Speeds international association for technicians * Variable CITY copies @ $5 (+ $1 postage.) Quickly - FIND OUT MORE: e i/I "` ((ETA. If you have always wanted a REAL component analyzer, but didn't want to shell out 1000's of S, Order Your CIA Todayl 819800 PPD to USA address SYNCHRONICITY RESEARCH CO. STATE ZIP - * Wide Z Range CMOS Safe *Works IN or OUT of Circuit * Use With Any X -Y Scope `110 ed./ ADDRESS Up Field Service Freq & Drive *Tests Any Part 604 N. Jackson St. Greencastle, IN 46135 P.O. Box 153 405-628-3695 TONKAWA, OK 74653 send material about ISCET and becoming certified. Circle (24) on Reply Card August 1986 Electronic Servicing & Technology 59 powered for absolute line isolation and features high stability and accuracy with a total of 58 discrete frequencies between 4MHz and 0.008Hz is now available from Technical Novations. Circle (79)on Reply Card Component analyzer Synchronicity Research has developed the Complex Impedance Analyzer. The CIA uses your scope to display the E -I signature of the component under test. Although Multimeters and accessories A line of ECG multimeters, an oscilloscope probe and accessories are now available from Philips ECG, a division of Amperex Electronic, a North American Philips company. The multimeters are models DM -300, DM-25, FET-43, DM-310 and model DM -74. The complete wire stripper/cutter; needle -nose pliers; miniature diagonal cutter, and more. Designated the model 130, it provides both decade and binary division of its basic high stability, temperature compensated 4Mhz crystal oscillator. Provisions are included to use an external crystal or use the decade/binary dividers only with an external signal input. Circle (77) on Reply Card line consists of four digital multimeters, an analog meter, an oscilloscope probe and various accessories. Circle (75) on Reply Card Technical service data Howard W. Sams & Co., a division of Macmillan, has introduced new "Computerfacts" technical service data for eight Commodore products, in addition to Computerfacts manuals for more than 70 other microcomputers, printers, disk drives, systems and monitors. Computerfacts follow one standard format, regardless of the manufacturer. Each manual contains standard -notation schematics created by a computer -aided design (CAD) system, reproductions of actual waveform photos taken from test equipment, TV stereo synthesizer The Televonics Sound Systems' model 2001 is a TV stereo synthesizer that is installed directly into any TV set to provide the listener with full -spectrum sound with no cutoff of high frequencies. Breaking the audio spectrum into distinct frequency bands enhances the stereo effect of the synthesized sound by adding directivity. A theater-hall effect results when proprietary phasing circuitry adds the necessary depth at precise frequencies. Circle (78) on Reply Card Printed circuit board repair kit Jensen Tools has introduced a compact kit of essential tools for circuit board technicians. Recommended for in -the-field CB troubleshooting and repair, this versatile kit in a roll pouch contains: a cordless mini -drill with half-moon bit for fine circuit board drilling; miniature 12W soldering iron; a pocket pack of 60/40 solder; two soldering aid tools; spring- preliminary service checks, troubleshooting tips, replacement parts lists and semiconductor cross-references. Circle (76) on Reply Card Precision frequency source A low-cost, portable precision frequency source that is battery 60 Electronic Servicing & Technology loaded piston -type solder remover; DIP insertion and extraction tools; August 1986 ¿. ti/ke and components not included . -.. all other component analyzers use a sine wave test signal, the CIA uses a triangle wave test signal of variable frequency (to 10kHz) and variable amplitude (to 30Vp-p). In addition to improved semiconductor tests, the triangle wave and wide frequency range make possible accurate inductance and capacitance tests over a wide range of values (from under 10pF to over 20µF and under 2mHz to over 200Hz). The impedance of complex networks (such as amplifier inputs and power supplies) and transducers (such as mics and speakers) can be measured. Circle (80) on Reply Card Shaft cutter The model 85 shaft cutter, from Turnex International, is designed for use in production, prototyping, and maintenance of electronic devices. It is easy to use, says the company, and the cutting is done in a second. It will cut all shaft materials including stainless steel and most plastics. This guillotine -type tool is made of high quality steel that is hardened to 62 HRC hardness. All parts subject to wear are bonderized to minimize friction. The tool has seven holes for cutting of all standard -shaft diameters. Circle (81) on Reply Card VCR REPAIR MADE EASY Sams is your source for reliable, state-of-the-art service data for major VCR brands. The Sams PHOTOFACT® standard notation format, your tool for 40 years for television