LG MC-8483NL Service Manual Download Page 1

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MICROWAVE OVEN

SERVICE MANUAL

MODEL: MC-8483NL

CAUTION

BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

Website http://biz.lgservice.com

P/NO : 3828W5S6029

September, 2004

Printed in Korea

Summary of Contents for MC-8483NL

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MC 8483NL CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO 3828W5S6029 September 2004 Printed in Korea ...

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: ...TING SEQUENCE 4 2 SCHEMATIC DIAGRAM 4 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 CONTENTS ...

Page 4: ...0W Full power throughout the cooking time Saute 855W approx 90 of Full power Med High 665W approx 70 Med Low 475W approx 50 Low 285W approx 30 Warm 95W approx 10 CONVECTION Max 250 C GRILL Owner s manual Cook book Glass turntable Roller rest High rack Low rack Steam cover Steam plate Steam water bowl Metal tray 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outsi...

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: ...ean mode custom set mode convection combination mode and convection mode 6 DIAL To select convection temperature change cooking time and weight 7 AUTO DEFROST To select auto defrost 8 AUTO REHEAT To select auto reheat 9 STOP CLEAR Used to stop oven and clear all entries except time of day 10 START Q START To quickly set the cooking time directly Turntable Roller Rest High Rack Low Rack STEAM COVER...

Page 8: ...250 C Enter Stop Clear Select Grill combi Desired cooking level Desired cooking time Start Enter Stop Clear Select Conv combi Desired cooking level Enter Stop Clear Select Steam Keep Warm Desired Warming temp Warm Hi Warm Low Enter Desired Warming time Start DesiredConv temp 100 C 250 C Enter Desired cooking time Start Stop Clear Select Speed hot air Desired convection temp 100 C 250 C Start Stop ...

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

Page 10: ...ts DC 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...

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: ...mperature after heating T0 Temperature of bowl M Weight of bowl 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 addition or removal of heat ...

Page 14: ...EMBLY 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 and the waveguide 3 Remove the magnetron ASS Y until the tube is clear from the waveguide NOTE 1 When removing the mag...

Page 15: ...Disconnect the leadwire from magnetron high voltage transformer and capacitor 3 Remove the screw holding the high voltage transformer to the baseplate K 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...

Page 16: ...o the motor bracket 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 MOUNTING OF THE PRIMARY MONITOR SECONDARY SWITCHES TO THE LATCH BOARD 3 INSTALLATION AND ADJUSTMENT OF THE LATCH BOAR...

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: ...inal 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 Normal Continuity Abnormal Infinite Normal Infinite Abnormal Continuity NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure ...

Page 20: ...n 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 30oC Convection heater Approx 40 ohm at 20 30o C Normal more than 0 5 Mohm Normal Abnormal Measure the resistance with 5...

Page 21: ...Measure the resistance Ohm meter scale R x 1000 Check for P C B connector 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 GRASP...

Page 22: ...ave RY3 Grill RY5 Convection 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 Cooking Start OFF COM YL 230V BL CN2 1 4 5 6 9 Relay 4 Relay 1 Relay 6 Relay 2 Relay 3 Relay 5 Cooking Start OFF Normal COM 230V Appro...

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: ... 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 5 14 TROUBLE 1 The following visual conditions indicate a probable defective control circuit CONDITION CHECK RESULT CAUSE REMEDY Everything works as specified Still h...

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: ...with door closed Check fan motor Check oven lamp Abnormal Abnormal Normal Defective fan motor Defective oven lamp Replace fan motor Replace oven lamp 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 ...

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 INTERIOR PARTS OVEN CAVITY PARTS LATCH BOARD PARTS BASE PLATE PARTS 6 1 EXPLODED VIEW INTRODUCTION EV ...

Page 30: ... SERVICE PARTS 13552A 13581A 14026A WTT030 13551A 15006A 14970A WTT024 13213A 13650A 14980A Model No CHANGED THE PART IN THE SECTION OR CIRCUIT DOOR FRAME SEAL TAPE Stock New Parts DESCRIPTION DOOR FRAME DOOR PARTS EV ...

Page 31: ... 6 3 24781S 249401 23520A 249402 268711 WTP004 WTP015 23551A 250201 23790D 250202 243501 CONTROL PANEL PARTS EV ...

Page 32: ... 6 4 33550S 35026C 35026S 36549S WTP013 33112U WTT022 WTT022 33390M 35026G 33390G 35889A 33052M WTT029 33651A OVEN CAVITY PARTS EV ...

Page 33: ... 6 5 WSZ085 43501A 466001 43500A 466003 44510A 466001 LATCH BOARD PARTS EV ...

Page 34: ...8 WSZ002 50CZZH 56549F 54810C 948503 56324A 55262A 948501 56930M 56912B 55900A WTT021 WNH002 55900N 348103 348102 535041 WMT002 WTT029 54350S WWZ085 WWS005 WNH003 WSZ059 56208A 55900C 348101 568772 35300S WSZ002 350122 WTT021 WSZ002 WTT021 WTT021 34810H After 56851C Original New Early Late New parts only may be used in early or late production sets Stock new Parts Before INTERIOR PARTS EV ...

Page 35: ... 6 7 63302A 63303A 56170D 647781 WTT030 WSZ002 948502 WTT028 WTT021 BASE PLATE PARTS EV ...

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