SERVICE MANUAL MICROWAVE OVENS Microwave Oven © ELECTROLUX HOME PRODUCTS Corso Lino Zanussi,30 I - 33080 PORCIA /PN (ITALY) Tel +39 0434 394850 Fax +39 0434 394096 SOI Publication No. GRILL AND CONVECTION MICROWAVE OVEN 599 37 42-75 (Micromat Combi) EN/SERVICE/FV MCC4060E MO940CXE EMC4090X ZM40STX ZM40STN Edition: 12.2006 SOI 12.
SOI 12.
TABLE OF CONTENTS CAUTION, MICROWAVE RADIATION....................................................................................................4 SERVICING / GENERAL INFORMATION ..............................................................................................5 PRODUCT SPECIFICATIONS ................................................................................................................6 APPEARANCE VIEW ..................................................................................
CAUTION CAUTION MICROWAVE RADIATION DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS THAT CONDUCT MICROWAVE ENERGY. GENERAL IMPORTANT INFORMATIONS This Manual has been prepared to provide Service Engineers with Operation and Service Information. It is recommended that service engineers carefully study the entire text of this manual, so they will be qualified to render satisfactory customer service. WARNING Note: The parts marked "*" are used at voltage more than 250V.
SERVICING WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the following parts will result in electrocution High voltage capacitor, High Voltage transformer, Magnetron, High voltage rectifier assembly, High voltage wires. REMEMBER TO CHECK 3D REMEMBER TO CHECK 4R 1) Disconnect the supply. 2) Door opened, and wedged open. 3) Discharge high voltage capacitor.
PRODUCT SPECIFICATIONS SPECIFICATION ITEM DESCRIPTION Power Requirements Power Consumption 230 Volts / 50 Hertz / Single phase, 3 wire earthed Microwave cooking Convection cooking Grill cooking Dual cooking Power Output Grill heating element Power Output Convection heating element Power Output Case Dimensions Cooking Cavity Dimensions Turntable diameter Control Complement 1.5kW Approx. 6.7A 2.7kW Approx.12A 2.7kW Approx.12A Micro and Grill ................... 2.8 kW Micro and Convection ........ 2.
APPEARANCE VIEW OVEN 1. Fixing points (4 points) 2. Grill heating element 3. Convection heating element 4. Oven lamp 5. Control panel 6. Shelf runners 7. Waveguide cover 8. Oven cavity 9. Coupling 10. Door seals and sealing surfaces. 11. Door opening handle 12. Air-vent / intake opening 13. Outer cover 14. Power cord 15. Power supply cord support clip. U.K . BACK VIEW EUROPEAN BACK VIEW 16. Turntable 17. Turntable support 18. High Rack 19. Low Rack 20. Square shelf 21. Square tray SOI 12.
CONTROL PANEL MCC4090E Digital display and indicators: 1. 2. 3. 4. 5. 6. COOKING indicator START indicator GRILL indicator CONVECTION indicator MICROWAVE indicator INFORMATION indicator Operating keys: 7. INFORMATION button 8. LANGUAGE button 9. COOKING MODE knob for microwave cooking for microwave cooking with GRILL for microwave cooking with CONVECTION for GRILL for CONVECTION 10. TIME/WEIGHT knob rotate the knob to enter either the cooking/defrosting time or weight of food. 11. AUTO COOK button 12.
CONTROL PANEL EMC4090X Digital display and indicators: 1. 2. 3. 4. 5. 6. COOKING indicator START indicator GRILL indicator CONVECTION indicator MICROWAVE indicator INFORMATION indicator Operating keys: 7. INFORMATION button 8. LANGUAGE button 9. COOKING MODE knob for microwave cooking for microwave cooking with GRILL for microwave cooking with CONVECTION for GRILL for CONVECTION 10. TIME/WEIGHT knob rotate the knob to enter either the cooking/defrosting time or weight of food. 11. AUTO COOK button 12.
CONTROL PANEL MO040CXE ZM4060STX ZM4090X ZM4090STN Digital display and indicators: 1. 2. 3. 4. 5. 6. COOKING indicator START indicator GRILL indicator CONVECTION indicator MICROWAVE indicator INFORMATION indicator Operating keys: 7. INFORMATION button 8. LANGUAGE button 9. COOKING MODE knob for microwave cooking for microwave cooking with GRILL for microwave cooking with CONVECTION for GRILL for CONVECTION 10. TIME/WEIGHT knob rotate the knob to enter either the cooking/defrosting time or weight of food.
