Service Manual Speed Oven Model Dso 500

Transcript

Service Manual SPEED OVEN MODEL DSO 500 Please read this manual completely before attempting to install, operate or service this equipment This manual is Copyright ©2011 Duke Manufacturing Company. All rights reserved. Reproduction without written permission is prohibited. Duke is a registered trademark of the Duke Manufacturing Company. Duke Manufacturing Company 2305 N. Broadway St. Louis, MO 63102 Phone: 314-231-1130 Toll Free: 1-800-735-3853 Fax: 314-231-5074 www.dukemfg.com P/N 168465B Service Manual for Speed Oven Model DSO 500 2 SAFETY PRECAUTIONS SAFETY PRECAUTIONS PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY (a) Do not operate or allow the oven to be operated with the door open. (b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary. (1) interlock operation (2) proper door closing (3) seal and sealing surfaces (arcing, wear, and other damage) (4) damage to or loosening of hinges and latches (5) evidence of dropping or abuse (c) Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections. (d) Any defective or misadjusted components in the interlock monitor, door seal, and microwave generation and transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner. (e) A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner. CAUTION: When servicing the unit, be sure no electrical wires contact a sharp edge. Check all wiring for possible cuts and/or abrasions, which can occur during servicing. 3 Service Manual for Speed Oven Model DSO 500 TABLE OF CONTENTS SAFETY PRECAUTIONS.....................................................................................................................3 INTRODUCTION..................................................................................................................................6 MAIN FEATURES...........................................................................................................................7 INSTALLATION....................................................................................................................................8 UNPACKING OVEN.......................................................................................................................8 RADIO INTERFERENCE...............................................................................................................8 OVEN PLACEMENT......................................................................................................................8 ELECTRICAL INFORMATION........................................................................................................8 EARTHING INSTRUCTIONS.........................................................................................................9 EXTERNAL EQUIPOTENTIAL.......................................................................................................9 SPECIFICATIONS..............................................................................................................................10 INPUT POWER............................................................................................................................10 OUTPUT POWER........................................................................................................................10 DIMENSIONS...............................................................................................................................10 WEIGHT.......................................................................................................................................10 RECOMMENDED CLEARANCES...............................................................................................10 INTERNAL COOKING CAVITY DIMENSIONS............................................................................10 PREVENTIVE MAINTENANCE..........................................................................................................11 CLEANING...................................................................................................................................11 SERVICING PROCEDURES.............................................................................................................12 GENERAL.....................................................................................................................................12 COMPONENT OVERVIEW................................................................................................................13 STIRRER MOTOR AND GEARBOX............................................................................................13 HIGH VOLTAGE TRANSFORMERS............................................................................................15 HIGH VOLTAGE RECTIFIERS.....................................................................................................17 HIGH VOLTAGE CAPACITORS...................................................................................................19 MAGNETRONS............................................................................................................................21 MAGNETRON THERMAL SWITCHES........................................................................................23 SOLID STATE RELAYS................................................................................................................25 MECHANICAL RELAYS AND INTERLOCK SWITCHES.............................................................27 HEATERS AND THERMAL CUTOUTS........................................................................................29 LINE FUSES.................................................................................................................................31 JET PLATES.................................................................................................................................33 CABINET COOLING FANS..........................................................................................................35 4 TABLE OF CONTENTS MAGNETRON COOLING FANS..................................................................................................37 CABINET THERMAL SWITCH.....................................................................................................39 KEYPAD/CONTROL BOARD.......................................................................................................41 INVERTERS.................................................................................................................................43 SYSTEM TESTING............................................................................................................................45 POWER OUTPUT MEASUREMENT...........................................................................................45 MICROWAVE LEAKAGE TEST....................................................................................................45 COMPONENT TESTING....................................................................................................................47 POWER TRANSFORMER TEST.................................................................................................47 DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN.......................48 HIGH VOLTAGE CAPACITOR TEST...........................................................................................49 HIGH VOLTAGE RECTIFIER TEST.............................................................................................50 MECHANICAL RELAYS AND INTERLOCK SWITCHES.............................................................51 REPAIR PROCEDURES....................................................................................................................53 RELAY AND SWITCH REPLACEMENT.......................................................................................53 LINE FUSE REPLACEMENT.......................................................................................................54 INVERTER REPLACEMENT........................................................................................................55 BLOWER MOTOR REPLACEMENT............................................................................................56 ELECTRICAL PANEL REPLACEMENT.......................................................................................58 MAGNETRON REPLACEMENT..................................................................................................59 STIRRER MOTOR REPLACEMENT............................................................................................60 HEATER ELEMENT REPLACEMENT.........................................................................................61 CABINET THERMAL SWITCH REPLACEMENT.........................................................................62 HIGH VOLTAGE TRANSFORMER REPLACEMENT..................................................................63 FRONT THERMAL COOLING FAN REPLACEMENT..................................................................64 INTAKE AND EXHAUST FANS REPLACEMENT........................................................................65 ADJUSTMENTS...........................................................................................................................66 TROUBLESHOOTING.......................................................................................................................67 SCHEMATIC DIAGRAM.....................................................................................................................71 SPARE PARTS LIST..........................................................................................................................72 APPENDIX A INVERTER PROGRAMMING......................................................................................73 PROGRAMMING PROCEDURE..................................................................................................73 INVERTER SETTINGS................................................................................................................74 5 Service Manual for Speed Oven Model DSO 500 INTRODUCTION 7 3 12 11 2 1 10 6 4 5 10 Figure 1 6 4 8 9 EQUIPMENT OVERVIEW MAIN FEATURES 6. DOOR AND HEAT SHIELD The main features of the Model DSO 500 Speed Oven are identified in Figure 1 and described below. The door is pulled downwards and towards you to open. The door is designed with interlocks for microwave safety. The door should NOT be used to support heavy dishes. It must be kept clean. The door includes a heat shield attached to the front.(See CARE and CLEANING instructions in the OPERATOR’S MANUAL). 1. ON/OFF SWITCH Turning ON the power switch will operate the blower fans, stirrer motor and cooling system. It will also activate the control panel and heat up the oven to the temperature setting, which will display “Oven Ready. NOTE: When the Power Switch is turned “OFF”, the rear mounted Cooling Fans will be running until the unit has cooled down or the power cord removed. 2. CONTROL PANEL This is the electronic control board that is programmable for different menus, temperature setting, variable fan speed, Microwave Power Connection only, Microwave and Convection Combination, etc. This also has some service diagnostics. 7. DOOR SEAL These ensure a seal around the door cavity. They should be kept clean and checked regularly for signs of damage. 8. REMOVABLE BOTTOM JET PLATE The bottom jet plate directs the air from the bottom of the oven to the underside of the product. 9. DRAIN OUTLET AND PLUG Remove drain plug when cleaning. (See CARE and CLEANING instructions in the OPERATOR’S MANUAL). Make sure it is replaced into position before replacing bottom jet plate. 