and computer repairs, is now being applied to VCR servicing. Technicians! VCR schematics, troubleshooting data, and parts listings keep you from having to adapt to different schematic styles and layouts each time you service equipment from a different manufac- turer. Become familiar with all the brand -name equipment, delete the guesswork in troubleshooting, and build customer loyalty fast from quality service in this rapidly growing market for VCR repair. depend on the reliability of Sams VCR Technical Service Data. The service data is created in our own labs by Sams engineers. Every board, component location, every grid and waveform is checked and re -checked. You can Faster Repairs. More Business. More Profit! Repair Made Easy .. . Color coding of test point locations/voltage measurements and GridTraceT" are exclusive methods of reading schematics and locating components with "road map" coordinates. Circuit boards are depicted in a component -side view. Easy -Read Waveforms - Clear reproductions show you exactly what your test waveform should look like. Replacement Parts Cross References - Give you choices for equivalent components without costly and time consuming trial and error. VCR manuals are approximately 80 pages, 8' x 11, and loose-leaf bound for easy use. Each manual covers one VCR model. Sams VCR Technical Service Data is available for $21.95 each from local electronics distributors, book stores, or from Sams. Ask for details on the "Bonus -Buy Plan" for volume discounts and for Standing Order information. TECHNICIANS! 6 valuable test instruments. Register to win one of Register to win FREE test equipment. Just complete the order form attached and mail to Sams or call 800-428 -SAMS or in Indiana, call 317-298-5566. Ask for Operator 880. GRAND PRIZE Name SENCORE Universal NTSC Video Analyzer Model VA62 B & K PRECISION-NTSC City TEGAM, INC.-Digital Multimeter-Model 130A 1251 SIMPSON-Digital Multimeter -Model FLUKE-Digital Multimeter -Model Your Title Address Other Prizes Signal Generator -Model Company State Zip Phone TRIPLETT-Digital Multimeter-Model 464 D-3 8060A SAMS 3360 Test equipment is supplied to Sams by each manufacturer. List the VCR brands you would like Sams to cover to be eligible to win valuable test equipment. Entries must be received by November Brand Mail to: Indianapolis, Howard W. Sains & Co. 4300 West 62nd Street Indianapolis, IN 46268 Division of Macmillan, Inc. 4300 West 62nd Brand Department DM Howard W. Sams & Co. A Model 1. Model Or Call 800-428 -SAMS Ask for Operator 841 Street IN 46268 Circle (26) on Reply Card August 1986 Electronic Servicing & Technology 61 Answers to the Readers' Exchange Quiz WITH SWEEP EXPANDER Wanted: SG165 stereo analyzer, will pay as much as $400, you ship; late model Heathkit CRT tester, will pay as much as $50, you ship; for VCR repairs -tape tension, spindle gauge, VCR manuals. Michael P. Mena. P.O. Box 1479, APO New York, NY 09193. Wanted: Service manuals for Topaz Anti-Brownout ac Line Regulator, model 2LRA117SN; Motorola/McGraw Edison RF signal generator, model XT1034C/T1034C; Plessey Tellurometer, model MRA 101; Motorola walkie talkie, model HT -200 lowband; Supercall mobile telephone, model 60 80 KM; CB radio, Claricon Raider model; J.I.L. model 615CB; RCA radio phone, model CRM-P3A-5 Mark VII and for numerous other items. Send s.a.s.e. for list. Réjean Mathieu. VE-2-EUI. 1897 3rd Ave.. Val d'Or, Quebec J9P 4N7 Canada. - Figure Figure 3. 1. For Sale: Sencore VA48, mint condition, all probes and manuals, $600; Tektronix 50MHz dual -trace D75 model, $400. Anthony Ruoppolo, 182 Kimberly Ave., East Haven, CT 06512; 203-469-2205, after 6 p.m. For Sale: Royal electric correctable typewriter, model SE5000, three type A.) elements and box of film ribbons. Used very little and in mint condition. Cost, new, over $1,000; an excellent buy for $395. Will ship UPS. Bob Goodman, P.O. Box 452, Alexandria, LA 71301; 318-640-1466. For Sale: B&K 415 sweep/marker generator, with cables and manual, excellent -plus condition, $350, or will trade for a Sencore SC61 in good condition, or other dual -trace, do to 50MHz scope. Paulmer L. Williams, 322 North Court St., Lewisburg, WV 24901; 204-647-5414. For Sale: Mercury all in -circuit capacitors tester, model 1400, with electric eye, in mint condition, $25 plus postage. Jos. A. Gontarz, JAG's Radio & TV, 14 Rudolph Road, Forestville, CT 06010; 203-583-7532. For Sale: Clough-Brengle model OC signal generator, 65kHz to 30MHz, six bands, modulated or unmodulated, 400Hz audio output jack, factory hand -calibrated, $35; Dumont No. 164E 3 -inch oscilloscope, $35; EICO model 221 VTVM, factory wired, $35; TOBE condenser analyzer, $15. All in perfect condition, with manuals. All prices plus shipping. M. Seligsohn, 1455-55th St., Brooklyn, NY 11219. For Sale: Hickok model 610A alignment generator with manual, $45; Dumont battery -operated communications frequency meter, $25; 24 B&W 7 -inch video