LG MS-304W Service Manual Download Page 8

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4-2

The following is a description of component functions
during oven operation.

1. SETTING THE CLOCK

2. MICROWAVE COOKING

3. AUTO WEIGHT DEFROST

4. AUTO COOK

5. CHILD LOCK

This oven has a CHILD LOCK feature.
To Set CHILD LOCK

To Cancel CHILD LOCK

6. QUICK START

7. MORE AND LESS

Operating Sequence

Clock

Desired

minute

Start

Desired

hour

Stop/Clear

Desired

power

level

Desired

cooking

time

Start

Stop/Clear

(Touch and Hold)

Stop/Clear

(Touch and Hold)

Stop/Clear

Start

Stop/Clear

Less

Desired auto cook

Stop/Clear

Desired

defrost

Summary of Contents for MS-304W

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MS 304W MS 304WB MS 304WG MS 304WS CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL ...

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 11 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: ...366 D mm 16 kg 17 kg Microwave Power for Variable 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 Owner s manual Glass turntable Rotating ring 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outsid...

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: ...of power level cooking category 6 COOK TIME Used to cook food for a desired time 7 MORE LESS Used to change the cooking time desired weight 8 STOP CLEAR Used to stop oven and clear all entries except time of day 9 START Q START To quickly set the cooking time directly 10 CLOCK Used to set the time of day 11 KITCHEN TIMER Turntable Rotating Ring Oven Front Plate Window Door Screen Safety Door Lock ...

Page 8: ...K To Cancel CHILD LOCK 6 QUICK START 7 MORE AND LESS Operating Sequence Clock Desired minute Start Desired hour Stop Clear Stop Clear Desired power level Desired cooking time Start Stop Clear Stop Clear Touch and Hold Stop Clear Stop Clear Touch and Hold Stop Clear Start Stop Clear More Less Desired auto cook Stop Clear Desired defrost category Food weight Start Stop Clear Desired auto cook catego...

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

Page 10: ...h voltage of approximately 2100 volts AC is generated in the secondary of the high voltage transformer which is increased by the action of the high voltage diode and charging of the high voltage capacitor The negative 4 000 Volts 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 si...

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: ...ND ADJUSTMENT OF THE LATCH BOARD TO THE OVEN ASSEMBLY Mount the latch board to the oven assembly Adjust the latch board in the arrow direction so that oven door will not have any play in it when the door is closed Tighten the mounting screw Check for play in the door by pushing the door release button Door movement should be less than 0 5 mm 1 64 inch Don t push the door release button while makin...

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: ... 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 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 ...

Page 20: ...tive switch and the fuse at the same time Replace just the fuse if the switches operate normally Normal Abnormal 0 C Approx 110 C Approx 110 C Cooking Start OFF Check for P C B connector Measure the resistance 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 100 200 Ω Abnormal Infinite or several ohm NOTE...

Page 21: ...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 22: ... 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 No input can be programmed Continuity No continuity Defective PCB assembly Loose connection Replace PCB assembly Connect them tigh...

Page 23: ...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 24: ...ch with 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 Abnormal Abnormal Measure the output power Disconnect the wire leads from relay 2 and check on and off time with mult...

Page 25: ... 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 26: ...e 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 ...

Page 27: ...INTERIOR PARTS OVEN CAVITY PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS BASE PLATE PARTS 6 1 EXPLODED VIEW INTRODUCTION ...

Page 28: ...6 2 13536A 13581A 14970A 14026A 13552A 13213A 14890A 13720D 15006A DOOR PARTS ...

Page 29: ...6 3 WTP015 WTP004 23506A 23572A 24781M 268711 CONTROL PANEL PARTS ...

Page 30: ...6 4 33052A 34960A 33390G 35889A 34370T 36549S WTP013 WTT010 WTT021 33112U OVEN CAVITY PARTS ...

Page 31: ...6 5 466001 43500A 44510A 466001 43501A WSZ085 466003 LATCH BOARD PARTS ...

Page 32: ... WSZ002 WTT028 WSZ002 WTT028 WSZ062 WSZ002 WTT037 WSZ002 50CZZH 56324A 34930W 55262A 54810C 55900A 56549F 56411A 56930V 568771 54974S 56912B 948501 56851D 948502 948504 50FZZA 56201A WSZ002 INTERIOR PARTS ...

Page 33: ...6 7 WTT021 63302A 63303A 56170D WSZ002 WTT030 647781 948503 BASE PLATE PARTS ...

Page 34: ... LATCH R 43501A 3501W1A016F BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 3B73362F SWITCH MICRO R 6600W1K004C 466003 3B73361E SWITCH MICRO R 6600W1K004B 50CZZH 6120W3H003J CAPACITOR DRAWING HIGH VOLTAGE R 0CZZW1H002J 50FZZA 3B70856T FUSE DRAWING R 54810C 4810W4C003A BRACKET CAPACITOR R 54974S 4974W1S010A GUIDE SUCTION R 55262A 5262W2A018B DUCT R 55900A 2B72125A FAN R 56170D 6170W1D068B ...

Page 35: ...G PAN HEAD R WTP015 1TPL0402618 SCREW TAPPING PAN HEAD R WTT010 1TTG0402422 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT030 1TTL0403118 SCREW TAPPING TRUSS HEAD R WTT037 1TTL0403818 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R SERVICE PARTS NO ...