3. DRAIN PAN 10. AIR OUTLETS This serves as the collector of any liquid from the Oven cavity during cooking or cleaning. These air outlets and louvers on the left side, right side and rear panels are part of the cooling system of the electrical components. They must be kept free from obstruction. It will not allow microwave energy to escape into the environment. See clearance allowances specified in the INSTALLATION Section of this manual. 4. OVEN CAVITY The oven cavity is constructed from stainless steel and must be kept clean. (See CARE and CLEANING instructions in the OPERATOR’S MANUAL). The top cavity has a thin jet plate and the bottom cavity has the wire rack and bottom jet plate. A drain plug is also provided for ease of cleaning. 5. CONVECTION FAN The unit has two blower systems (Top and Bottom) for distributing the patented impingement air system. Both blower systems can be operated independently over the entire speed range for more precise control of cooking, browning, etc. The perforated rear panel and the bottom jet plates must be kept clean and free of debris. (See CARE and CLEANING instructions in the OPERATOR’S MANUAL). 11. EXHAUST VENT The exhaust vent is at the rear of the oven. This enables steam to escape and prevents build up of condensation. It will not allow microwave energy to escape into the environment. 12. COOLING FANS Cooling Fans above the power cord are mounted to bring in cool air from the room into the machinery compartment. The single fan below the exhaust vent is directed to blow out the air from the machinery compartment. 7 Service Manual for Speed Oven Model DSO 500 INSTALLATION UNPACKING OVEN • Inspect oven for damage such as dents in door or inside oven cavity. • Report any dents or breakage to source of purchase immediately. Do not attempt to use oven if damaged. • Remove all materials from oven interior. • If oven has been stored in extremely cold area, wait a few hours before connecting power. A. Allow at least 3” (7.62 cm) of clearance around the sides of oven. Proper airflow around the oven cools electrical components. With restricted airflow, the oven may not operate properly and the life of electrical parts is reduced. B. Install oven so oven bottom is at least 3 feet (91.5 cm) above floor. RADIO INTERFERENCE Microwave operation may cause interference to radio, television, or similar oven. Reduce or eliminate interference by doing the following: • Clean door and sealing surfaces of oven according to instructions in Care and Cleaning instruction in the OPERATORS MANUAL • Place radio, television, etc. as far as possible from oven • Use a properly installed antenna on radio, television, etc. to obtain stronger signal reception OVEN PLACEMENT • Do not install oven next to or above source of heat, such as pizza oven or deep fat fryer. This could cause microwave oven to operate improperly and could shorten life of electrical parts 8 • Install oven on level countertop surface • If provided, place warning label in a conspicuous place close to microwave oven • Outlet should be located so that plug is accessible when oven is in place • Provide clearance as shown in Figure 2 and described in the following paragraphs “A” and “B” Figure 2. Oven Clearance Dimensions ELECTRICAL INFORMATION The switching operation of this microwave oven can cause voltage fluctuations on the supply line. The operation of this oven under unfavorable voltage supply conditions can have adverse effects. This device is intended for the connection to a power supply system with maximum permissible system impedance Zmax of 1.1 Ohm at the interface point of the user’s supply. The user has to ensure that this device is connected only to a power supply system, which fulfills the requirement above, If necessary, the user can ask the public power supply company for the system impedance at the interface point. The circuit breakers used in this oven are Type C. EQUIPMENT OVERVIEW WARNING TO AVOID RISK OF ELECTRICAL SHOCK OR DEATH, THIS OVEN MUST BE GROUNDED AND PLUG MUST NOT BE ALTERED. WARNING IMPROPER USE OF THE GROUNDING CAN RESULT IN RISK OF ELECTRICAL SHOCK.” CONSULT A QUALIFIED ELECTRICIAN OR SERVICEMAN. IF THE GROUNDING INSTRUCTIONS ARE NOT COMPLETELY UNDERSTOOD, OR IF DOUBT EXISTS AS TO WHETHER THE APPLIANCE IS PROPERLY GROUNDED, AND “DO NOT USE AN EXTENSION CORD. IF THE POWER SUPPLY CORD IS TOO SHORT, HAVE A QUALIFIED ELECTRICIAN OR SERVICEMAN INSTALL AN OUTLET NEAR THE APPLIANCE. If the product power cord is too short, have a qualified electrician install a three-slot receptacle. This oven should be plugged into a separate circuit with the electrical rating as provided in product specifications (available on Duke’s Wavelink website). EXTERNAL EQUIPOTENTIAL Earthing Terminal (export only) Equipment has secondary earthing terminal. Terminal provides external earthing connection used in addition to earthing prong on plug. Located on outside of oven back, terminal is marked with this symbol. WARNING EARTHING INSTRUCTIONS WARNING OVEN MUST BE GROUNDED. Grounding reduces risk of electric shock by providing an escape wire for the electric current if an electrical short occurs. This oven is equipped with a cord having a grounding wire with a grounding plug. The plug must be plugged into an outlet that is properly installed and grounded. Consult a qualified electrician or service provider if grounding instructions are not completely understood, or if doubt exists as to whether the oven is properly grounded. CAUTION: Do not use an extension cord. DO NOT REMOVE EARTHING PRONG WHEN INSTALLING EARTHED APPLIANCE IN A LOCATION THAT DOES NOT HAVE THREE WIRE EARTHING RECEPTACLE, UNDER NO CONDITION IS EARTHING PRONG TO BE CUT OFF OR REMOVED. IT IS THE PERSONAL RESPONSIBILITY OF THE EQUIPMENT OWNER TO CONTACT A QUALIFIED ELECTRICIAN AND HAVE PROPERLY EARTHED THREE PRONG WALL RECEPTACLE INSTALLED IN ACCORDANCE WITH APPROPRIATE ELECTRICAL CODES. Wire Color Code The standard accepted color coding for earthing wires is Green or green with a yellow strip. WARNING EARTHING LEADS ARE NOT INTENDED TO CARRY CURRENT IN NORMAL OPERATION. The service technician must replace all earths prior to completion of the service call. Under no condition should earth wire be left off causing a potential hazard to service technicians and consumer. 9 Service Manual for Speed Oven Model DSO 500 SPECIFICATIONS Table 2 lists the specifications for the Model DSO 500 Speed Oven. Table 2. Specifications MODEL NO. DSO 500 INPUT POWER Operating Voltage Current Phase Circuit Breaker 208 – 240 VAC, 60 Hz 29 Amps Single 30A, Type C or D OUTPUT POWER Microwave Heaters 1600 Watts 5400 Watts DIMENSIONS Height Width Depth 26 in. (with 4 in. legs) 25 7/8 in. 31 in. (incl. door handle) WEIGHT Unpacked Packed Approximately 250 lbs. 360 lbs. RECOMMENDED CLEARANCES Height Width Depth None required 3 inches on each side None required INTERNAL COOKING CAVITY DIMENSIONS Height Width Depth 10 8 in. 16 in. 14-1/2 in. EQUIPMENT OVERVIEW PREVENTIVE MAINTENANCE CLEANING Stainless Steel Care and Cleaning To prevent discoloration or rust on stainless steel several important steps need to be taken. First, we need to understand the properties of stainless steel. Stainless steel contains 70-80% iron which will rust. It also contains 12-20% chromium which forms an invisible passive film over the steels surface which acts as a shield against corrosion. As long as the protective layer is intact, the metal will not corrode. If the film is broken or contaminated, outside elements can begin to breakdown the steel and begin to form rust or discoloration. Proper cleaning of stainless steel requires soft cloths or plastic scouring pads. CAUTION: Never use steel pads, wire brushes or scrapers. Early signs of stainless steel breakdown can consist of small pits and cracks. If this has begun, clean thoroughly and start to apply stainless steel cleaners in attempt to restore the passivity of the steel. WARNING THE POWER MUST BE TURNED OFF AND POWER CORD DISCONNECTED WHENEVER PERFORMING MAINTENANCE OR REPAIR FUNCTIONS. Gasket Maintenance Gaskets require regular cleaning. Gasket cleaning can be done with the use of warm soapy water. Also, never use sharp tools or knives to scrape or clean the gasket which could possibly damager the gasket. Cleaning solutions need to be alkaline based or non-chloride cleaners. Any cleaner containing chlorides will damage the protective film of the stainless steel. Chlorides are also commonly found in hard water, salts and household and industrial cleaners. If cleaners containing chlorides are used, be sure to rinse repeatedly and dry thoroughly upon completion. Routine cleaning of stainless steel can be done with soap and water. Extreme stains or grease should be cleaned with a non-abrasive cleaner and plastic scrub pad. It is always good to rub with the grain of the steel. There are also stainless steel cleaners available which can restore and preserve the finish of the steels protective layer. 11 Service Manual for Speed Oven Model DSO 500 SERVICING PROCEDURES GENERAL The service section of this manual includes a section called component overview. Information on each component is a separate page. This overview is not intended to provide detailed information. Its purpose is to provide a general understanding of what the component does and how it is tested and replaced. When a procedure is to be performed, refer to the detailed REPAIR PROCEDURES. The information in this overview includes the following: 12 • A general description of the function of the component in the oven operation • Location and Access information • Safety Issues • Tools Required • Operational Testing • Test Procedure • Replacement Procedure NOTE: Remember this overview is only intended to provide a brief discussion on each component. Details for testing, adjusting and replacement are provided separately in the TESTING and REPAIR section of this manual and should be referred to when performing any procedure. In addition to the Overview section this chapter includes the following: • Power Output Measurement • Microwave Leakage Test • Component Detailed Testing • Detailed Repair and Replacement Procedures • Adjustment Procedures • Troubleshooting Procedures Additional chapters provide the Schematic Diagram and the Spare Parts list. COMPONENT OVERVIEW COMPONENT OVERVIEW STIRRER MOTOR AND GEARBOX The stirrer motor and gearbox, Figure 3, is located near the front of the oven upper chamber above the upper jetplate. The stirrer motor rotates the stirrer blade at 20 rpm. The rotating stirrer blade evenly distributes the microwave field and the upper hot airflow into the cook chamber to ensure uniformity. Should the stirrer blade cease to rotate during cooking, severe nonuniformity of cooking will be observed. Localized burning of the food may occur and in the case of cooking frozen food, very cold uncooked areas may be detected. Location and access The stirrer motor is centrally located above the top of the cook chamber. The top and side panels will need to be removed. Surface Components Safety issues • Electrical supply of 208/240 VAC to stirrer motor which becomes live when power cord is live • Proximity to High Voltage system (5 kVDC) which can remain live, even after power down • Upper end of motor shaft rotates rapidly with small exposed cooling fan Tools required • Flat blade screwdriver to remove top and side panels • 11/32 inch nut driver to remove nuts securing motor and gearbox to top of oven • Voltmeter • Flash light Operational testing The stirrer motor is powered from the 208/240 VAC mains supply and is not controlled from the main on/off switch on the right hand side. The door safety interlocks interrupt this supply when the door is opened, so that the stirrer blade is stationary whenever the door is opened. The interlock function should be checked by opening and