tapes, $20 for all; model 7 Webster -Chicago wire recorder, $20; Precision E -200-C signal generator with manual, $40. Add $5 for shipping. Clark Trissell, 3530 Pawnee, Lincoln, NE 68506; 402-488-5263. Wanted: Cartridge head shells (white) for Garrard A-2. For Sale: NOS (boxed) Collard RC -456 changers, $20; RCA WR502A (battery portable) WR502A chro-bar generator, matches WV -510 TVM, $25; 2 -tube UHF converters, $10 each. All working and prepaid. Jim Farago, P.O. Box 65701, St. Paul, MN 55165. Wanted: Service manuals or schematics, or both, for two R.J. MacDonald products: AM/FM radio/record player, model M-9040; portable stereo radio/cassette model code No. 06-33-67. I will gladly pay for original manuals or copies of same. J.L. Wingfield, P.O. Box 685, Cedaredge, CO 81413; 303-856-6341. Figure 2. SW B.) Figure 5. LLIAMMETER FUSE Wanted: Service information and/or schematic for Kenwood KR -4200 AM FM stereo receiver. Will copy and return, or will pay for copies. J.R. Janeczko, Accurate Electronic Service, 409 4th Ave., Haddon Height, NJ 08035. Wanted: Heath model IB-2A impedance bridge, in good condition, with manuals. Bob Kramer, 919 Grove St., Aurora, IL 60505; 312-898-8946. For Sale: New receiving tubes, all types but mostly RCA, in original cartons, 80% off list price. Send s.a.s.e. with wanted list. Shipping: 504 per tube. James Vandemark, Box 3472, Santa Rosa, CA. 95402. For Sale: World War II -era capacitors, tubes, etc., for sale, or will trade for panel meters, solid-state electronics books or back issues of magazines on electronics and photography. Ransom Beers, Box 758, Blythe, CA 92226. For Sale: Electronic Servicing & Technology magazines, September '76 to date; Popular Electronics, January '77 through October '82; schematics, Electronics Technician Dealer Tekfax, No. 1 September '52 through No. 1923 April '82; ES&T Profax, No. 2000 October '82 to date. James B. Geier, Jimco Services, Box 341, Ketchum, ID 83340. Wanted: Tektronix 321A or 321 oscilloscopes, any condition. Mary Loft- Wanted: Sams Photofact VCR series No. VCR67 (out of print). Will buy or copy Sylvania No. VC2210 chapter and return. Ed Duda TV and Repair. Linwood, NE 68036, 402-666-5842. For Sale: RCA VTVM, model WV -98A senior voltohmyst, $50. Barnes TV-Radio Service, 118 W. Main St., Camden, TN 38320; 901-584-6411. For Sale: Sams Photofact CB radio series-CB11, 12, 15, 16, 21, 22, 23, ness, 115 W. 20th Ave., Olympia, WA 98501; 205.357-8336. For Sale: Sencore SC61, $2,500; Sencore VA62, $300 and assume; several other pieces at reasonable prices. Sams Photofacts, RCA and Zenith tech data, RCA and Zenith parts at 25% of cost. Send s.a.s.e. for list. Jim Frost, Jim's TV Service, 95 S. Wintzell Ave., Bayou La Batre, AL 36509; 205-824-2262. 25, 34, 42, 46, 48, 49, 52, 54, 55, 63, 65, 109, 113, 115, 123, 129, 249. Wanted: Sams Photofact CB radio series-CB170, 172, 173, 175, 176, 177, 178, 180, 182, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 201, 202, 203, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 219, 222, 223, 224, 225, 227, 229, 230, 231, 232, 233, 234, 236, 239, 240, 241, 243, 244, 245, 246, 247, 248, 252 and up. Paul Garner, P.O. Box 636, Millbrook. AL 36054; 205-285-5839. Needed: Service information and schematics for the TOCOM converter/descrambler, model 5503. Will pay price for information that can be delivered. D.G. Seibel, 6201 35th St., Lubbock, TX 79407; 817-232.3838. For Sale: B&K 5-inch triggered scope, model 1461, $225; B&K color generator, model 124S (transistor) $59; B&K bench DMM, $79.50. All good Wanted: Panasonic color picture tube No. A-26JAS31X, Sams TSM service, B&K's CRT tester model 470 test adapter sockets CR12 to CR29. Ed Herbert, 410 N. 3rd, Minersville, PA 17954. condition. Old-time RCA voltohmyst, model WV -87-B, very big scale, $45. Prices plus shipping. Needed: Instructions and service information on Hickok Cardmatic tubetester, model 121. Will copy and return, or buy if reasonable. Maurer TV Sales & Service, 29 S. 4th St., Lebanon, PA 17042; 717-272-2481. 62 i Electronic Servicing & Technology August 1986 Wanted: Schematic for Panasonic model CT702 Quatre color, and for Texas Hitech model THT-606. Will purchase or copy and return. C. Bufano, 15 Green Hills Drive, Shelburne, VT 05482; 802-985-2419. For Sale: Diehl Mark V, new in box, $500; Diehl Mark III, new in box, $300. Dwight's Electronics, 9875 Piute Drive, Salida, CO. 81201; 303-539-7571. 1. B - At 400Hz the primary current is limited by the inductive reactance. (XL = 2irfL) Lowering the frequency reduces the inductive reactance. With less opposition to primary current, there will be a higher current and resulting heat. 2. B - The ability of a receiver to reject image frequencies is not related to oscillator stability. So, phase locking the oscillator will not have any effect. Choices A, C, and D are the methods usually used to improve image rejection. 