OPERATION SEQUENCE OFF CONDITION Closing the door activates the monitored latch switch and the stop switch. IMPORTANT When the oven door is closed, the contacts COM - NC of the monitored switch must be open. When the microwave oven is plugged in a wall outlet (230V / 50Hz), the line voltage is supplied to the noise filter. ( Figure O-1 ) 1. The control unit is not energized. The display shows nothing (Fig. O-1 (a)). 2. Open the door.
OPERATION SEQUENCE The circuit to the turntable motor is cut off when the contacts (COM-NO) of the monitored latch switch SW1 are made open. The oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted, because the relay RY1 stays closed. Shown in the display is the remaining time. 6. MONITOR SWITCH CIRCUIT The monitor switch SW3 is mechanically controlled by oven door, and monitors the operation of the monitored latch switch SW1.
OPERATION SEQUENCE PRE-HEATING (by 160°C - 250°C) Turn select knob to CONVECTION Programme the desired convection temperature of 160°C - 250°C by pressing the CONVECTION button. When the START button is pressed, the following operations occur: 1. The relays RY1, RY6 and RY7 are energized, the oven lamp, turntable motor, fan motor and convection motor are turned on. 2.
OPERATION SEQUENCE ON/OFF TIME RATIO NOTE: In dual cooking, the magnetron operate within a 48 second time base. The following table is the ON / OFF time ratio at each power output of the magnetron. 1. If the multiple sequence cooking is carried out in same mode, the basis cooking time is calculated from the first. 2. Even if the cooking is stopped by the STOP button or opening the door, the basis cooking time is calculated from the first. 3.
FUNCTION OF IMPORTANT COMPONENTS 3. If the door is opened and the monitored latch switch SW1 contacts (COM-NO) fail to open, the fuse F2 F8A blows immediately after closing of the monitor switch SW3 (COM-NC) contacts. CAUTION: BEFORE REPLACING A BLOWN FUSE SWITCH SW3 FOR PROPER OPERATION. (REFER TO CHAPTER “TEST PROCEDURE”). DOOR OPEN MECHANISM The door can be opened by pulling the door handle.
FUNCTION OF IMPORTANT COMPONENTS THERMAL CUT-OUT TC3 170°C (CONV.) FAN MOTOR FM This thermal cut-out protects the convection motor against overheating. If the temperature of the thermal cut-out TC3 rises above 170°C because the convection fan is interrupted, the ventilation openings are obstructed or the other abnormal matter occurs, the thermal cut-out opens and switches off the convection heating element and the other electrical parts.
FUNCTION OF IMPORTANT COMPONENTS Door Oven Cavity Grill Heating Elements DAMPER OPEN-CLOSE MECHANISM Convection Passage Convection Heating Element Cooling Fan Turntable Roller Stay Turntable Motor Convection Motor Convection Fan Microwave Cooking: Damper is in the open position, because a portion of cooling air is channelled through the cavity to remove steam and vapours given off from the heating foods. It is then exhausted at the top of the oven cavity into a condensation compartment.
FUNCTION OF IMPORTANT COMPONENTS 4. Operation of damper is shown below.
SOI 12.06 FV ● 19/43 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Grill heating element does not heat. ● Oven goes into cook cycle but shuts down before end of cooking cycle. Oven sems to be operative but little or no heat is produced in oven load.
TEST PROCEDURES PROCEDURE LETTER A COMPONENT TEST MAGNETRON TEST NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE THE OVEN IS IN OPERATION. CARRY OUT 3D CHECK Isolate the magnetron from high voltage circuit by removing all leads connected to the filament terminal. To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron filament terminals, the meter should show a reading of less than 1 ohm.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Measuring method: 1. Measure the initial temperature of the water before the water is added to the vessel. (Example: The initial temperature T1 = 11°C) 2. Add the 1 litre water to the vessel. 3. Place the load on the centre of the shelf. 4. Operate the microwave oven at HIGH for the temperature of the water rises by a value ΔT of (10 ± 2) K. 5. Stir the water to equalize temperature throughout the vessel. 6. Measure the final water temperature.
TEST PROCEDURES PROCEDURE LETTER C COMPONENT TEST HIGH VOLTAGE RECTIFIER TEST CARRY OUT 3D CHECKS. Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading. The normal resistance is infinite in one direction and more than 100 kΩ in the other direction.
TEST PROCEDURES PROCEDURE LETTER E COMPONENT TEST SWITCH TEST CARRY OUT 3D CHECKS. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table. Table: Terminal Connection of Switch Plunger Operation COM to NO COM to NC COM; Common terminal Released Open circuit Short circuit NO; Normally open terminal Depressed Short circuit Open Circuit NC; Normally close terminal If incorrect readings are obtained, replace the switch.