closing the cook door and observing the rotation of the stirrer motor fan. The rotation of the stirrer blade can be checked by removing the upper jet plate or observing the position of the stirrer blade through the air holes in the upper jet plate with a flashlight. Figure 3. High Voltage and Inside Top 13 Service Manual for Speed Oven Model DSO 500 Test procedure Replacement Check 208/240 VAC is present on the motor power connections, wires 47 and 49, as above. After removing the side and top panels and disconnecting the power cord, the stirrer motor power leads can be disconnected. There are four 11/32 inch nuts securing the stirrer motor and gearbox. Upon refitting, align the dnveshaft of the gearbox with the head of the coupling to the stirrer blade. If power is not present, check incoming line voltage, line fuses, mechanical relays K6, K8 and primary and secondary door switches. If power is present at all times, the door interlock safety system has failed. Check the mechanical relays K6, K8 and primary and secondary door switches. STIRRER MOTOR AND GEARBOX - NOTES 14 COMPONENT OVERVIEW HIGH VOLTAGE TRANSFORMERS The transformers, Figure 4, step up the input line voltage to 2.5 kV. This voltage is rectified by the high voltage diodes and the high voltage capacitors for operation of the magnetrons. Location and Access The transformers are centrally located above the top of the cook chamber. The top and side panels will need to be removed. Safety Issues WARNING THE HIGH VOLTAGE CAPACITORS RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to transformers when POWER switch is in ON position and oven doors are closed Tools Required. • Flat blade screwdriver to remove top and side panels • 3/8 inch nut driver to remove nuts securing transformers to top of oven • Voltmeter Operational Testing. Figure 4. High Voltage Transformers The transformers are powered from the 208/240 VAC mains supply through solid state relays K4 and K5 and mechanical relay K6 and K8. Relays K6 and K8 are controlled by the door safety interlock requiring the oven door to be closed to provide primary voltage to the transformers. The door safety interlocks interrupt this supply when the door is opened. Operation of relays K4 and K5 required the POWER switch to be in the ON position to provide operating voltage to the control board. The interlock function can be checked by opening and closing the oven door and observing the rotation of the blade on top of the stirrer motor. 15 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement WARNING WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING. REFER TO DETAILED PROCEDURE IN THE COMPONENT TESTING SECTION BEFORE TESTING. THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. NOTE: Dangerous voltages can be present at this component. Refer to detailed test procedure for testing this component. Check 208/240 VAC is present on the transformer primaries, wires 26 and 45 for mag #1 transformers and wires 27 and 48 for mag #2 transformer. After removing the side and top panels and disconnecting the power cord, the transformer primary and secondary leads can be disconnected. There are four 3/8 inch nuts securing the transformers. If power is not present, check incoming line voltage, line fuses, mechanical relays K6, K8 and primary and secondary door switches. If power is present at all times, the door interlock safety system has failed. Check the mechanical relays K6, K8 and primary and secondary door switches and POWER ON/OFF switch. HIGH VOLTAGE TRANSFORMERS - NOTES 16 COMPONENT OVERVIEW HIGH VOLTAGE RECTIFIERS The high voltage diodes, Figure 5, rectify the incoming 2.5 kV voltage and doubles it providing 5kVDC for magnetron operation. Location and Access The diodes are located above the top of the cook chamber at the rear of the oven. The top and side panels will need to be removed. Safety Issues WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to transformers when POWER switch is in ON position and oven doors are closed Tools Required • Flat blade screwdriver to remove top and side panels • Phillips #2 screwdriver to remove screws securing diodes to top of oven • Ohmmeter to check diodes Operational Testing Figure 5. High Voltage Rectifiers The transformers connected to the diodes are powered from the 208/240 VAC mains supply through solid state relays K4 and K5 and mechanical relay K6 and K8. Relays K6 and K8 are controlled by the door safety interlock requiring the oven door to be closed to provide primary voltage to the transformers. The door safety interlocks interrupt this supply when the door is opened. Operation of relays K4 and K5 require the POWER switch to be in the ON position to provide operating voltage to the control board. The interlock function can be checked by opening and closing the oven door and observing the rotation of the blade on top of the stirrer motor. 17 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement WARNING WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING. REFER TO DETAILED PROCEDURE IN THE COMPONENT TESTING SECTION BEFORE TESTING. HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING THE TRANSFORMERS NOTE: Dangerous voltages can be present at this component. Refer to detailed test procedure for testing this component. After removing the side and top panels and disconnecting the power cord, the diode leads can be disconnected. There are two screws securing each diode. Disconnect the wires to the diodes. Use an ohmmeter to check diodes. Diodes should conduct in one direction showing low resistance and not conduct in the reverse direction, thus indicating a very high resistance. High or low resistance in both directions indicates a defective diode. HIGH VOLTAGE RECTIFIERS - NOTES 18 COMPONENT OVERVIEW HIGH VOLTAGE CAPACITORS The high voltage capacitors, Figure 6, store the rectified high voltage (2.5 kVDC) for operation of the magnetrons. Location and Access. The capacitors are located above the top of the cook chamber at the rear of the oven. The top and side panels will need to be removed. Safety Issues WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to transformers when POWER switch is in ON position and oven doors are closed • Capacitors charge to the 2.5 kVDC level when the high voltage circuit is properly operating Tools Required • Flat blade screwdriver to remove top and side panels • 5/16 inch nut driver to remove nuts securing diodes to top of oven • Ohmmeter to check capacitors Operational Testing Figure 6. High Voltage Capacitors The capacitors charge whenever the transformer is operating. The transformers connected to the diodes for charging the capacitors are powered from the 208/240 VAC mains supply through solid state relays K4 and K5 and mechanical relay K6 and K8. Relays K6 and K8 are controlled by the door safety interlock requiring the oven door to be closed to provide primary voltage to the transformers. The door safety interlocks interrupt this supply when the door is opened. Operation of relays K4 and K5 require the POWER switch to be in the ON position to provide operating voltage to the control board. The interlock function can be checked by opening and closing the oven door and observing the rotation of the fan on top of the stirrer motor. 19 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement WARNING WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING. REFER TO DETAILED PROCEDURE IN THE COMPONENT TESTING SECTION BEFORE TESTING. HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE REPLACEMENT. NOTE: Dangerous voltages can be present at this component. Refer to detailed test procedure for testing this component. Capacitor must be discharged before removal. After discharging, disconnect leads. There are two nuts securing the capacitor bracket. HIGH VOLTAGE CAPACITORS - NOTES 20 COMPONENT OVERVIEW MAGNETRONS The magnetron filament voltage of 4.5 VAC is supplied from the high voltage transformer filament winding. The operating voltage of 5000 VDC is provided by the rectified output from the transformer high voltage winding. Location and Access The magnetrons, Figure 7, are located above the top of the cook chamber at the left and right side of the oven. The top and side panels will need to be removed. Safety Issues WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to transformers when POWER switch is in ON position and oven doors are closed • Capacitors charge to the 2.5 kVDC level when the high voltage circuit is properly operating • The 4.5 VAC magnetron filament supply is at 2500 V relative to the chassis Tools required • Flat blade screwdriver to remove top and side panels • 3/8 inch nut driver to remove nuts securing the magnetrons to top of oven Operational Testing. Figure 7. Magnetrons The magnetrons receive filament and high voltage from the high voltage transformers. The transformers connected to the diodes for charging the capacitors are powered from the 208/240 VAC mains supply through solid state relays K4 and K5 and mechanical relay K6 and K8. Relays K6 and K8 are controlled by the door safety interlock requiring the oven door to be closed to provide primary voltage to the transformers. The door safety interlocks interrupt this supply when the door is opened. Operation of relays K4 and K5 require the POWER switch to be in the ON position to provide operating voltage to the control board. The interlock function can be checked by opening and closing the oven door and observing the rotation of the blade on top of the stirrer motor. 21 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement WARNING WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING. REFER TO DETAILED PROCEDURE IN THE COMPONENT TESTING SECTION BEFORE TESTING. HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE MAGNETRON REPLACEMENT. NOTE: Dangerous voltages can be present at this component. Refer to detailed test procedure for testing this component. Remove cooling duct. (Right side magnetron only). Label and disconnect wires from transformer to magnetron filament. Disconnect wires to thermostat. Remove nuts attaching magnetron to top surface. When installing the new magnetron, be sure metal mesh gasket is properly positioned around the magnetron dipole antenna and that thermostat is installed on magnetron. Secure magnetron to top surface with nuts. Reconnect wires to filament and thermostat. MAGNETRONS - NOTES 22 COMPONENT OVERVIEW MAGNETRON THERMAL SWITCHES The magnetron thermal switches, Figure 8, are used to monitor the magnetron temperature and open the high voltage supply when the temperature exceeds 150°C. Location and Access The magnetrons thermostats are located on the side of each magnetron. The top and side panels will need to be removed. Safety Issues WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to transformers when POWER switch is in ON position and oven doors are closed • Capacitors charge to the 2.5 kVDC level when the high voltage circuit is properly operating Tools required • Flat blade screwdriver to remove top and side panels • 3/8 inch nut driver to remove nuts securing the magnetrons to top of oven Operational Testing The thermostats are connected in the high voltage transformer primary circuit and are normally closed connecting primary voltage on wires 26 and 27 to the high voltage transformer. If magnetron is not operating check continuity across thermostat terminals. Figure 8. Magnetron Thermal Switches 23 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement WARNING WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE SERVICING. REFER TO DETAILED PROCEDURE IN THE COMPONENT TESTING SECTION BEFORE TESTING. HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE MAGNETRON THERMOSTAT REPLACEMENT. NOTE: Dangerous voltages can be present at this