3. C - (This is the definition of eutectic solder.) When solder is made of 63% tin and 37% lead, it is eutectic. For all other combinations of tin and lead, the solder passes through a plastic state between the solid and liquid states. A quick change from solid to liquid is desirable because heat is applied for less time. That is im- portant for preventing heat damage to components. 4. E - The waveform shown in Figure 1 represents excessive high -frequency response. The small enhanced areas following the leading edge represent oscillations that are characteristic of this type of amplifier. 5. D- The circuit is known as a clamp. It has also been called a baseline stabilizer, and a dc restorer. On one-half cycle, the capacitor charges through the diode as shown in Figure 2 (A). The output voltage is zero at this time. On the next half cycle, the capacitor voltage is in series with the generator voltage. The total output is their sum, or, + 10V. This is shown in Figure 2. (B). 6. The completed circuit is shown in Figure 3. Use the left-hand rule, which states: grasp the coil so that your fingers are pointing in the direction of electron flow. Then, your thumb points in the direction of the North Pole. The resulting north and south poles are shown in Figure 3. Note: the poles of the electromagnets are in series; they produce maximum magnetic flux. 7. D-The Maxwell Bridge is used for measuring inductance with a low Q. When inductors have a high Q their inductance is measured with a Hay Bridge. 8. B - The ratio of vertical frequency to horizontal frequency is measured as follows. Draw two lines touching the sides as shown in Figure 4. The ratio of vertical to horizontal frequency is equal to V divided by H. In this case: 300 4 400 9. B The Z-axis terminal is conV H = 3 = - nected to the grid or cathode of the CRT. One example of the use of the Z-axis is for marking frequencies during a sweep alignment. When the marker is fed to the Z-axis, there is less chance of it distorting the trace. 10. B- See Figure 5. If the meter reads zero when the switch is open, then it may be defective. However, you must have some knowledge of the circuit. For example, if the fuse is open, the meter reads zero regardless of the switch position. (In that case, put the meter across the fuse.) asw Durable Desoldering Tools Sterling- Brand from Wahl Clipper Corporation Movin Take us with you. Just peel off the subscription mailing label and attach it to the address change card located at the front of this issue. Please allow 6-8 weeks to process your address change. EIEOTROAIO Servicing &Technology High quality at a low price. You pay a little and get a lot. Anti -static or static -free desoldering tools available. End all worries about static electricity harming your components. Replaceable tips last twice as long as regular teflon tips (approximately 2,000 suctions). Easy one -hand operation. Grooved handgrip and curved thumb -holder reduce fatigue during long desoldering operations. Self-cleaning. Plunger clears the tip of hardened solder. You'll always get a high -vacuum suction. For more information on antistatic or staticfree desoldering tools, or our full line of soldering irons, call or write. WAHL CLIPPER CORPORATION 2900 Locust Street Sterling, Illinois 61081 (815) 625-6525 Sterling^ is a trademark of Wahl clipper Corporation. Circle (25) on Reply Card August 1986 Electronic Servicing & Technology 63 Audio Corner Mention the word microcomputer and most folks think of the typical CRT, keyboard, disk-drive combination that they've seen in the office or on television. Ask the typical individual how many computers he has at home, and he'll likely say none. But if he owns a late model receiver, cassette deck or VCR, he probably owns several dedicated microcomputers, for they proliferate in audio and video products. Granted, the micros inside consumer equipment are dedicated: that is, can perform only functions related to the device they control. That's why there's no console or CRT display. They are preprogrammed. From the owner's point of view, they are hidden or transparent. So, love them or hate them, you still have to deal with microcomputers if you service today's home electronics. This article will discuss the basic makeup of dedicated micros, show what products make use of them and why, and offer tips for those of us who have the pleasure of servicing them. By Kirk VistainW mability allows manufacturers to produce a wide range of products with similar chassis types, thus cutting production costs. By programming the processors differently, and perhaps adding a subassembly here and there, a variety of products at different price points can be produced inexpensively, giving the consumer an apparently wide choice, and the manufacturer a more comprehensive market. BASIC MICROCOMPUTER CLOCK MICRO- -10 PROCESSOR UNIT (MPU) DATA BUS MEMORY ADDRESS sus MEMORY Terminology We often hear the terms microprocessor, microcomputer and microcontroller used interchangeably. To