Page 36: ...501A 3501W1A016F BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 3B73362F SWITCH MICRO R 6600W1K004C 466003 3B73361E SWITCH MICRO R 6600W1K004B 50CZZH 6120W3H003J CAPACITOR DRAWING HIGH VOLTAGE R 0CZZW1H002J 50FZZA 3B70856T FUSE DRAWING R 54810C 4810W4C003A BRACKET CAPACITOR R 54974S 4974W1S010A GUIDE SUCTION R 55262A 5262W2A018B DUCT R 55900A 2B72125A FAN R 56170D 6170W1D068B TRANSFORMER...

Page 37: ...G PAN HEAD R WTP015 1TPL0402618 SCREW TAPPING PAN HEAD R WTT010 1TTG0402422 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT030 1TTL0403118 SCREW TAPPING TRUSS HEAD R WTT037 1TTL0403818 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R SERVICE PARTS NO ...

Page 38: ...501A 3501W1A016F BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 3B73362F SWITCH MICRO R 6600W1K004C 466003 3B73361E SWITCH MICRO R 6600W1K004B 50CZZH 6120W3H003J CAPACITOR DRAWING HIGH VOLTAGE R 0CZZW1H002J 50FZZA 3B70856T FUSE DRAWING R 54810C 4810W4C003A BRACKET CAPACITOR R 54974S 4974W1S010A GUIDE SUCTION R 55262A 5262W2A018B DUCT R 55900A 2B72125A FAN R 56170D 6170W1D068B TRANSFORMER...

Page 39: ...G PAN HEAD R WTP015 1TPL0402618 SCREW TAPPING PAN HEAD R WTT010 1TTG0402422 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT030 1TTL0403118 SCREW TAPPING TRUSS HEAD R WTT037 1TTL0403818 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R SERVICE PARTS NO ...

Page 40: ...501A 3501W1A016F BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 3B73362F SWITCH MICRO R 6600W1K004C 466003 3B73361E SWITCH MICRO R 6600W1K004B 50CZZH 6120W3H003J CAPACITOR DRAWING HIGH VOLTAGE R 0CZZW1H002J 50FZZA 3B70856T FUSE DRAWING R 54810C 4810W4C003A BRACKET CAPACITOR R 54974S 4974W1S010A GUIDE SUCTION R 55262A 5262W2A018B DUCT R 55900A 2B72125A FAN R 56170D 6170W1D068B TRANSFORMER...

Page 41: ...G PAN HEAD R WTP015 1TPL0402618 SCREW TAPPING PAN HEAD R WTT010 1TTG0402422 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT030 1TTL0403118 SCREW TAPPING TRUSS HEAD R WTT037 1TTL0403818 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R SERVICE PARTS NO ...

Page 42: ...8 1 SCHEMATIC DIAGRAM OF P C B ...

Page 43: ...8 2 PRINTED CIRCUIT BOARD ...

Page 44: ...FIERS 1N4002 PYUNG CHANG TP26 DO41 100V 1A 30A R D06 0DD400209AA DIODE RECTIFIERS 1N4002 PYUNG CHANG TP26 DO41 100V 1A 30A R D07 0DD400209AA DIODE RECTIFIERS 1N4002 PYUNG CHANG TP26 DO41 100V 1A 30A R D08 0DD400209AA DIODE RECTIFIERS 1N4002 PYUNG CHANG TP26 DO41 100V 1A 30A R D09 0DD400209AA DIODE RECTIFIERS 1N4002 PYUNG CHANG TP26 DO41 100V 1A 30A R D25 0DD414809AA DIODE SWITCHING 1N4148 ROHM TP2...

Page 45: ...ILM 100 OHM 1 4 W 5 TA26 R R112 0RD1000G608 RESISTOR FIXED CARBON FILM 100 OHM 1 4 W 5 TA26 R R113 0RD1000G608 RESISTOR FIXED CARBON FILM 100 OHM 1 4 W 5 TA26 R R114 0RD1000G608 RESISTOR FIXED CARBON FILM 100 OHM 1 4 W 5 TA26 R R115 0RD1000G608 RESISTOR FIXED CARBON FILM 100 OHM 1 4 W 5 TA26 R R116 0RD1000F608 RESISTOR FIXED CARBON FILM 100 OHM 1 6 W 5 TA26 R R117 0RD1000F608 RESISTOR FIXED CARBON...

Page 46: ...ON FILM 47K OHM 1 6 W 5 TA26 R R90 0RD4701G608 RESISTOR FIXED CARBON FILM 4 7K OHM 1 4 W 5 TA26 R R91 0RD4701F608 RESISTOR FIXED CARBON FILM 4 7K OHM 1 6 W 5 TA26 R R92 0RD4701F608 RESISTOR FIXED CARBON FILM 4 7K OHM 1 6 W 5 TA26 R R93 0RD4701G608 RESISTOR FIXED CARBON FILM 4 7K OHM 1 4 W 5 TA26 R RY1 6920WRD008A RELAY JQ1A 12V MATSUSHITA 250VAC 5A 12VDC 1A N R 6920W2D010B RY2 6920W5A012A RELAY G5...

Page 47: ...P NO 3828W5S2207 May 2002 Printed in Korea ...

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