component. Refer to detailed test procedure for testing this component. Label and disconnect wires to thermostat. Remove screw securing thermostat to magnetron and remove thermostat. When installing a new thermostat, secure with screw. Connect wires to thermostat. NOTE: Disconnect wires to thermostat and check continuity across thermostat terminals. Continuity should be indicated when thermostat is at normal ambient temperature. MAGNETRON THERMAL SWITCHES - NOTES 24 COMPONENT OVERVIEW SOLID STATE RELAYS Five solid state relays are used. Three relays (K1, K2, and K3) are used to control the heating elements. Two relays (K4 and K5) are used to control voltage to the magnetron high voltage transformer primaries. Location and Access The five solid state relays, Figure 9, are located on the right side of the oven. The right side panel will need to be removed. Tools required • Flat blade screwdriver to remove side panel, relay attaching screws, and terminals connections. Operational Testing The solid state relays are controlled by the control board. Control board operation requires the oven door to be closed. Each solid state relay has a LED indicator that illuminates when the relay is operated. Each heater is controlled separately by either relay K1, K2, or K3. When the magnetrons are to be operated, relays K4 and/or K5 will have the LED illuminated. Test Procedure Disconnect output leads from the relay to be checked. Set program to operate the relay. Check for operating voltage across input terminals. If operating voltage is present LED should be illuminated. Check for continuity across output terminals. After checking, reconnect output leads. Replacement Label and disconnect wires to relay input and output terminals. Remove screws securing relay to oven and remove relay. When installing a new relay, secure to panel with screws. Connect wires to input and output terminals. Figure 9. Solid State Relays RELAY CONTROL FUNCTION Upper Heater Coil Middle Heater Coil Lower Heater Coil HV Transformer 1 Left HV Transformer 2 Right K1 K2 K3 K4 K5 Safety Issues • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch has 208/240 VAC present on the input side whenever the oven is connected to the input power source 25 Service Manual for Speed Oven Model DSO 500 SOLID STATE RELAYS - NOTES 26 COMPONENT OVERVIEW MECHANICAL RELAYS AND INTERLOCK SWITCHES Three mechanical relays are used. These are K6, K7, and K8. The mechanical relays are operated by the door interlock switches “P”, “S”, and “M”. When the oven door is closed, primary door switches P and S are closed and provide voltage to the relay coils of relays K6 and K8. Door switch M should be open. If door switch M is also closed relay K7 operates causing a short circuit ands blowing the line fuses to prevent magnetron operation. Location and Access The three mechanical relays, Figure 10, are located on the right side of the oven. The right side panel will need to be removed. Safety Issues. • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch has 208/240 VAC present on the input side whenever the oven is connected to the input power source Tools required • Flat blade screwdriver to remove side panel, and relay attaching screws. • #2 Phillips screwdriver Operational Testing The mechanical relays are controlled by the three oven door switches P (primary), M (Monitor), and S (Secondary). When the oven door is closed, switches P and S should be closed, energizing relays K6 and K8. At this time switch M should be open, de-energizing relay K7. When relay K6 and K8 are closed, operating voltage is applied to the high voltage magnetron circuits. If switch M is also closed, relay K7 is energized. This shorts the input voltage lines, blowing the line fuses prevent normal circuit operation. A control switch “C: disables the control card when the door is open. This switch should operate at the same time as switch “M”. Test Procedure Close oven door and check that the operating coils of K6 and K8 have the input power source voltage across the coil terminals and that K7 does not have voltage across the coil terminals. Open the oven door and check that no voltage is across the relays K6 and K8 operating coils and that operating voltage is across the coil for relay K7. Figure 10. Mechanical Relays Replacement Refer to detailed procedure in REPLACEMENT SECTION section of this manual. 27 Service Manual for Speed Oven Model DSO 500 MECHANICAL RELAYS AND INTERLOCK SWITCHES - NOTES 28 COMPONENT OVERVIEW HEATERS AND THERMAL CUTOUTS The three heaters, Figure 11A, are used to heat the oven. These heaters are controlled by the control board through relays K1, K2, and K3. The high limit and aux thermal cutouts, Figure 11B, are connected in series with the heaters and the input power source through the line fuses. If the temperature exceeds 274°C all heaters are cutout of the circuit through the aux thermal cutout. If the temperature exceed 302°C the high limit thermal cutout opens and disconnects all the heater elements. Both thermal cutouts are self-resetting. Location and Access The heaters and thermal cutouts are located inside a housing at the right rear of the oven. The right side panel, top panel and rear panel will need to be removed. Figure 11A. Heating Coils Safety Issues WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS WHEN THE TOP COVER IS REMOVED. • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch has 208/240 VAC present on the input side whenever the oven is connected to the input power source Tools required • Flat blade screwdriver to remove panels. • Phillips head screwdriver to remove heater panel and enclosure. 29 Service Manual for Speed Oven Model DSO 500 Figure 11B. Thermal Cutouts Operational Testing The heating elements require the control board to be properly functioning. The solid state relay LED should be illuminated for the heater element to be turned on. When testing the heater elements the temperature in the oven must be less than 274°C so that the thermostats remain closed. Test Procedure Close oven door. Check for operating voltage across heater terminals. Unplug oven and check continuity across heater coils. If a heater coil shows high resistance coil is probably open. Replacement Refer to detailed procedure in the REPLACEMENT section of this manual. HEATERS AND THERMAL CUTOUTS - NOTES 30 COMPONENT OVERVIEW LINE FUSES The line fuses, Figure 12, are in the circuit going to the heater elements and the magnetron circuits and are not in the POWER switch circuit Location and Access The line fuses, Figure 12, are located in the fuse clips on the lower right side of the oven. The right side panel will need to be removed. Tools required • Flat blade screwdriver to remove panels and remove fuses from fuse clips. Operational Testing The line fuses must be operational for the heating elements, magnetron circuit and stirrer motor to function. If any of these components are operational the line fuses are in good condition. Test Procedure Disconnect oven from power source. Remove fuse from fuse clip. Check continuity across fuse. Replacement Install fuse into fuse clip. Figure 12. Line Fuses Safety Issues • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source 31 Service Manual for Speed Oven Model DSO 500 LINE FUSES - NOTES 32 COMPONENT OVERVIEW JET PLATES The jet plates are used to direct the hot airflow at high speed over the food in the cook chamber of the oven. The upper jet plate is transparent to microwaves, to permit the microwaves to radiate downwards into the food. Location and Access The jet plates, Figure 13, are located inside the oven cavity at the top and the bottom. Open the oven door to gain access. Tools required • Upper Jet Plate: Allen wrench 5/32 inch • Lower Jet Plate: Flat blade screwdriver or flat knife. Replacement Upper Jet Plate 1. Remove front two Allen head screws from white circular clamps on upper surface of cook chamber. 2. Loosen rear two Allen head screws in white circular clamps. 3. Carefully withdraw black PTFE coated mica upper jet plate to front of oven. 4. Using a flat blade screwdriver or flat knife, lever metal lower jet plate upwards and withdraw. Figure 13. Jet Plates Safety Issues • Hot ovens can burn. Allow oven to cool before servicing • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source 33 Service Manual for Speed Oven Model DSO 500 JET PLATES - NOTES 34 COMPONENT OVERVIEW CABINET COOLING FANS • The cabinet cooling fans provide air circulation for cooling the cabinet. Two fans are used to draw air into the cabinet and one fan is used to exhaust the air. Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source Location and Access The three intake and exhaust fans, Figure 14, are located on the rear surface of the oven. Two are located on the right side and one on the left side. The right side panel, top panel and left side panel will need to be removed. To remove the exhaust fan, the chimney needs to be removed. Tools required • Flat blade screwdriver to remove panels and remove fans and fan guards. Operational Testing. The fans are operational whenever the POWER switch is in the ON position and any time the cooling thermostat sees a temperature greater than 40°C. When the POWER switch is turned off but cabinet temperature exceeds 40o C the fans will continue running. Test Procedure Turn on POWER switch and check that all three fans are operating. If one of the fans is not operating check wiring to that fan. Turn off POWER switch and allow cabinet to cool down. If fans do not stop operating thermal switch may be faulty. Replacement Figure 14. Cooling Fans Safety Issues WARNING Unplug oven from power source. Remove top and side covers. Disconnect wires to the defective fan. Remove screws, nuts and grill then remove fan. Install new fan and the grill using the screws and nuts previously removed. Reconnect wires. Install side and top covers. Plug oven into power source and recheck operation. WHEN THE TOP IS REMOVED THE HIGH VOLTAGE CAPACITOR IS EXPOSED. THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 KVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. 