prevent confusion, let's try to define each one. For the following discussion, refer to Figure 1. The most elementary microcomputer comprises three separate blocks: 1. microprocessor; 2. memory; 3. interface adapter. The microprocessor performs arithmetic, logical and control operations for the system. As you can see, the processor is part of a microcomputer, and, strictly speaking, the two terms are not synonymous. All the same, you may notice that some technicians, as well as manufacturers, confuse the two. There are two kinds of memory used by the processor. ROM is programmed during manufacturing and can be read only, and normally contains the program, or set of instructions, that configures the microcomputer for a given function. More sophisticated devices also use RAM, which can be written into as well as read, to store temporary information, such as switch settings. The interface adapter buffers and conditions signals to and from the outside world. It offers the processor a measure of protection from externally caused damage and translates between the signals understood by in/out devices and those produced by the processor. I/O devices are the solenoids, motors, sensors and indicators that communicate with the processor. Some units have I/O expanders attached to them that allow the micro to control more devices than it has outputs. So the term microcomputer is really quite accurate when applied to the controllers inside modern home entertainment equipment. They all have a microprocessor command center, memory (although not much) and an I/O interface. Why use them? Because they are complex and, though generally reliable, sometimes cause puzzling failures, microcomputers may seem to be a bit of overkill for consumer devices. So why are they so popular? One reason is that customers love a wide variety of flashing lights and esoteric functions (or at least the manufacturers think so). The microcomputer is perfectly suited to this sort of thing. It also helps manufacturers offer consumers a large variety of units at different price points. The micro's program64 Electronic Servicing & Technology August 1986 INTERFACE ADAPTER DO ICROCOMPUTER Figure 1. PORT INPUTI OUTPUT DO DEVICE TYPICAL KEY MATRIX KEY MATRIX CHART IN K. K, K. FF REV DOLBY S. REW MEM VOL. DN. S, PLAY REG VOL UP OUT S. Figure 2. The micro replaces thousands of discrete transistors, reducing parts count. For a dramatic example of this, take a look at a full logic cassette deck from the late '70s, then compare it to this year's models. Gone are the separate logic boards with 20 or 25 discrete TTL chips plus a few dozen transistors. All are now replaced by a couple of LSI (large scale integration) packages and a handful of driver transistors. Fewer parts should mean less trouble and easier repair if something goes wrong. Servicing There are many good books that describe the inner workings of microcomputers, so we'll skip that for now. Troubleshooting is done using a black box approach. We find out what's supposed to go in and what should come out. If the inputs are there and the output isn't, the chip is probably bad. If the inputs aren't there, back up to the previous stage. Program Number Most microprocessor ICs have a designation such as LM6413E-027. The number to the left of the dash is the type; the one to the right is a program number. The same device may be used in a television or a cassette deck, but the program numbers will be different. It is important to ensure that you have a chip with the correct program or it won't work. Power Supply and Clock Troubleshooting begins with, what else, checking supply voltages. They should be within 10% of their nominal value, with no ripple. Next check the clock. A microprocessor generally needs a clock to synchronize its operation. If the clock is bad, the chip won't function. A clock is really just a tightly controlled crystal oscillator. Look for proper amplitude and frequency. In'Out Several input schemes are used to provide commands to the microcomputer: 1. Constant do voltage (high or low); 2. momentary connection to high or low dc; 3. scan. Before we elaborate, a quick tip -you can usually tell from the schematic what polarity of signal should appear at a particular pin. A bar over a function means it is active low. No bar normally means it is active high. Constant do voltages are easy to check. They are there or not. So are momentary do levels. Just activate the switch or other input in question and see if the input pin gets the signal. If not, the driving circuitry may be bad. Scanned inputs are more difficult to test, but in general, you'll need a scope. See Figure 2. Instead of using fixed do voltages, a scanned input scheme takes a coded output from the microprocessor and connects it to the input pin selected by a switch. To test one, use the oscilloscope to see if the signal from the scan pin connected to the switch in question is sent to the appropriate