TEST PROCEDURES PROCEDURE LETTER H COMPONENT TEST MOTOR WINDING TEST CARRY OUT 3D CHECKS. Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals as described in the table below. Table: Resistance of Motor Motors Resistance Approximately 293 Ω Approximately 12.6 kΩ Approximately 220 Ω Approximately 11 kΩ Fan motor Turntable motor Convection fan motor Damper motor If incorrect readings are obtained, replace the motor. CARRY OUT 4R CHECKS.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 3. If the fuse F2 F8A is blown, there could be shorts in the asymmetric rectifier or there is a ground in wire harness. A short in the asymmetric rectifier may be occurred due to short or ground in H.V. rectifier, magnetron, high voltage transformer or H.V. wire. Check them and replace the defective parts or repair the wire harness. CARRY OUT 4R CHECKS CAUTION: Only replace fuse F2 F8A with the correct value replacement.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 2. Control Panel The following symptoms indicate a defective control unit. Before replace the control unit, perform the Jog and Switch unit test (Procedure N) to determine if control unit is faulty. 2-1.In connection with buttons. a) When touching the buttons, a certain group of buttons do not produce a signal. b) When touching the buttons, no buttons produce a signal. 2-2.In connection with indicators.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST DC. voltage indicated .......... Defective relay. DC. voltage not indicated .... Check diode which is connected to the relay coil. If diode is good, control unit is defective. RELAY SYMBOL RY1 OPERATIONAL VOLTAGE Approx.18.0 V D.C. CONNECTED COMPONENT Oven lamp / Turntable motor RY2 Approx.18.0 V D.C. High voltage transformer RY3 Approx. 24.0 V D.C. Grill (Top) heating element RY4 Approx. 24.0 V D.C. Convection heating element RY5 Approx. 24.
JOG CONTROL PANEL ASSEMBLY OUTLINE OF JOG CONTROL PANEL The jog control section consists of the following units: 4) ACL A circuit to generate a signal which resets the LSI to the initial state when power is supplied. (1) Key Unit (2) Control Unit (The Control unit consists of Power unit and CPU unit.) 5) Buzzer Circuit The buzzer is responsive to signals from the LSI to emit audible sounds (key touch sound and completion sound).
SIGNALS AND TIMES FROM LSI Signal to sound buzzer A: Tact switch touch sound. B: Completion sound. C: When the temperature of the oven cavity reaches the preset temperature in the preheating mode, or when the preheating hold time (30 minutes) is elapsed. Magnetron high-voltage circuit driving signal. To turn on and off the cook relay (RY2). In 100% operation, the signals hold "L" level during microwave cooking and "H" level while not cooking.
SERVICING 1. Precautions for Handling Electronic Components This unit uses CMOS LSI in the integral part of the circuits. When handling these parts, the following precautions should be strictly followed. CMOS LSI have extremely high impedance at its input and output terminals. For this reason, it is easily influenced by the surrounding high voltage power source, static electricity charge in clothes, etc. and sometimes it is not fully protected by the built-in protection circuit.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven. 1. Disconnect oven from power supply. 2. Make sure that a definite "click" can be heard when the microwave oven door is unlatched. (Hold the door in a closed position with ona hand, then push the open button with the other, this causes the latch heads to rise, it is then possible to hear a "click" as the door switches operate.) 3.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE OUTER CASE REMOVAL To remove the outer case, proceed as follows. 1. Disconnect oven from power supply. 2. Open door and wedge it open. 3. Remove the one (1) screw holding the air duct to the oven cavity rear plate. 4. Remove athe air duct. 5. Remove the nine (9) screws from rear and along the side edge of case. 6. Slide the entire case back about 3 cm to free it from retaining clips on the cavity face plate. 7. Lift the entire case from the oven. 8.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE CONTROL PANEL ASSEMBLY REMOVAL 1. CARRY OUT 3D CHECKS. 2. Disconnect the main wire harness from the control panel. 3. Remove the one (1) screw holding the control panel to the oven cavity. 4. Lift the control panel assembly and pull it forward. Now, the control panel assembly is free. FAN MOTOR REPLACEMENT REMOVAL 1. CARRY OUT 3D CHECKS. 2. Remove the one (1) screw holding the noise filter to the chassis support. 3.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE TURNTABLE MOTOR REPLACEMENT REMOVAL 1. Disconnect the oven from the power supply. 2. Remove the turntable and roller stay from the oven cavity. 3. Turn the oven over. 4. Cut the three (3) bridges holding the turntable motor cover to the base plate with cutting pliers as shown in Figure C-1(a). CAUTION: DO NOT DROP THE TURNTABLE MOTOR COVER INTO THE OVEN AFTER CUTTING THE BRIDGES.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 5. Remove the cooling fan from the convection motor shaft. 6. Remove the two (2) screws holding the convection motor to the convection motor angle. 7. Remove the one (1) ring from the convection motor shaft. 8. Now, the convection motor is free. CONVECTION MOTOR REMOVAL 1. Remove the one (1) nut and washer from the convection motor shaft. 2. Remove the convection fan from the convection motor shaft. 3. Remove the pipe from the convection motor shaft. 4.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE GRILL HEATING ELEMENTS REMOVAL 1. CARRY OUT 3D CHECKS. 2. Disconnect wire leads from the thermal cut-out (GRILL). 3. Remove the two (2)screws holding the two (2) terminals of the main wire harness to the two (2) grill heating elements. 4. Remove the one (1) screw holding the exhaust duct to the oven cavity top plate. 5. Remove the exhaust duct from the oven cavity top plate. 6.