35 Service Manual for Speed Oven Model DSO 500 CABINET COOLING FANS - NOTES 36 COMPONENT OVERVIEW MAGNETRON COOLING FANS The magnetron cooling fans, Figure 15, provide air circulation for cooling the magnetrons and high voltage transformer. This is a twin blower fan. Location and Access The magnetron cooling fans are located on the top front of the oven under the top panel. The top panel will need to be removed. Safety Issues WARNING WHEN THE TOP IS REMOVED THE HIGH VOLTAGE CAPACITOR IS EXPOSED. THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source Tools required • Flat blade screwdriver to remove top panel of oven • 3/8 inch nut driver to remove nuts securing fan to top of oven Operational Testing The fan is operational whenever the POWER switch is in the ON position and any time the cooling thermostat sees a temperature greater than 40°C. When the POWER switch is turned off but cabinet temperature exceeds 40°C the fan will continue running. Figure 15. Magnetron Cooling Fans 37 Service Manual for Speed Oven Model DSO 500 Test Procedure Replacement Turn on POWER switch and check that the fan is operating. If the rear panel fans are operation but the magnetron cooling fan is not operating check wiring to that magnetron cooling fan. Turn off POWER switch and allow cabinet to cool down. If magnetron cooling fan does not stop operating thermal switch may be faulty. Unplug oven from power source. Remove top cover. Disconnect wires to the defective fan. Remove nuts then remove fan. Install new fan being sure rubber isolated are on the four mounting holes and attach with the four nuts. Reconnect wires. Install top cover. Plug oven into power source and recheck operation. MAGNETRON COOLING FANS - NOTES 38 COMPONENT OVERVIEW CABINET THERMAL SWITCH The cabinet thermal switch, Figure 16, closes when the cabinet temperature exceeds 40°C. When the POWER switch is set to the OFF position, the thermal switch maintains operating voltage to the cooling fans until the cabinet temperature drops below 40°C. Location and Access The thermal switch is located on the top of the oven. The top panel will need to be removed. Tools required • Flat blade screwdriver to remove side panel • #2 Phillips screwdriver to remove screws securing thermal switch to top side of oven Operational Testing The thermostat closes when a temperature greater than 40°C is present in the cabinet. When the POWER switch is turned OFF, the cabinet should cool down and the thermal switch open when the temperature drops below 40o C. If fans do not stop operating thermal switch is probably faulty. Test Procedure Turn on POWER switch and check that the rear panel fans are operating. Allow cabinet to heat up over 40°C. Turn off POWER switch and allow cabinet to cool down. Check that fans stop operating after cool down. Replacement Unplug oven from power source. Remove right side panel. Disconnect wires to the defective thermal switch. Remove screw attaching thermal switch then remove thermal switch. Install new thermal switch with screw. Reconnect wires. Install side panel. Plug oven into power source and recheck operation. Figure 16. Cabinet Thermal Switch Safety Issues • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source 39 Service Manual for Speed Oven Model DSO 500 COOLING FAN THERMAL SWITCH - NOTES 40 COMPONENT OVERVIEW KEYPAD/CONTROL BOARD The keypad/control board, Figure 17, is programmable for different menus, temperature settings, variable fan speed microwave power connection only, microwave and convection combination and also include some service diagnostics. Menu is selected by the keypad. A display screen provides information for selection of recipes and for editing or inserting new recipes. The display also provides cooking displays, events, door open indication, support telephone number, oven stats screens, and error screens. Location and Access The keypad/control board is located on the right front of the oven. The right side panel will need to be removed. Safety Issues • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source Tools required • Flat blade screwdriver to remove side panel • 5/16 inch nut driver to remove nuts securing keypad/control board to front of oven Operational Testing The keypad/control board controls all functions of the oven and provides status and error information. Refer to the Operator Manual for information of status screens and error messages. Test Procedure Refer to the Operators Manual for information of programming with the Keyboard. Replacement Figure 17. Keypad/Control Board Unplug oven from power source. Remove right side panel. Disconnect wires to the defective Keypad/control Board. Remove screws attaching Keypad/Control Board then remove Keypad/ Control Board from the inside of the front panel. Install new Keypad/Control Board with screws. Reconnect wires. Install side panel. Plug oven into power source and recheck operation. 41 Service Manual for Speed Oven Model DSO 500 KEYPAD/CONTROL BOARD - NOTES 42 COMPONENT OVERVIEW INVERTERS The inverters drive the upper and lower convection blower motors. These inverters must be programmed when first installed. Location and Access The inverters, Figure 18, are located on the right side of the oven and mounted to the inside surface ef the rear panel. The right side panel will need to be removed. Tools required • Flat blade screwdriver to remove side panel • #2 Phillips screwdriver to remove screws securing inverters to right side of oven Operational Testing The inverters drive the upper and lower convection fans. Operation of the inverters is controlled by the control board through wires 71-80. Wires 71 through 75 control the upper blower and wires 76 through 80 control the lower blower. Test Procedure Refer to the detailed test procedure in the TEST PROCEDURE section of this manual. Replacement Unplug oven from power source. Remove right side panel. Disconnect wires to the defective inverter. Remove nuts attaching inverter to panel. Install new inverter with nuts. Reconnect wires. Program inverter in accordance with procedure in APPENDIX A. Install side panel. Plug oven into power source and recheck operation. Figure 18. Inverters Safety Issues • Electrical supply of 208/240 VAC to the control transformer when POWER switch is in ON position • Main POWER switch and fuses have 208/240 VAC present on the input side whenever the oven is connected to the input power source • Inverters are powered when power cord is live 43 Service Manual for Speed Oven Model DSO 500 INVERTERS - NOTES 44 SYSTEM TESTING SYSTEM TESTING POWER OUTPUT MEASUREMENT The Model DSO 500 Speed Oven power output is 1600 Watts for a properly operating oven. NOTE: Do not attempt to perform the following procedure unless the following tools are available. Tools required for microwave Power Output Measurement • 1 Liter glass beaker • Supply of cold water • Thermometer with 0.1 degree increments Procedure The following is an approximate method for power output measurement. NOTE: Power Output is affected by the line voltage under load. For correct Power Output measurement, the line voltage under load must be correct. 1. Fill one glass or plastic container with one litre (1.78 pints) of tap water at about 68ºF/ 20ºC, and measure the water temperature. Use a thermometer with a, 0.1 degree gauge). 2 Place the beaker in the center of the oven cavity. 3 Set Time to 63 seconds and Power to 100% Wait until the oven counter reaches zero. 4 Take the container out immediately and stir the water with a plastic implement then measure the water temperature. 5 Calculate the temperature rise of water in the beaker. The temperature rise of the water should be within the following range: Temperature Rise 70ºF ( 21ºC ) Minimum 75ºF ( 24ºC ) Maximum 6. The actual power output in Watts can be calculated by multiplying the water temperature in Celsius by 70. Temperature Rise (°C) 20 21 22 23 24 Power (W) 1400 1470 1540 1600 1680 MICROWAVE LEAKAGE TEST This requirement must be strictly observed. In addition, the leakage reading must be recorded on the service repair documentation while in the customer’s premises. Check for radiation leakage after servicing. Should the leakage be more than 4mW/cm² Inform Duke Service immediately. After repairing or replacing any radiation safety device, keep a written record for future reference, as required by FDA/DHHS and Health and Welfare Canada regulations. Tools required for microwave leakage test • 600ml glass beaker • Supply of cold water • Microwave leakage meter NOTE: Read and understand the following notes and the procedure, before performing the measurements. Make sure that the survey meter you are using has been calibrated and is suitable for measuring frequencies of 2,450 MHz. Do not exceed meter full scale deflection. Leakage meter should initially be set to the highest scale. Adjust to lower scales to ensure that low readings are measured on the most sensitive range. 45 Service Manual for Speed Oven Model DSO 500 WARNING ON A USED OVEN THE LEAKAGE AROUND DOOR SHOULD NOT EXCEED 4mW/cm². When measuring the leakage, use the probe supplied with the instrument. Always hold the probe at right angles to the oven and point of measurement. Measuring Procedure 1. Move the meter probe at 1”/sec. over all door/oven gaps. 2. Place 275ml of cold water in the 600ml glass beaker. 3. Place the 600ml glass beaker in the center of oven. NOTE: Water must be changed every 30 seconds to prevent boiling. If water boils the results may be inaccurate. 4. Close the door and set time for 30 seconds then press Power pad 100%. 5. Move the meter probe as described in step 1. 46 COMPONENT TESTING COMPONENT TESTING POWER TRANSFORMER TEST WARNING THE HIGH VOLTAGES AND CURRENTS AT THE FILAMENT AND SECONDARY WINDING OF THE TRANSFORMER ARE EXTREMELY DANGEROUS. NEVER MAKE ANY DIRECT VOLTAGE OR CURRENT MEASUREMENTS AT THESE WINDING. IT IS VERY DANGEROUS TO WORK NEAR THIS PART WHEN THE OVEN IS ON, OR IF THIS CIRCUITRY HAS BEEN SWITCHED OFF. WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE PERFORMING THIS PROCEDURE. WAIT AT LEAST FIVE (5) MINUTES AFTER SHUTDOWN OF HIGH VOLTAGE SYSTEM. 2. Discharge the high voltage capacitor as described in the paragraph DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN. 3. Remove all connections from the Power Transformer. 4. Using a digital multimeter, check the resistance of the windings. Results should be as follows: a. Primary Winding Less than 1 ohm b. High Voltage Secondary Winding 65 ohms c. Filament Winding Less than 1 ohm WARNING THE POWER TRANSFORMER HAS HIGH VOLTAGES PRESENT AT ALL TIMES EVEN IF THE OVEN IS NOT COOKING. BE SURE THE OVEN IS ISOLATED BEFORE TESTING. REFER TO THE SAFETY PRECAUTIONS AT THE FRONT OF THIS MANUAL. Tools required • Digital Multimeter (D.M.M.) • Insulation Resistance Tester 5 Using an insulation resistance tester to test the insulation resistance between the following: a. Primary Winding and Chassis Pass if over 10 Mohms b. Filament winding and chassis Pass if over 10 Mohms NOTE: One end of the High Voltage winding is connected to the chassis, therefore it cannot be tested. Procedure 1. Isolate the oven from the power source. 47 Service Manual for Speed Oven Model DSO 500 DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE MODEL DSO 500 Function In common with all microwave cooking appliances, the microwave energy is generated by a magnetron vacuum tube, driven by a high voltage DC power supply, operating at 5000 V. The 208/240 VAC line voltage is stepped up to 2500 VAC by a high voltage transformer and then to a capacitor-diode rectification circuit that functions as a voltage doubler. Location and Access The high voltage system is located above the cook chamber at the top of the cabinet and is composed of two independent electrically identical sets of components. The high voltage wires are thickly insulated and white. They connect all components of each high voltage system, comprising a high voltage transformer, high voltage capacitor, high voltage diode and magnetron. The top and side panels will need to be removed to gain access. Safety Issues The high voltage capacitors retain a lethal charge after the oven is switched off and both capacitors must be electrically discharged prior to any work on the high voltage components and wiring. WARNING THE HIGH VOLTAGE SYSTEM IS POTENTIALLY DANGEROUS EVEN WHEN THE POWER IS OFF. Note that due to the high voltage, it is possible to receive an electric shock when touching a nonmetal part such as an insulated connector or even an insulated cable. Tools Required 48 Approximately 12 inches of high voltage insulated cable of the type used for the high voltage wiring. The conductor should be bared at each end to a length of 0.5 inch. This cable is used to discharge both high voltage capacitors. Insulated needle nose pliers to remove capacitors’ rubber boots. High Voltage Capacitor Four Stage Discharge Procedure. 1. The oven must be switched off and the power cord removed from the power socket. 2. Wait 5 minutes from when the HV system was last powered up. This will permit a partial discharge through the capacitors’ internal safety resistors (if functioning CAUTION). 