input pin when the switch is activated. You'll probably just see a train of square waves, which are difficult to decipher, but you don't have to. It's enough to know that the pulse train is getting to the pin. No static Nothing ruins a day on the bench like trashing the expensive 24-pin IC you've been waiting several weeks for. So, by all means, take care to prevent static damage. Most microcomputers are CMOS devices, inordinately sensitive to high voltage static charges, which punch through the gate insulator. Use a grounded work surface and iron, as well as a wrist strap connected through the 1M0 resistor to ground. Leave the chip in the conductive foam it's shipped in until just before it's installed. Then take care not to touch the pins while inserting it into the board. In most cases, these precautions are adequate. But if you work in a dry environment, and can draw an arc from the doorknob after shuffling across the carpet, think about humidifying the shop. Computerized operation is nearly standard on even the least expensivè audio and video equipment. Many sophisticated functions, which you couldn't have had for $2,000 just a few years ago, are currently available in $100 cassette decks. No matter how you feel about computers, you can't get away from them in the servicing business. Now is the time to study them and learn to boost your productivity for the present and future. @5W" CABLE TV CONVERTERS & EQUIPMENT. Plans and parts. Build or buy. Send S.A.S.E. C&D Electronics, P.O. Box 1402, Dept. ES&T, Hope, Arkansas 71801. 1-86-tfn TV TROUBLE ANALYSIS TIPS. Over 300 symptoms/ remedies by circuit area; tough ones over the years. Save time and money. Send $12.50 to CHAN TV, 8151 Grandview Rd.. Chanhassen, MN 55317. 1-85-tfn SONY-TRINITRON REBUILTS are now available. Call for price & delivery, 1-716-621-5250. 7-86-tfn Advertising rates in the Classified Section are 75 cents per word, each insertion, and must be accompanied by payment to insure publications. - VCR REPAIR? Do not miss this one!! TECH TIPS Complete volume all brands. Rush $7.95 to: R. `hood, 420797th Ave. E, Parrish, FL 33564. 7-86-2t - COMPUTERSISOFTWAREITV'slvideo cameras/calculators/typewriters/postage stamps -slightly used, fully guaranteed. Name needs! POB 26900-EST, Los Angeles 90026-0900. 8-86-1t COMPLETE EQUIPMENT FOR TV and Radio service shop. 15 instruments with instruction manuals. Supply of resistors, capacitors, and miscellaneous items. Two filing cabinets with Sams. Call (314) 437-2208, or write Burchard, Owensville, MO 65066. 8-88 -lt ANDREWS '/a INCH 50 ohm hellax rf cable. Brand new, never used. 1,300 feet $900.00 plus shipping. Will ship Freight collect. PH 619-690-1774. Leave Number. 8-86-1t Each initial or abbreviation counts a full word. TV TROUBLESHOOTING: Minimum classified charge is $15.00. For ads on which replies are sent to us for forwarding (blind ads), there is an additional charge of $25.00 per insertion to cover department number, processing of replies, and mailing costs. 32578. 5-86-61 Classified columns are not open to advertising of any products regularly produced by manufacturers unless used and no longer owned by the manufacturer or distributor. PICTURE TUBE REBUILDING EQUIPMENT -All you need to rebuild any color CRT including Sony. Original cost $4500 -will take $2900. Training available. Call KAZ: 305-275-9543. 7-86-2t FOR SALE INDIVIDUAL PHOTOFACT FOLDERS (not sets) #1 to #1400, $3.00 first-class postpaid. Loeb, 414 Chestnut Lane, East Meadow, NY 11554. 8-86-61 AUTOMOBILE RADIO and tape replacement parts. Delco, Chrysler, Philco-Ford, Motorola, Panasonic and many others. Large inventory. Laran Electronics, Inc., 3768 Boston Road, Bronx, NY 10469. (212) 881-9600. National (800) 223-8314, NY State (800) 446-4430. FOR SALE: TV Sales & Service. Established 1941. Owner retiring. Turn -Key price, $15,000. Very low rent. Elkin, NC. 919835-4353 Day, 919-835-2302 nite. 1-85-f f n DISCOUNT CATV CONVERTERS/DECODERS and video accessories. Solar cells for remote power and battery charging applications. Send for free information and prices could save you big money on your next purchase of these and other CATV items. Easy View, P.O. Bott 221, Arlington Heights, Illinois 60006 (312) 952-8504. Ask for Rudy Valentine. 8-86-11 BOOTLEGGERS BIBLE for CB Modification $12.95, CB Radio Repair $10.95. Linear Amplifier Planbook $14.95, kits, etc. Catalog $1.00 refundable-APS, POB 12-84-tfn 263 Newport, R.I.02840 401-846-5627. SCRAMBLED TELEVISION, encoding/decoding. New book. Theory/circuits, $9.95 plus $1 shipping. Work shop, Box 393ES. Dept. E, Bethpage, NY 11714. 