LG MC-8083MLR, Service Manual

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MC 9283JR CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com ...

Page 2: ...r 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...

Page 3: ... CIRCUIT DESCRIPTION 4 4 SERVICE INFORMATION 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 DISASSEMBLY AND ADJUSTMENT 5 3 INTERLOCK CONTINUITY TEST 5 7 COMPONENT TEST PROCEDURE 5 8 TROUBLE SHOOTING 5 13 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 SCHEMATIC DIAGRAM OF P C B 8 1 PRINTED CIRCUIT BOARD 8 2 P C B PARTS LIST 9 1 CONTENTS ...

Page 4: ...able Cooking Power level MAX 900W Full power throughout the cooking time MED HIGH 720W approx 80 of Full power MEDIUM 540W approx 60 of Full power DEFROST 360W approx 40 of Full power LOW WARM 180W approx 20 of Full power CONVECTION Max 250 C GRILL COMBINATION Owner s manual Cook book Glass turntable Rotating ring Grill rack Convection rack Metal tray Handle Rotisserie bar 1 1 ITEM MODEL Power Req...

Page 5: ...tron be assembled to the waveguide and cavity Never operate the magnetron unless it is properly installed Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron 2 1 CAUTIONS Unlike other appliances the microwave oven is high voltage and high current equipment Though it is free from danger in ordinary use extreme care should be taken du...

Page 6: ...to prevent interference 8 Do not touch the front glass during or after cooking of the Grill and Combination mode This glass is very hot during heater operating 9 Do not operate the oven at microwave and combination mode with Grill rack placed in the cavity when the oven is empty EARTHING INSTRUCTIONS This microwave oven is designed to be used in a fully earthed condition It is imperative therefore...

Page 7: ...er levels 3 GRILL To select grill cooking 4 CONVECTION To select convection cooking 5 COMBI To select combi cooking 6 AUSSIE MENUS 7 AUTO COOK Used to select the auto cook 8 AUTO REHEAT Used to select the auto reheat 9 AUTO ROAST Used to select the auto roast 10 Q DEFROST Used to select the quick defrost 11 AUTO DEFROST Used to select the auto weight defrost 12 DIAL To select convection temperatur...

Page 8: ...ing time Start Stop Clear Function Grill Desired cooking time Desired cooking time Start Stop Clear Start Stop Clear Dial Turn right and left Desired auto cook Stop Clear Stop Clear Function Combi 1 Desired defrost category Food weight Food weight Start Stop Clear Desired Aussie menus category Start Stop Clear Desired auto cook category Food weight Start Start Stop Clear Function Convection Desire...

Page 9: ...SCHEMATIC DIAGRAM 4 3 ...

Page 10: ... is applied to the filament of the magnetron WHEN THE OVEN IS SET AT ANY LEVEL EXCEPT MAXIMUM The micom controller controls the ON OFF time of relay 2 by the applied signal to vary the average output power of microwave oven as POWER LEVEL refer to page 1 1 One complete cycle of relay 2 is 22 seconds WHEN THE DOOR IS OPENED DURING COOKING Both the primary switch and relay 2 are cut off primary wind...

Page 11: ...ich is graduated to 600 cc and place the beaker on the center of the turntable Set the energy leakage monitor to 2 450 MHz and use it following the manufacturer s recommended test procedure to assure correct result When measuring the leakage always use the 2 inch 5cm spacer supplied with the probe Operate the oven at its maximum output Measure the microwave radiation using and electromagnetic radi...

Page 12: ...e test probe must be removed no faster than 1 inch sec 2 5 cm sec along the shaded area otherwise a false reading may result The test probe must be held with the grip portion of the handle A false reading may result if the operator s hand is between the handle and the probe When testing near a corner of the door keep the probe perpendicular to the surface making sure the probe horizontally along t...

Page 13: ...re is 5 K The microwave power output P in watts is calculated from the following formula P is measured while the microwave generator is operating at full power Magnetron filament heat up time is not included The water is stirred to equalize temperature throughout the vessel prior to measuring the final water temperature Stirring devices and measuring instruments are selected in order to minimize a...

Page 14: ...ltage transformer and capacitor 3 Remove the screw holding the high voltage transformer to the baseplate F AIR DUCT ASSEMBLY REMOVAL 1 Disconnect the leadwire from lamp and MGT thermostat 2 Remove the mounting screw to the magnetron G MAGNETRON REMOVAL 1 Disconnect the leadwire from the high voltage transformer and high voltage capacitor 2 Carefully remove the mounting screws holding the magnetron...

Page 15: ...ltage diode earth screw 4 Remove the screw holding the high voltage capacitor bracket J THE TURNTABLE MOTOR REMOVAL 1 Remove the turntable 2 Remove the turntable shaft VERY CAREFULLY with a slotted screwdriver 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base cover is easily removed by pinching the six parts with a wire cutting 5 Disconnect the leadwire from the...

Page 16: ...n previous page 2 Remove screws which hold the PCB SUB ASS Y to the control panel 3 Take off the PCB SUB ASS Y from the control panel M INTERLOCK SYSTEM 1 INTERLOCK MECHANISM The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage 2 MOU...

Page 17: ... closed meter should indicate an closed circuit When the secondary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch C MONITOR SWITCH TEST Disconnect the wire lead from the monitor switch Connect the ohmmeter leads to the common COM and normally closed NC terminals of the switch The meter should indicate closed circuit in the door op...