3. Taking the 12 inch cable, ground one end to the rear panel and then touch the other end to the negative terminal of each high voltage diode in turn. In the event of a large spark, this means that the internal safety resistor in the HV capacitor is faulty. Replace the HV capacitor and clearly mark the defective capacitor to prevent accidental re-use. 4. Carefully remove each rubber boot from the high voltage capacitors using the needle nose pliers. Then using the 12 inch cable, connect both terminals of a HV capacitor together for 5 seconds. Repeat on the remaining HV capacitor. The HV system is now discharged and safe to work on. COMPONENT TESTING HIGH VOLTAGE CAPACITOR TEST WARNING Test Procedure 1. Disconnect the oven from the power source. THE HIGH VOLTAGES AND CURRENTS AT THE FILAMENT AND SECONDARY WINDING OF THE TRANSFORMER ARE EXTREMELY DANGEROUS. NEVER MAKE ANY DIRECT VOLTAGE OR CURRENT MEASUREMENTS AT THESE WINDING. IT IS VERY DANGEROUS TO WORK NEAR THIS PART WHEN THE OVEN IS ON, OR IF THIS CIRCUITRY HAS BEEN SWITCHED OFF. 2. Remove top cover and right side panel to access the high voltage capacitor. WARNING 3. Discharge the high voltage capacitor as described in the paragraph DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN. THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. WARNING THE HIGH VOLTAGE CAPACITOR HAS HIGH VOLTAGES PRESENT AT ALL TIMES EVEN IF THE OVEN IS NOT COOKING. BE SURE THE OVEN IS ISOLATED BEFORE TESTING. REFER TO THE SAFETY PRECAUTIONS AT THE FRONT OF THIS MANUAL. Tools required • Digital Multimeter • Megohmmeter WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE PERFORMING THIS PROCEDURE. WAIT AT LEAST FIVE (5) MINUTES AFTER SHUTDOWN OF HIGH VOLTAGE SYSTEM. 4. Ensure that the High Voltage Capacitor is fully discharged before commencing work. 5. Remove all connections from the High Voltage Capacitor. 6. Using a digital multimeter, check between capacitor terminals & compare results with the following: a. Pass if approximately 10 Megohms: b. Pass if open circuit between terminals and case. 7. Using a Megger, test the insulation resistance between the terminals and the case. Resistance should exceed 100 Megohms. 49 Service Manual for Speed Oven Model DSO 500 HIGH VOLTAGE RECTIFIER TEST WARNING THE HIGH VOLTAGES AND CURRENTS AT THE HIGH VOLTAGE RECTIFIER ARE EXTREMELY DANGEROUS. NEVER MAKE ANY DIRECT VOLTAGE MEASUREMENTS AT THE HIGH VOLTAGE RECTIFIER CIRCUIT. IT IS VERY DANGEROUS TO WORK NEAR THIS PART WHEN THE OVEN IS ON. WARNING THE HIGH VOLTAGE RECTIFIER HAS HIGH VOLTAGES PRESENT AT ALL TIMES EVEN IF THE OVEN IS NOT OPERATING. BE SURE THE OVEN IS ISOLATED BEFORE TESTING. REFER TO THE SAFETY PRECAUTIONS AT THE FRONT OF THIS MANUAL. WARNING THE HIGH VOLTAGE CAPACITOR RETAINS THE 2.5 kVDC CHARGE EVEN AFTER THE OVEN IS DISCONNECTED. THIS CAPACITOR MUST BE DISCHARGED BEFORE WORKING ON ANY COMPONENTS IN THE HIGH VOLTAGE AREA. Tools required • Digital Multimeter • Megohmmeter Test Procedure 1. Disconnect the oven from the power source. 2. Remove top cover and right side panel to access the high voltage diodes (rectifiers). WARNING HIGH VOLTAGE CAPACITOR MUST BE DISCHARGED BEFORE PERFORMING THIS PROCEDURE. WAIT AT LEAST FIVE (5) MINUTES AFTER SHUTDOWN OF HIGH VOLTAGE SYSTEM. 3. Discharge the high voltage capacitor as described in the paragraph DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN. 4. Ensure that the High Voltage Capacitor is fully discharged before commencing work. 5. Remove all connections from the High Voltage rectifier. 6. Using a megohmmeter, test for continuity between rectifier terminals. Reverse megohmmeter leads and check again. Check for the following results: a. S h o r t c i r c u i t i n b o t h d i r e c t i o n s : Replace rectifier b. O p e n c i r c u i t i n b o t h d i r e c t i o n : Replace Rectifier c. Conducts one way and shows leakage the other way: Replace Rectifier d. C o n d u c t s o n e d i r e c t i o n o n l y : Rectifier is good. 50 COMPONENT TESTING MECHANICAL RELAYS AND INTERLOCK SWITCHES Mechanical relays K6, K7 and K8, Figure 19, are part of the door interlock circuit and are activated by door switches “P” (primary), “S” (secondary) and “M” (monitor), Figure 20. with no output contact closure. If no output contact closure is detected at relay K7 check for presence of coil voltage. If coil voltage is not present check for proper activation of door switch “M” (monitor), Figure 19. 5. With the oven door in the “closed” position check for output contact closure at relays K6 and K8. Check that relay K7 is inactive with no output contact closure. If no output contact closure is detected at relays K6 or K8 check for presence of coil voltage. If coil voltage is not present check for proper activation of door switches “P” (primary) for relay K6 and “S” (secondary) for relay K8. 6. If any mechanical relay fails to activate when coil voltage is present, replace the relay. 7. Testing complete. Actuate oven master switch to “off”, powered-down position. 8. Reconnect wires to the relay output contacts of each relay. 9. Reinstall oven right side panel. Figure 19. Mechanical Relays Tools Required • Digital Multimeter (D.M.M.) Procedure 1. Remove oven right side panel to gain access to the mechanical relays. 2. Disconnect and label the wires connected to the relay output contacts of each relay. Leave the coil supply voltage wires connected. 3. Actuate oven master switch to the “on”, powered position. 4. With the oven door in the “open” position check for output contact closure at relay K7. Check that relays K6 and K8 are inactive Figure 20. Door Interlock Switches (Left) 51 Service Manual for Speed Oven Model DSO 500 COMPONENT TESTING - NOTES 52 REPAIR PROCEDURES REPAIR PROCEDURES RELAY AND SWITCH REPLACEMENT General The panel containing the solid state relays, K1 through K5, the primary relay, K6, the secondary relay, K8, and the monitor relay, K7, as shown in Figure 21. 4. Remove the two screws securing the relay to the panel and remove the relay. 5. Be sure replacement relay is oriented properly then attach relay with the two mounting screws. 6. Observe the wire labeling and reconnect the wires to the relay. 7. Reinstall the left side panel. Switch Replacement Procedure 1. Disconnect the oven from the power source. 2. Remove the right side of the oven to access the primary or monitor switches, or remove the left side of the oven to access the secondary or control switches. 3. Disconnect and label the wires attached to the switch to be replaced. 4. Remove the two screws attaching the switch to the switch plate and remove the switch. 5. Be sure replacement switch is oriented properly then attach switch with the two mounting screws. 6. Observe the wire labeling and reconnect the wires to the switch. 7. Refer to the Door Interlock Adjustment Procedure in the ADJUSTMENTS Section. 8. Reinstall the side panel. Figure 21. Solid State and Mechanical Relays 9. Perform the Microwave Leakage Test Procedure in the TEST section. Relay Replacement Procedure 1. Disconnect the oven from the power source. 2. Remove the right side panel to access the relays. 3. Disconnect and label the wires attached to the relay to be replaced. 53 Service Manual for Speed Oven Model DSO 500 LINE FUSE REPLACEMENT General The two line fuses are mounted in a fuse block on the lower left side of the oven as shown in Figure 22. Replacement Procedure WARNING THE FUSE HOLDER WILL REMAIN ALIVE UNLESS THE OVEN IS DISCONNECTED FROM THE POWER SOURCE. 1. Disconnect the oven from the power source. 2. Remove the right side panel to access the fuses. 3. Carefully remove the fuse(s) from the fuse block. 4. Install the replacement fuse(s). 5. Reinstall the right side panel. Figure 22. Solid State and Mechanical Relays NOTE: Both fuses are live if the power cord is plugged into a live socket. Remove power cord from wall socket before attempting to change or test the fuses. 54 REPAIR PROCEDURES INVERTER REPLACEMENT General The two inverters are mounted on the right side of the back panel of the oven as shown in Figure 23. Replacement Procedure 1. Disconnect the oven from the power source. 2. Remove the right side panel to access the inverters. 3. Disconnect and label the wires attached to the terminals on the bottom of the inverter. 4. Remove the nuts securing the inverter to the back panel and remove the inverter. NOTE: New inverters must be programmed after installation 5. Be sure replacement inverter is oriented properly then attach inverter to the back panel with the nuts. 6. Observe the wire labeling and reconnect the wires to the terminals on the bottom of the inverter. 7. Check and enter new program settings, Refer to Appendix A. 8. Reinstall the right side panel. Figure 23. Inverters 55 Service Manual for Speed Oven Model DSO 500 BLOWER MOTOR REPLACEMENT General The upper and lower Blower Motors are located directly behind the oven rear panel and are accessed through the oven left side panel. The “squirrel cage” fan is attached to the motor shaft and can be removed as a complete unit. Replacement Procedure TO BE PROVIDED Figure 24. Figure 25. 56 REPAIR PROCEDURES 57 Service Manual for Speed Oven Model DSO 500 ELECTRICAL PANEL REPLACEMENT 6. Install the new control panel and attach to oven with the mounting screws. General 9. Reinstall the right side panel. 8. Reconnect connectors J1, J2, J3, and J4. The electrical panel is located directly behind the membrane touchpad located on the right front side of the oven. The electrical panel circuit board is accessed through the right side panel of the oven. The control board and touchpad are replaced as a single unit. See Figure 26. Figure 27. Electrical Panel Connectors Figure 26. Control Panel Replacement Procedure 1. Disconnect and isolate the oven from the power source. 2. Remove the right side panel to gain access to the electrical panel. 3. Disconnect connectors J1, J2, J3, and J4, Figure 27, from the circuit board. NOTE: The use of a wrist grounding strap is advised to reduce the risk of circuit board damage from static electricity. 4. Remove the control panel mounting screws located in the approximate corners of the control panel. 5. Carefully remove the control panel. 58 REPAIR PROCEDURES MAGNETRON REPLACEMENT General The Magnetron units, Figure 28, are located under the oven top panel on the left and right sides. The right side magnetron unit is nested within a cooling duct. WARNING WHEN TOP COVER IS REMOVED, HIGH VOLTAGES ARE PRESENT. THE HIGH VOLTAGE CAPACITORS MUST BE DISCHARGED BEFORE PERFORMING ANY WORK ASSOCIATED WITH THE MAGNETRON CIRCUITRY. . WAIT AT LEAST FIVE (5) MINUTES AFTER SHUTDOWN OF HIGH VOLTAGE SYSTEM. 3. Discharge the high voltage capacitor as described in the paragraph DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN. 4. Remove cooling duct. (Right side magnetron only). 5. Unplug spade connectors from the terminal housing. 6. Remove magnetron mounting nuts and remove magnetron. CAUTION: When installing the new magnetron, be sure metal mesh gasket is properly positioned around the magnetron dipole antenna. 7. Orient and install the replacement magnetron unit. 8. Replace and secure all mounting nuts. Figure 28. Magnetron Replacement Procedure 1. Disconnect and isolate the oven from the power source. 2. Remove the oven top panel to gain access to magnetrons. 9. Securely reattach the spade connectors to terminals F and FA. Wire 91-1 or 92-1 connect to terminal FA. Wire 91-6 or 92-6 connect to terminal F. 10. Reinstall cooling duct. (Right side magnetron only). 11. Reinstall the oven top panel. 59 Service Manual for Speed Oven Model DSO 500 STIRRER MOTOR REPLACEMENT Replacement Procedure General 1. Disconnect and isolate the oven from the power source. The Stirrer Motor, Figure 29, is located under the oven top panel in the approximate center of the oven and directly in front of the magnetron transformers. WARNING WHEN TOP COVER IS REMOVED, HIGH VOLTAGES ARE PRESENT EVEN WITH THE OVEN DISCONNECTED. 2. Remove the oven top panel to gain access to the stirrer motor. 