1-85-t fn 8 -86 -lt -It TUBES. Unused, in original boxes. Thousands in stock. SASE to Fala Electronics, P.O. Box 1376-3, Milwaukee, WI 53201. HELP WANTED Over 100 ILLUSTRATED problems -solutions of difficult repairs. Also, 12 steps to easier TV repair, $12.00. REMARKABLE DIAGNOSTIC TOOL: Determine operation of high voltage circuits every time. You will not be mistaken about your conclusions, $5.00. Jones, Box 702, Niceville, Fla. 8-86-31 CAMERA -VIDEO Technicians needed. Top pay and benefits for well trained and experienced technicians who are expert with consumer and/or industrial cameras and VCR's. Training by manufacturers such as Sony, Hitachi. Panasonic, etc., are necessary for job experience. Come to sunny Florida and enjoy your work & leisure time. Write or call ATLANTIC ELECTRONICS INC., 1881 NE 26 St., Ft. Lauderdale, FL 33305. (305) 564-8274 10 AM to 6:30 PM. Ask for Dave or Joe. 8-85-tfn VIDEO/AUDIO technician needed. Top pay and benefits for well trained and experienced technicians who are expert with consumer TV and audio equipment. Training by manufacturers such as: Sony, Hitachi, RCA, Panasonic, etc. are necessary for job experience. Write or call: Atlantic Electronics, Inc., 1881 NE 26th St., Ft. Lauderdale, FL 33305, 305-564-8274 (10 AM 6:30 PM). Ask for Dave or Joe. 06-86-tfn BUSINESS OPPORTUNITIES WORKING PARTNER needed to expand present business. Pay 'n down & balance from profits. Precision Picture Tube. Rochester, NY 14612, (716) 621-5250. 7-86-tf n TV SALES & SERVICE -Prosperous 30 year business, with home. TV -VCR -Satellite antennas. Small city in farming, recreational area in Northwest Wis. Service ability essential. Retiring. Can help with financing. 715-822-8408. 8-86-1t August 1986 Electronic Servicing & Technology 65 Bus. Opportunity (Cont.) 3 HRS FROM Advertisers' Index SAN FRANSISCO in pine forested foothills, electronic repair business. Poor health forces sale. Bldg./shop/equipmt. & 7 rm. residence wllg. garden, was $165K, now $155K. (916) 872-1962. 12185íf n T.V. SALES & SERVICE. Well established business located northern Virginia. Owner retiring and will help with financing. Call 703-972-7027 after 7:00 p.m. EST. 06-86-61 Page Number Beckman Industrial Corp. Caig Laboratories, Inc Cleveland Institute of Electronics SERVICES REPAIR OF ZENITH CIRCUIT BOARD 9 -160-all; with dud exchange $33.00. One year guarantee. Kinirral Electroics, 68-26 64th Place, Glendale, N.Y. 11385. 8-86-3t (718) 366-3859. N 11 Circle (31) on Reply Card Tech Guiri e To Pricin lilt "Tech's Guide To Pricing" updated new 5th edition...a framework for setting rates that apply to Hi -Tech pro- 5 800/321-2155 5 Digitron Electronic 57 23 800/526-4928 ETA 59 7 6 800/227-3800 15 8 800/645-9518 SC ET 1,2 516/231-6900 49 18 800/543-4330 4 312/687-2265 3 817/921-9061 Philips ECG 11 7,27,28 ....800/225-8326 Philips ECG 11 29,30 800/225-8326 Precision Picture Tubes 66 34 716/621-5250 Projector Recorder Belt Corp. 66 31 800/558-9572 PTS Corp 53 21 812/824-9331 RCA Distributor and Special Products 17 9 Sams, Howard W. & Co., Inc. 61 26 Sencore, Inc 41,43 guarantees SUCCESS' Sencore, Inc 45,47 Call Toll Free for details f/5 1-800-228-4338 csT Simpson Electric Co ducts...a formula that (32) on Reply Card DANDY-DAPTER'" PATENTED CRT ADAPTER-Don't buy another socket for your CRT Tester! This is the Only way you can win the Socket War! Guaranteed to fit your tester & allow you to test/clean/restore ANY Color, B/W. Projection, Scope or Camera CRTs. Visa/M-Card. Checks, CODs. New Low Price $59.95 (We pay UPS) 1(800) 331-9658. DANDY ELECTRONICS. 2323 GIBSON. MUSKOGEE, OK 74403. 4,51 800/428 -SAMS 14,15 800/843-3338 16,17 800/843-3338 3,19 312/687-2265 Sperry AW Instruments Inc 27 11 800/645-5398 Sperry Tech, Inc. 66 32 800/228-4338 Synchronicity Research Company 59 24 405/628-3695 Tektronix, Inc. Circle (33) on Reply Card 817/921-9101 59 IFC 55,57 N ES DA PROJECTOR RECORDER BELT Whitewater, WI 53190 TLX 4994411 PRBUSA 619/743-7143 806/359-0329 Diehl Enterprises Mercer Electronics 200 Clay Street 55 800/331-9658 MCM Electronics PRB a[KAC 714/671-4800 22 10 Leader Instrument Corp. wis 1-800-242-9553 13 33 I CALL TOLL FREE 1-800-558-9572 39 66 Fordham Radio Supply Co. SERVICE ON OVER 7,000 ELECTRONIC COMPONENTS & PRODUCTS... Advertiser Hotline 21,23,25 Dandy Mfg. Co. Fluke, John Mfg. Co., Inc PERSONALIZED 24 -HOUR Reader Service Number IBC 3 U.S. Instrument Rentals 52 20 800/824-2873 Viz Test Equipment 29 12 800/523-3696 Wahl Clipper Corp. 63 25 815/625-6525 Zenith BC NATIONAL REBUILT HEADQ. FOR- SONY REBUILT PICTURE TUBES 2 YR. WARR.-FREE U.P.S.- DEL ELemnewe . Servicing &Tedlrlology 716-621.5250 KANSAS CITY, MISSOURI Greg Garrison, Sales Manager P.O. Box 12901 Overland Park, KS 66212 Phone: 1-913.888-4664 Circle (34) on Reply Card ELECTRONIC SERVICING & TECHNOLOGY Volume 6, No. 8 (USPS 462-050) is published monthly by Intertec Publishing Corp.. 9221 Ouivira Road. P.O. Box 12901. Overland Park. KS 66212. Second Class Postage paid at Shawnee Mission. KS. and additional mailing offices. POSTMASTER. Send address changes to ELECTRONIC SERVICING & TECHNOLOGY. P.O. Box 12952. Overland Park. KS 662129981. 