Page 18: ... RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Secondary winding Filament winding 2 Measure the resistance Ohm meter scale Rx1000 Primary winding to ground Filament winding to ground 1 Measure the resistance Ohm meter scale Rx1 Filament terminal 2 Measure the resistance Ohm meter scale Rx1000 ...

Page 19: ...1000 Terminal to case Measure the continuity Forward Ohm meter scale Rx10000 Measure the continuity Reverse Ohm meter scale Rx10000 Normal Momentarily indicates several ohms and then gradually returns to infinite Normal Infinite NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition Antenna Gasket Chassis Fil...

Page 20: ... by improper switch operation replace the defective switch and the fuse at the same time Replace just the fuse if the switches operate normally NOTE Make sure heater is fully cooled when tested Measure the resistance Multi meter scale Rx1 Normal Grill heater Approx 42 ohm at 20 30o C Convection heater Approx 40 ohm at 20 30o C Normal more than 0 5 Mohm Normal Abnormal Measure the resistance with 5...

Page 21: ...esistance Ohm meter scale R x 1 Measure the resistance Ohm meter scale R x 1000 Normal Approx 200 400 ohm Abnormal Infinite or several ohm Normal Approx 10 20 kohm Abnormal Infinite or several ohm NOTE A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO...

Page 22: ...e RY3 Grill RY5 Convection Normal COM 230V Approx 150 Ω Abnormal Infinite or several ohm NOTE A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE CORRECT POSITION WHEN REMOVING THE WIRE LEAD FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES 5 12 Cooking Start OFF Cooking Start OFF COM YL 230V BL CN2 1 3 5 7 9 Rela...

Page 23: ...el to discharge any static charge built up in your body CONDITION Microwave oven does not work Inserting many plug into one plug outlet and using them at the same time causes overloading Microwave oven plug is not inserted tightly Output power is too low Low AC input voltage Food temperature is too low Using metallic ware and allowing it to touch the oven wall Sparks occurring Inconsistent intensi...

Page 24: ...own 9 Display counts down too fast while cooking 10 Each indicator light does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished 12 Beep sound is not heard when correct key is touched TROUBLE 1 The following visual conditions indicate a probable defective control circuit CONDITION CHECK RESULT CAUSE REMEDY 1 Some inputs cannot be programmed 2 ...

Page 25: ...ch with door closed Check continuity of primary switch with door opened Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit Replace fuse TROUBLE 2 Oven does not operate at all Display window does not display any figures and no input is accepted NOTE All these switches must be replaced at the same time Refer to page 5 6 5 7 2 Fuse does ...

Page 26: ...ith door closed Check fan motor Check oven lamp Abnormal Abnormal Normal Defective fan motor Defective fan motor Replace fan motor Replace fan motor Loose connection Connection then tightly CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 of rating voltage Normal Normal Abnormal Abnormal Measure the output power Disconnect the wire leads from relay 2 and check on and off time with m...

Page 27: ... Defective high voltage transformer Replace high voltage transformer Check H V transformer normal normal Abnormal Defective high voltage Diode Replace high voltage Diode Check H V diode Abnormal Defective high voltage capacitor Replace high voltage capacitor Check H V capacitor Abnormal Defective magnetron Replace magnetron Check Magnetron TROUBLE 5 No microwave oscillation even though oven lamp a...

Page 28: ...function the heater Replace Replace TROUBLE 6 Oven does not cook properly when programmed for the set power level Operates properly on HIGH CONDITION CHECK RESULT CAUSE REMEDY Output is full when you set lower power level Abnormal Disconnect the wire leads from relay 2 and check continuity relay 2 Operate the unit Defective P C B assembly Replace P C B assembly NOTE Make sure the wore leads correc...

Page 29: ...DOOR PARTS CONTROL PANEL PARTS BASE PARTS INTERIOR PARTS OVEN CAVITY PARTS LATCH BOARD PARTS 6 1 EXPLODED VIEW INTRODUCTION ...

Page 30: ...6 2 15006A 13581A 14970A WTP027 14026A 13552A 13536A 13213A 14890A 13720D 13650A DOOR PARTS ...

Page 31: ...6 3 24781M 249401 250202 250201 268712 268711 23572A 23790D WTP004 WTP015 CONTROL PANEL PARTS ...

Page 32: ...1A 348101 35300A 348102 33550H WMT002 35889A 33301L 34270A 34271A 33650T 33301R 33390G 33390M WTT011 WTP013 36549S 34370T 33052M 35264A WTT021 WTT011 36549R 34960A 34930R WTT011 34370Z WTP013 35026C 35026G 34810R OVEN CAVITY PARTS ...

Page 33: ...6 5 WSZ085 WTT028 43500A 43501A 466001 44510A 466003 466001 WTT028 56912B 55262A 53550L LATCH BOARD PARTS ...

Page 34: ...810C WTT028 50CZZH 50FZZA 56201A WSZ002 56851D 54620A 55900N 54810S 56322A WTT022 53504A 53300G 54350S 349801 56208A WTT022 36549C WNH002 WSZ059 WNH003 WWP008 WWS005 33808A WMT002 348105 348104 55300S 55900C 348103 WTT021 56930M 54810A 56324A 56201B WSZ002 WTP002 INTERIOR PARTS ...

Page 35: ...6 7 63303A 56170D 63302A 65006B WTT021 WSZ002 BASE PLATE PARTS ...

Page 36: ...8 1 SCHEMATIC DIAGRAM OF P C B ...

Page 37: ...8 2 PRINTED CIRCUIT BOARD ...

Page 38: ...P NO 3828W5S3477 Jan 2004 Printed in Korea ...