3. Unplug and label the spade connectors from the terminals. 4. Open oven door and remove top jet plate to access stirrer. 6. Remove mounting screws and remove stirrer motor unit. 7. Orient and install the replacement stirrer motor unit, rotating the stirrer blade until the drive head of the stirrer motor unit engages with the slot in the stirrer shaft. 8. Replace and secure all mounting hardware. 9. Reinstall the spade connectors. 10. Power up the oven to test stirrer motor. 11. Refit top jet plate. 12. Reinstall the oven top panel. Figure 29. Stirrer Motor 60 REPAIR PROCEDURES HEATER ELEMENT REPLACEMENT 1. Disconnect and isolate the oven from the power source. 2. Remove the oven top panel. 3. Remove the oven right and left panels. 4. Loosen the remaining lower central bolt on the rear panel. 5. Remove the two Philips head screws securing back panel to heater cover panel. 6. Allow rear panel to tilt rearwards and secure with a short length of wire or long cable tie. The lower edge remains located by the loosened lower central bolt. 7. Remove wires to heaters using a pair of thin 3/8 inch open ended wrenches. Figure 30. Heater Assembly 8. Remove nine Philips head screws securing the heater insulation outer panel and remove panel. 9. Remove thermal insulation material and secure against loss or damage. 10. Remove ten Phillips head screws securing heater assembly to oven. NOTE: Take care when removing these screws. After extended service, some of these may bind. If resistance is encountered. A drop of WD-40 or similar oil is highly effective if allowed several minutes to penetrate into the threads. 11. Remove heater assembly, Figure 30. 12. Fit new 1700 W heat coil. 13. Reassemble by Reversing the procedures. 61 Service Manual for Speed Oven Model DSO 500 CABINET THERMAL SWITCH REPLACEMENT Replacement Procedure General 2. Remove the oven top panel to gain access to the thermal switch. The cabinet thermal switch is located on top of the oven, behind the oven top panel. The thermal switch, shown in Figure 31, will close and operate the twin cooling fan and three rear panel mounted fans anytime the oven cabinet temperature is above 40°C. The cooling fans will function independent of the MASTER ON/OFF switch setting. 1. Disconnect and isolate the oven from the power source. 3. Unplug and label the spade connectors from the thermal switch. 4. Remove thermal switch mounting screws and remove thermal switch. 5. Orient and install the replacement thermal switch. 6. Replace and secure all mounting screws. 7. Securely reattach the spade connectors. 8. Reinstall the oven top panel. Figure 31. Cabinet Thermal Switch 62 REPAIR PROCEDURES HIGH VOLTAGE TRANSFORMER REPLACEMENT General The high voltage transformers, Figure 32, are located directly under the oven top panel at left and right center. The transformers work in conjunction with two high-voltage capacitors and rectifiers located directly behind each transformer. Replacement Procedure 1. Disconnect and isolate the oven from the power source. 2. Remove the oven top panel to gain access to the magnetron transformers and capacitors. WARNING THE HIGH VOLTAGE CAPACITORS MUST BE DISCHARGED BEFORE PERFORMING ANY WORK ASSOCIATED WITH THE TRANSFORMER CIRCUITRY. WAIT AT LEAST FIVE (5) MINUTES AFTER SHUTDOWN OF HIGH VOLTAGE SYSTEM. 3. Discharge the high voltage capacitor as described in the paragraph DISCHARGING THE HIGH VOLTAGE SYSTEM ON THE DUKE SPEED OVEN. 4. Unplug and label all spade connectors from the transformer. 5. Note orientation of transformer, then remove transformer mounting screws and remove transformer unit. 6. Orient and install the replacement transformer unit. 7. Replace and secure all mounting screws. 8. Securely reattach the spade connectors. 9. Reinstall the oven top panel. Figure 32. High Voltage Transformer 63 Service Manual for Speed Oven Model DSO 500 FRONT THERMAL COOLING FAN REPLACEMENT Replacement Procedure General 2. Remove the oven top panel to gain access to the thermal cooling fan motor and “squirrel cage” fans. The front thermal cooling fan, Figure 33, is located directly behind the top, front panel of the oven and is accessed through the oven top panel. The thermal cooling unit consists of a double shaft end motor with a “squirrel cage” fan unit attached to each motor shaft. The thermal cooling fan will operate anytime the oven cabinet temperature is above 40°C. The thermal cooling fan will function independent of the MASTER ON/OFF switch setting. This fan cools the magnetrons, high voltage transformers, and door switches. 1. Disconnect and isolate the oven from the power source. 3. Remove all metal ducting and shrouds. 4. Disconnect and label all wiring to the thermal cooling fan motor. 5. Remove motor mounting screws and nuts and remove the motor and “squirrel cage” fans as a complete assembly. 6. Install the new thermal cooling fan unit and replace and secure all mounting hardware. Be sure the rubber grommets are in place. 9. Reconnect all wiring to the thermal cooling fan motor. 10. Reinstall all metal ducting and shrouds. 11. Reinstall the oven top panel. Figure 33. Front Thermal Cooling Fan 64 REPAIR PROCEDURES INTAKE AND EXHAUST FANS REPLACEMENT Replacement Procedure General NOTE: The three fans are attached to the back panel. When removing back panel take care not to break any wires attached to the fans. The two intake fans and the one exhaust fan, Figure 34, are located on the back of the unit. 1. Disconnect and isolate the oven from the power source. 2. Remove the oven rear panel to gain access to the fans. 3. Disconnect wires from the fan to be serviced. 4. Remove the attaching hardware, then remove the fan and the grill. 5. When installing a new fan, be sure to also install the grill on the outside of the back panel. Figure 34. Cabinet Cooling Fans 65 Service Manual for Speed Oven Model DSO 500 ADJUSTMENTS Door Interlock Adjustment The Speed Oven will not operate unless the interlock switches, Figure 35 and Figure 36, are properly engaged. Make no attempt to mechanically or electrically override the interlock circuit. When the door is latched closed, the interlock switches “P” and “S” must be engaged (contacts closed) and the monitor switch “M” must be disengaged (Contacts open). When the oven door is open, the interlock switches “P” and “S” must be disengaged (contacts open) and the monitor switch “M” must be engaged (Contacts closed). Tools Required • Open end wrench • Crescent wrench Procedure Figure 35. Door Interlock Switches (Left) 1. Disconnect the oven from the power source. 2. Remove oven left and right side panels to gain access to the interlock switch assembly. (Switches are located at the top corners at the point where oven door latches engage). 3. Locate the adjustment bolt. 4. Loosen the locking nut and adjust the switch plate to mechanically engage the primary interlock switch “P” and the secondary interlock switch “S”. At this time the monitor switch “M” and the control switch must be disengaged. 5. Repeat this procedure on opposite side. NOTE: Both interlock switches “P” and “S” must fully engage for oven to operate. 6. Perform the Microwave Leakage Test Procedure in the TEST section. NOTE: Be aware of wiring differences between control switch and monitor switch. 66 Figure 36. Door Interlock Switches (Right) TROUBLESHOOTING TROUBLESHOOTING Error Codes INFORMATION TO BE PROVIDED Figure Error Code Displays Troubleshooting Table The troubleshooting table provides a list of Symptoms in the left-hand column. The center column lists the probable causes for the indicated Symptom. The right-hand column provides procedures to remedy the Symptom. TROUBLESHOOTING TABLE SYMPTOM Oven will not operate(Magnetrons) POSSIBLE CAUSE Incoming power supply. REMEDY Check all electrical connections. Check master switch. Check for power at wall receptacle. Check main fuse block. Oven door improperly closed. Insure that oven door is fully closed and latched. Check for interference. Check door seal. Door interlock switches. Inspect door latch switches (4) to insure that the switches are mechanically actuating when door is closed and adjust if necessary. Insure L1 output from switch “P” and “S” and no output from switch “M” with door in closed position. At the electronic control board, check for closed circuit at J1 terminals 8 and 9. Door interlock circuit mechanical relays With oven door in the closed position check for supply voltage at the coil terminals of relays K6 and K8. If supply voltage is not present trace wiring back through door switches and master switch. If supply voltage is present check for output voltage at relays K6 and K8. If output voltage is not present replace the defective mechanical relay. 67 Service Manual for Speed Oven Model DSO 500 SYMPTOM POSSIBLE CAUSE Solid State Relays Magnetron Transformer Oven will not operate (Convection) Solid State Relays REMEDY Check for 12 VAC supply voltage to solid state relays K4 and K5. If present check for L2 voltage at terminal L1. If L2 voltage is present check for L2 output at terminal T1. If no output voltage is present replace defective solid state relay. Check for 208/220-240 VAC supply voltage to the transformer primary terminals. If no voltage is present isolate and check the high limit thermostat. If circuit is closed trace wiring back to the master switch. If circuit is open while oven is in the off state, replace the thermostat. If supply voltage is present check for voltage of min. 4000VAC at magnetron terminals F and FA. If voltage is present replace magnetron. Check for 12 VAC supply voltage to solid state relays K1, K2 and K3. If present check for L2 voltage at terminal L1. If L2 voltage is present check for L2 output at terminal T1. If no output voltage is present replace defective solid state relay. High Limit Thermostat Isolate and check the high limit thermostat. If circuit is open while oven is in off state, replace the thermostat. Auxiliary Thermostat Isolate and check the auxiliary thermostat. If circuit is open while oven is in off state, replace the thermostat. Heating Elements Check for 208/220-240 VAC supply voltage to the heating elements. If voltage is present and heating elements are inoperable, replace heating elements. Check current draw of magnetron 68 TROUBLESHOOTING SYMPTOM POSSIBLE CAUSE Magnetrons operate intermittently Current sensors detect overload state Stirrer motor will not operate Stirrer Motor REMEDY unit(s). If current is above normal operating specs, replace magnetron unit(s). If magnetrons are operating check stirrer motor wire connections and confirm that supply voltage is present at stirrer motor terminals. If supply voltage is present replace stirrer motor. Note: Stirrer motor stops when door is open. Mechanical Relay PrimaryK6 Convection blower motors will not operate Inverter Drive Electronic Control Board Wiring harness Blower Motor If magnetrons are not working refer to “Oven will not operate (Magnetrons)” and use the “Door interlock circuit mechanical relays” instructions. Check for supply voltage at the L1 and L2 terminals on the inverter. If supply voltage is not present trace wiring back to source to insure proper connection. If supply voltage is present check output voltage to blower motor at terminals T1, T2 and T3. If output voltage is not present check for incoming control signals at terminals 3, 5, 8, 9 and 10. If control signals are not present trace and check wiring back to the electronic control board. Check for control output signals at terminals 1 thru 10 of the upper and lower blower units. If no signals are present replace the electronic control board. If output voltage is present at inverter terminals T1, T2 and T3 insure that same voltage is present at motor electrical connections. If output voltage is not present, replace the wiring harness. If inverter output voltage is present at the motor electrical connections and motor does not operate, replace the blower motor. 