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE DOOR REPLACEMENT REMOVAL 1. Disconnect the oven from the power supply. 2. Push the door slightly. 3. Remove the door stopper from the choke cover. 4. Lift the door upwards. 5. Now, door assembly is free from oven cavity. 6. Insert an putty knife (thickness of about 0.5mm) into the gap between the choke cover and door frame as shown in Figure C-7 to free engaging parts. 8. Now choke cover is free. 9. Release choke cover from door panel.
MICROWAVE MEASUREMENT After adjustment of door latch switches, monitor switch and door are completed individually or collectively, the following leakage test must be performed with a survey instrument and it must be confirmed that the result meets the requirements of the performance standard for microwave oven. REQUIREMENT The safety switch must prevent microwave radiation emission in excess of 5mW/cm2 at any point 5 cm or more from external surface of the oven.
SCHEMATICS SCHEMATIC NOTE:CONDITION OF OVEN 1. DOOR CLOSED 2. PLUGGED IN OVEN. 3. NOTHING APPEARS ON DISPLAY. Note: AC CORD CONNECTION BRN: BROWN BLU: BLUE G-Y: GREEN AND YELLOW STRIPE /15: SECTION AREA OF 1.5mm2 MIN. ” Indicates components with potential above 250V. TC2 : GRILL THERMAL CUT-OFF C: CAPACITOR H.V.
SCHEMATICS SCHEMATIC NOTE:CONDITION OF OVEN 1. DOOR CLOSED 2. “ . 0” APPEARS ON DISPLAY. Note: AC CORD CONNECTION BRN: BROWN BLU: BLUE G-Y: GREEN AND YELLOW STRIPE /15: SECTION AREA OF 1.5mm2 MIN. ” Indicates components with potential above 250V. TC2 : GRILL THERMAL CUT-OFF SW1 : C: CAPACITOR H.V.
SCHEMATICS H.V. RECTIFIER T: HIGH VOLTAGE TRANSFORMER C: CAPACITOR TURNTABLE MOTOR FAN MOTOR GH: GRILL HEATING ELEMENTS SW2: STOP SWITCH CH: CONVECTION HEATING ELEMENT SW4: THERMISTOR DAMPER SWITCH CONVECTION MOTOR CONTROL UNIT OVEN LAMP DAMPER MOTOR T/C TRANSFORMER NOISE SUPRESSION COIL TC1 : MAG THERMAL CUT-OFF TC3: CONV. THERMO CUT-OUT F2:FUSE F8A NOTE: The convection cooking will be carried out as back up until the oven cavity temperature rises to 220°C.
SCHEMATICS ” “ Indicates components with potential above 250V. TC2 : GRILL THERMAL CUT-OFF SW1 : H.V. RECTIFIER T: HIGH VOLTAGE TRANSFORMER C: CAPACITOR TURNTABLE MOTOR FAN MOTOR CONVECTION MOTOR GH: GRILL HEATING ELEMENTS SW2: STOP SWITCH CH: CONVECTION HEATING ELEMENT SW4: THERMISTOR DAMPER SWITCH OVEN LAMP DAMPER MOTOR T/C TRANSFORMER TC1 : MAG THERMAL CUT-OFF TC3: CONV.
SOI 12.06 FV FM: FAN MOTOR CH: CONVECTION HEATING ELEMENT SW4: DAMPER SWITCH 43/43 TC3: CM: CONVECTION MOTOR NOISE FILTER THERMAL CUT-OUT(CONV.) POWER SUPPLY CORD T: HIGH VOLTAGE TRANSFORMER Red wire Long Black Tube H.V.
