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This device is to be serviced only by properly qualified service personnel.
Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be
taken to avoid possible exposure to excessive microwave energy.

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.

SAFETY PRECAUTIONS

CAUTION

MICROWAVE RADIATION

DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR
OR OTHER PARTS CONDUCTING MICROWAVE ENERGY.

LGE Internal Use Only

Copyright © 2009 LG Electronics. Inc. All right reserved. 
Only for training and service purposes

Summary of Contents for MJ3283BKG

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MJ3283BKG CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL July 2013 Printed in India 삼 흥 정 판 Internal Use Only ...

Page 2: ... 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 ...

Page 3: ...ON 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 LGE Internal Use Only Copyright 2009 LG Electronics Inc All right reserved Only for training and s...

Page 4: ...r 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 230 C GRILL COMBINATION Owner s manual and Recipe Manual Glass Tray Rotating ring High rack Low rack Multi Rotisserie and Rotisserie Handle Steam Chef ITEM MODEL Power Requirement Power Output Microwave Fre...

Page 5: ...te 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 during repair THE OVEN IS TO BE SERVICED ONLY BY PROPERLY Q...

Page 6: ...uring 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 to make sure it is properly earthed before servicing WA...

Page 7: ...2009 LG Electronics Inc All right reserved Only for training and service purposes Multicook Tawa START Add 30 Secs STOP Clear CHARCOAL Check the recipe manual Check the recipe manual Check the recipe manual 24 Hours Kids Delight COOK MODE DIAL Check the recipe manual Nutri Care Check the recipe manual Indian Rasoi Check the recipe manual Just 4 U Utility corner START Add 30 Secs Check the recipe m...

Page 8: ...OOK MODE STOP CLEAR GRILL TEMP CONTROL COOK MODE START QUICKSTART START QUICKSTART COOK MODE COOK MODE START QUICKSTART START QUICKSTART COOK MODE COOK MODE COOK MODE START QUICKSTART STOP CLEAR START QUICKSTART START QUICKSTART COOK MODE COOK MODE COOK MODE START QUICKSTART COOK MODE START QUICKSTART STOP CLEAR STOP CLEAR Touch and Hold STOP CLEAR STOP CLEAR Touch and Hold STOP CLEAR Desired cook...

Page 9: ...SCHEMATIC DIAGRAM 4 3 LGE Internal Use Only Copyright 2009 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 10: ...IMUM 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 winding voltage of the high voltage transformer ON OFF of relay 2 is coupled electrically wit...

Page 11: ...nter 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 radiation monitor by holding the probe perpendicular to the s...

Page 12: ... 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 is moved horizontally along the oven surface RECORD KEEPING AND...

Page 13: ... is calculated from the following formula 4187 x T 0 55 X T2 T0 X M T T2 Temperature 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...

Page 14: ...t 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 magnetron make sure its dome...

Page 15: ... TURNTABLE MOTOR 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 turntable motor terminals 6 Remove the screw securing the turntable motor to the oven cavity ASS Y...

Page 16: ...SS Y to the control panel 3 Disconnect the flat cable from the PCB SUB ASS Y and take off the PCB SUB ASS Y M INTERLOCK SYSTEM 1 INTERLOCK MECHANISM The door lock mechanism is a device which has been specially designed to eliminate 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 SECONDAR...

Page 17: ...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 open condition When the door is closed meter should indicat...

Page 18: ...R 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 Filament to chassis Approx 1 9 o...

Page 19: ...r 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 that the gasket is in good condition Antenna Gasket ...

Page 20: ... 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 Normal more than 0 5 Mohm Normal Abnormal Measure the resistance with 500V 100M ohm insulation resistance meter 0 C Approx 145 ...

Page 21: ...r 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 THE CONNECTOR NOT THE WIRES A B Cooking Start OFF Relay...

Page 22: ...KAGE 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 Relay 2 Relay 3 Relay 5 Cooking Start OFF CN2 1 3 4 5 9 6 8 Relay 6 Relay 4 COM YL 230V BL Cooking Start OFF Normal COM 230V Approx 150 Ω Abnormal Infinite or several ohm LGE Internal Use On...

Page 23: ...ONDITION 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 intensity of microwave by their characteristics 1 Wrap the thinn...

Page 24: ...r 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 Continuity No continuity Still have trouble Defective key membrane assembly Defective PCB assembly Loose connection Defective PCB assembly Replace key membrane...

Page 25: ...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 not blow No continuity No continuity Replace power supply cord Defective mag netron thermostat Defective power supply c...

Page 26: ... 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 multitester Defective P C B asse...

Page 27: ...ormal 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 No microwave oscillation even though oven lamp and fa...

Page 28: ... 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 are in the correct position When removing the wire leads from parts be sure to ...

Page 29: ...5 19 ...

Page 30: ...5 20 ...

Page 31: ...5 21 ...

Page 32: ...DOOR PARTS CONTROL PANEL PARTS LATCH BOARD PARTS BASE PLATE PARTS INTERIOR PARTS OVEN CAVITY PARTS OWNERS MANUAL COOK BOOK 6 1 EXPLODED VIEW INTRODUCTION EV MODEL ...

Page 33: ... 6 2 13581A DOOR PARTS EV 14510L ...

Page 34: ... 6 3 CONTROL PANEL PARTS EV 24781S ...

Page 35: ... 6 4 OVEN CAVITY PARTS EV 35026C 35026G 34370T 35889A 33390G 36549S 33390M 35300A 353002 335021 445101 33301R 33390C 44980A 445102 43500A 348102 330522 33550S 55238B 55238A 33112U ...

Page 36: ... 6 5 LATCH BOARD PARTS EV 43501A 466003 466003 466001 43500B 568771 ...

Page 37: ... 6 6 56411A 568772 56912B 56930V INTERIOR PARTS EV 54974S 56930G 55300A 535041 535042 55900C 568774 56322A 55900N 36549C 56930H 34810H 34810H 56851D 56324A 56851F 56851E ...

Page 38: ... 6 7 BASE PLATE PARTS EV 64970A 647781 56170D ...

Page 39: ...7 1 REPLACEMENT PARTS LIST R SERVICE PARTS ...

Page 40: ......

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