69 Service Manual for Speed Oven Model DSO 500 SYMPTOM Electronic control board inoperative POSSIBLE CAUSE Control Transformer Check for 208/220-240 VAC supply voltage to the transformer primary terminals. If no voltage is present trace the wiring back through the master switch and check all connections. If supply voltage is present check for voltage of 12 VAC at transformer secondary terminals. If no voltage is present at transformer secondary terminals, replace transformer. Electronic Control Board Check for incoming 12 VAC to J1 terminals 4 and 5. If voltage is present, replace electronic control board. Cooling motor will not oper- Cooling Thermostat ate Cooling fan(s) inoperative 70 REMEDY Check that cooling thermostat circuit is closed when oven temperature is above 40°C. If circuit is open replace the cooling thermostat. Cooling Motor Check for 208/220-240 VAC supply voltage to the motor electrical connections. If voltage is present at motor with no operation, replace motor. Cooling Fan Motor Check for 208/220-240 VAC supply voltage to the motor electrical connections. If no voltage is present trace the wiring back through the master switch and check all connections. If voltage is present at motor with no operation, replace motor. SCHEMATICS Figure 11. Schematic Diagram 71 Service Manual for Speed Oven Model DSO 500 SPARE PARTS LIST This list details most of the replacement parts required for service the oven. PART NUMBER PART NUMBER Magnetron & Thermal Switch 168100 High Voltage Transformer 167503 High Voltage Diode 167504 High Voltage Capacitor 167591 Main Line Fuse 168120 Stirrer Motor/Gearbox 168072 Rear Muffin Fan 167548 Magnetron Twin Cooling Fan 167601 Cabinet Cool Down Thermostat, 40°C. 167654 Control Panel, Complete 168033 Solid State Relay ( SSR ) 167508 Mechanical Relay 167509 Monitor & Computer, Door Switch, no Actuator 168086 Primary & Secondary, Door Switch, with Actuator 168013 Door Switch Insulator 167951 RTD Probe 167610 12 VAC Transformer 155749 Heater 1000 W 167586 Heater 1700 W 167964 “O”, Left, High Limit Thermal Cutout, 575°F 167656 “I”, Right, Aux Thermostat 525°F ( near RTD ) 167655 Inverter, Blower Motor 167603 Main Power Switch 156527 72 APPENDIX A APPENDIX A INVERTER PROGRAMMING The following procedure must be used to program the inverters. The inverter must be installed in the oven before proceeding with programming. 6. After confirmation of last parameter, change mode back to “Run” mode until green LED “FREF” is illuminated. PROGRAMMING PROCEDURE 7. Disconnect oven from power source,and allow inverter capacitors to discharge completely. The inverter must be installed in a fully assembled oven before programming. CAUTION: Do not touch any components except as mentioned in procedure. 1. Switch oven POWER switch to OFF position. Disconnect oven from power source and allow inverter capacitors to discharge completely. 8. To verify settings, plug oven into power source. Verify that inverters display no error, then switch power switch to ON position. Inverters should drive convection blowers at approximately 30 Hz when the oven door is closed. Motor does not run when door is open. 9. Switch power off, disconnect oven from power. (Inverter capacitors fully discharged) then remount right panel. 2. Remove right side panel to access inverters. 3. Connect oven to power source to power inverters. Oven POWER switch must remain in the OFF position. 4. Change inverter from running into programming mode by pressing blue menu button on inverter, i.e. until red LED “PRGM” is illuminated. The screen will display “n01” as the first parameter to be set. 5. The parameter as listed in the table at the end of this procedure. Access parameters to be set by pressing the “arrow up” or “arrow down” keys. Access parameter value by pressing yellow “carriage return” key. The parameter can now be edited. Change parameter value with the “arrow up” or “arrow down” keys. Confirm setting with “carriage return” key. Repeat as need, until all required parameters have been adjusted. NOTE: When accessing parameters n36 to n39, parameter n39 has to be changed first before n36 to n38, otherwise an error message will be displayed. 73 Service Manual for Speed Oven Model DSO 500 INVERTER SETTINGS PARAMETER NAME n01 Parameter to access/access prohibition of parameters to be edited 1 1 All parameters can be monitored/edited. n02 Operation mode selection 1 1 Multi function inputs at control circuit terminals enabled. n03 Frequency reference selection 2 2 Input at frequency reference control terminals (0-10V) n04 Interruption mode selection 0 0 Decelerate in present time n05 Reverse rotation enabled/prohibit 0 0 Reverse rotation enabled n06 Stop/reset function key selection 0 0 Stop reset of operator enabled n07 Frequency selection in local mode 0 0 Frequency adjustor of digital operator enabled n08 Key sequential frequency setting 0 0 Enter to confirm input value n09 Maximum frequency 60 Hz 60 Hz Maximum speed setting for motor n10 Maximum voltage 230V 230V Maximum motor supply voltage n11 Maximum voltage frequency 60 Hz 60 Hz Maximum speed setting for motor at highest supply voltage n12 Middle output frequency 1.5 Hz 1.5 Hz Defined middle operating speed of motor n13 Middle output frequency range 12V 12V Defined middle operating supply voltage of motor n14 Minimum output frequency 1.5 Hz 1.5 Hz Lowest operating speed of motor n15 Minimum output frequency voltage 12V 12V Lowest operating supply voltage of motor 74 SETTING DEFAULT REMARKS APPENDIX A INVERTER SETTINGS (Cont.) PARAMETER NAME SETTING DEFAULT REMARKS n16 Acceleration time 1 0.6s 1s Acceleration from 0% to 100% speed n17 Acceleration time 1 0.6s 1s Acceleration from 0% to 100% speed n18 Acceleration time 2 0.6s 1s Acceleration from 0% to 100% speed in conjunction with speed references n19 Acceleration time 2 0.6s 1s Acceleration from 0% to 100% speed in conjunction with speed referenced n20 S-shape acceleration/deceleration characteristics 1 0 S-shape acceleration/deceleration 0.2s characteristics (to prevent motor damage due to shock) n21 Frequency reference 1 15 Hz 6 Hz Multi-step speed reference for motor n22 Frequency reference 2 30 Hz 0 Hz Multi-step speed reference for motor n23 Frequency reference 3 60 Hz 0 Hz Multi-step speed reference for motor n24 Frequency reference 4 0 Hz 0 Hz Multi-step speed reference for motor n25 Frequency reference 5 0 Hz 0 Hz Multi-step speed reference for motor n26 Frequency reference 6 0 Hz 0 Hz Multi-step speed reference for motor n27 Frequency reference 7 0 Hz 0 Hz Multi-step speed reference for motor n28 Frequency reference 8 0 Hz 0 Hz Multi-step speed reference for motor 75 Service Manual for Speed Oven Model DSO 500 INVERTER SETTINGS (Cont.) PARAMETER NAME n29 Frequency inching command 6 Hz 6 Hz Multi-step operation to allow operation at discrete frequency steps n30 Frequency reference upper limit 100% 100% Determines max upper frequency reference n31 Frequency reference lower limit 0% 0% Determines max lower frequency reference n32 Rated motor current 0.6A 0.6A Program rated motor current for overload detection n33 Motor Protection characteristics 0 0 n34 Motor protective time setting 8min 8min Sets time for overload protection n35 Cooling fan operating settings 0 0 Set time for overload protection n36 Multi-function input 1 setting (S2) 6 2 Setting multi-step speed reference 1 n37 Multi-function input 2 setting (S3) 7 5 Setting multi-step speed reference 2 n38 Multi-function input 3 setting (S4) 8 3 Setting multi-step speed reference 3 n39 Multi-function input 4 setting (S5) 35 6 Setting self test n40 Multi-function output MA/ MB/MC 1 1 Setting operation in process n41 Frequency reference gain 100% 100% n42 Frequency reference bias 0% 0% 76 SETTING DEFAULT REMARKS Protection setting for general purpose motors Frequency of maximum analog input in percentage of maximum input frequency Frequency of minimum analog input in percentage input frequency APPENDIX A INVERTER SETTINGS (Cont.) PARAMETER NAME n43 Analog frequency reference time n44 SETTING DEFAULT REMARKS 0.1s 0.1s Digital filter with first-order lag for analog reference frequencies Analog monitor output 0 0 Setting of output frequency to be monitored n45 Analog output monitor gain 1 1 Set the characteristics of monitored output signal n46 Carrier frequency selection 1 4 Set to 2.5 kHz to minimize leakage current n47 Momentary power interruption compensation 2 0 Inverter restarts after power restored n48 Fault retry 0 0 Set times how often inverter is reset and restarted after overvoltage, overcurrent or ground fault n49 Jump frequency 1 0Hz 0Hz Enables and sets frequency jump function n50 Jump frequency 2 0Hz 0Hz Enables and sets frequency jump function n51 Jump width 0Hz 0Hz Determine jump width from center frequency n52 DC control current 50% 50% Sets imposed DC braking current on induction motors for braking control in percent of rated current n53 Interruption DC control time 0s 0s Defines braking time n54 Startup DC control time 0s 0s Defines deceleration time at startup n55 Stall prevention level during acceleration 0 0 Stall prevention during 77 Service Manual for Speed Oven Model DSO 500 INVERTER SETTINGS (Cont.) PARAMETER 78 NAME SETTING DEFAULT REMARKS n56 Stall prevention level during acceleration 170% 170% Deceleration enabled Automatically stops acceleration for stall prevention during acceleration by set level of percentage on rated current of inverter at 100% n57 Stall prevention during operation 160% 160% Automatically reduces frequency for stall prevention during acceleration by set level of percentage on rated current of inverter at 100% n58 Frequency detection level 0Hz 0Hz Set frequency to be detected during operation n59 Overtorque detection function selection 0 0 Setting overtorque detection disabled n60 Overtorque detection level 160% 160% n61 Overtorque detection time 0.1s 0.1s n62 Up/down frequency command memory 0 0 Setting frequency not stored n63 Torque compensation gain 1 1 Sets gain of torque compensation function n64 Motor rated slip 2.9Hz 2.9Hz Set slip value of motor n65 Motor no-load current 62% 62% n66 Slip compensation gain 0 0 Set slip compensation gain n67 Slip compensation time constant 2s 2s Set time to compensate for motor slip Set overtorque detection level by setting level in percentage of rated current of inverters Sets detection time of overtorque Set current for motor running without load in percent of rated motor current APPENDIX A INVERTER SETTINGS (Cont.) PARAMETER NAME SETTING DEFAULT REMARKS n68 OMRON reference - 0 Not to be changed under normal programming n69 OMRON reference - 0 Not to be changed under normal programming n70 OMRON reference - 0 Not to be changed under normal programming n71 OMRON reference - 2 Not to be changed under normal programming n72 OMRON reference - 2 Not to be changed under normal programming n73 OMRON reference - 10 Not to be changed under normal programming n74 OMRON reference - 0 Not to be changed under normal programming n75 Low speed carrier frequency reduction selection - 0 Enables reduction of carrier frequency when operating motor at low speed n76 OMRON reference - rdy Not to be changed under normal programming n77 OMRON reference - 0 Not to be changed under normal programming n78 Error log Displays latest error code n79 Software number Displays software number Legend Modified to DSO requirements OMRON reference-not to be adjusted monitor only 79 Duke Manufacturing Company 2305 N. Broadway St. Louis, MO 63102 Phone: 314-231-1130 Toll Free: 1-800-735-3853 Fax: 314-231-5074 www.dukemfg.com