66 Electronic Servicing & Technology NORWOOD, AUSTRALIA Hastwell, Williamson, Rouse PTY. LTD. P.O. Box 419 Phone: 332-3322 Telex AA 87113 August 1986 LONDON, ENGLAND Nicholas McGeachin Suite 460, Southbank House Black Prince Road, London SE1 7SJ Telex: 295555 LSPG Telephones: Central Line 01 582-7522 Direct Line 01 587-1578 TOKYO, JAPAN EMS, Inc. Sagami Bldg., 4-2-21, Shinjuku, Shinjuku-ku, Tokyo 160, Japan (03) 350-5666 Telex: 2322520 EMSINCJ Cable: EMSINCPERIOD New GPS Series: Tek sets the pace with SmartCursorsM and push-button ease. Work faster, smarter, with two new general purpose scopes from Tektronix. The fou' channel, 100 MHz 2246 and 2245 set the new, fast pace for measurements at the bench or in the field. They're easy to use and afford, by design. On top: the 2246 with exclusive integrated push-button measurements. Measurements are accessed through easy, pop-up menus and implemented at the touch of a button. Measure peak volts, peak-to -peak, ± peak, dc volts and gated volts with new handsoff convenience and on -screen readout of values. SmartCursors T" track voltmeter measurements in the 2246 and visually indicate where ground and trigger levels are located. Or use cursors in the manual mode for immediate, effortless measurement of waveform parameters. Both scopes build on performance you haven't seen at the bandwidth or prices. Lab grade features include sweep speeds to 2 ns/div. Vertical sensitivity of 2 mV/div at full bandwidth for Features Bandwidth No. of Channels Scale Factor Readout SmartCursors`" Volts Cursors Time Cursors Voltmeter Vertical Sensitivity Max. Sweep Speed Vert/Hor Accuracy Trigger Modes 2246 2245 100 MHz 100 MHz 4 4 Yes Yes Yes No Yes No Yes No No Yes mV/div 2 ns/div 2 ns/div 2% 2% Auto Level, Auto, Norm, TV Field, TV Line, Single Sweep No Yes 6.1 kg 6.1 kg 2 mV/div Trigger Level Readout Weight Warranty 3 -year on low-level signal capture. Plus trigger sensitivity to 0.25 div at 50 MHz, to 0.5 div at 150 MHz. Accuracy is excellent: 2% at vertical, 2% at horizontal. And four-channel capability includes two channels optimized for lo9ic signals. Best of all, high performance comes with unmatched convenience. You can see it and feel it the -in 2 parts and labor including CRT responsive controls and simple front panel design, in extensive on -screen scale factor readouts, and in simplified trigger operation that includes Tek's Auto Level mode for automatic triggering on any signal. Contact the Tektronix office or sales representative nearest you for complete details. Each scope is backed by Tek's three-year warranty, plus excellent documentation, training programs and outstanding service sup- port-worldwide. Featuring four channels, flexible triggering, extensive CRT readouts and push-button ease of use, the new Tek 2246 (left) and 2245 (above) bring high -quality, low-cost analysis to diverse applications in digital design, field service and manufacturing. Téktronbco t .[ Copyright ©1986, Tektronix, Inc. All rights reserved. TTA-469 Circle (3) on Reply Card 1MMI I rE0 TO EXCELLENCE You bet you can make it big in the consumer electronics business by selling_ Zenith Video/Audio Accessories to the same people whose electronic products you now service. experienced Zenith Accessory Sales Manager...the selling power of the Zenith name on video and audio accessories..,and the overall support of your Zenith distributor's dedicated personnel. With easy access to this wealth of know-how, you should have no trouble turning some 6, 7 or 8 feet of your floor space into a very respectable profit center. With Zenith Electronic Accessories, of course. Call your Zenith distributor's Accessory Sales Manager now or write direct for the name of the Zenith distributor serving your area. Call or write now, today! e Like all Zenith products, Zenith Audio/Video Accessories are made to the same uncompromising quality and performance standards that have earned Zenith a reputation unsurpassed in consumer electronics. And it goes without saying that the better known and the more respected a product's name the easier, faster, and the more profitably you can sell it across the counter ...or while you're out of the shop on a service call. To learn how it's done, how other service techs just like you are cashing in on the selling power of the Zenith name, call your Zenith distributor's Accessory Sales Manager now. Everything you need is there at your Zenith distributor's place the help and encouragement of an FN/FN - The quality goes in before the name goes on.® Zenith Service, Parts & Accessories Department 30.11000 Seymour Avenue, Franklin Park, Illinois 60131 A Division of Zenith Electronics Corporation a -fEN/TN lial9. cleteeta .r .. mom .. 'M...r C3 irÿ( :e r.r `.r IMO EA P 1 . la .r rr tdela\or\e ur.ce ÉN/TH Yi ,.. «S 11 i N 9r ?If `.1 SR. Y. t1 +vl 'mom 139.115, ':-.."¡T, 'AM -. - ,. . if -wan emu i. C ,a1»MI dill' 1Oí4.lÍ um ma eon ' i '". 37i rm.. r_. r. VI i arel ai7 t'I't iin. 'vY' y . - WM r- : video (1CCESSorYCS WM .. .. - - . - : s,.. . . mime . . .. . - - ..... 4:. .. : i pEpLE 0,li5 be,» zsN/rN i ..>>0 i-120