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LG MS-72NA, Service Manual

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LG MS-72NA Service Manual Download Page 28

6-5

SUCTION GUIDE PARTS

466001

466003

WTT028

466001

43500A

56912B

55262A

43501A

WSZ085

#EV#

Summary of Contents for MS-72NA

Page 1: ... 3828W5S1787 Website http biz lgservice com April 2001 Printed in Korea MICROWAVE OVEN SERVICE MANUAL MODEL MS 72NA CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL NOM 061 NYCE ...

Page 2: ...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 interloc...

Page 3: ...ATING PROCEDURE 4 1 SCHEMATIC DIAGRAM 4 2 CIRCUIT DESCRIPTION 4 3 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 8 COMPONENT TEST PROCEDURE 5 9 TROUBLE SHOOTING 5 12 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 CONTENTS ...

Page 4: ... Complement Nameplate Location Accessories DESCRIPTION MS 72NA 120 Volts AC 60 Hz 1 050 Watts 9 3A Single phase 3 wire grounded 700 Watts full microwave power IEC60705 2 450 MHz 2M213 09 0 60 min 19 W x 11 H x 127 8 D mm 117 8 W x 75 8 H x 121 2 D mm 25 lbs approx 28 lbs approx Microwave Power for Variable Cooking Power level Máximo calentar Hornear Descongelar Entibiar Owner s manual cooking guid...

Page 5: ... operation of the microwave oven requires that the magnetron 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 fro...

Page 6: ...age the electronic or mechanical parts of the unit Do not install the oven next to a conventional surface unit or above a conventional wall oven 5 Use microwave oven in an ambient temperature less than 104 F 40 C 6 Place the microwave oven on a sturdy and flat surface at least 10 cm 4 inches from the wall 7 Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent inte...

Page 7: ...nd then back to the proposed setting 2 The door can be opened during the cooking process by pushing the Door Open Button The timer will stop and the microwave activity will cease When the door is closed cooking will resume until the full cooking time has elapsed After cooking is finished the Timer will be at OFF After unpacking this appliance examine the new oven for evidence of shipping damage Th...

Page 8: ...FROM MICROWAVE RADIATION FIRE ELECTRICAL SHOCK AND OTHER HAZARDS WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER S SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM NOTICE SINCE THIS IS A BASIC SCHEMATIC DIAGRAM THE VALUES OF COMPONENTS AND SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT ...

Page 9: ... is applied to the magnetron to heat the magnetron filament through two noise preventing choke coils A high 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 DOOR IS ...

Page 10: ...er which 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...

Page 11: ...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 12: ...the ambient temperature is 5 K The microwave power output P in watts is calculated from the following formula 4187 x T T is measured while the microwave generator is operating at full power Magnetron filament heat up time is not included about 3 sec The water is stirred to equalize temperature throughout the vessel prior to measuring the final water temperature Stirring devices and measuring instr...

Page 13: ... be sure to check that the primary switch monitor switch and secondary switch operate normally 2 After replacing the door check for microwave energy leakage with a survey meter Microwave energy must be below the limit of 5 mW cm with a 275 ml water load 3 When mounting the door assembly to the oven assembly be sure to adjust the door assembly parallel to the chassis Also adjust so the door has no ...

Page 14: ...R DUCT ASSEMBLY REMOVAL 1 Disconnect the leadwire from lamp 2 Remove the mounting screw to Latch Board J MAGNETRON REMOVAL 1 Disconnect the leadwire from the high voltage transformer 2 Carefully remove the mounting screws holding the magnetron to 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 does not hit ...

Page 15: ...en 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 BOARD TO THE OVEN ASSEMBLY Mount the latch board to the oven assembly Adjust the latch board in the arrow directi...

Page 16: ...er 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 open conditio...

Page 17: ...LTS 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 Filam...

Page 18: ... 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 19: ... 8 sec 14 sec 4 10 sec 12 sec 5 12 sec 10 sec 6 14 sec 8 sec 7 16 sec 6 sec 8 18 sec 4 sec 9 20 sec 2 sec 10 22 sec 0 sec Normal A B Approx 65 80 ohm B C Approx 10 30 ohm A C Approx 85 105 ohm Abnormal Infinite or several ohm Normal Approx 100 150 ohm 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 ...

Page 20: ...ng many plug into one plug outlet and using them at the same time blown fuse or breaker 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 occur Inconsistent intensity of microwave by their characteristics 1 Use plastic wrap or lid 2 Stir once or twice while cooking s...

Page 21: ...imary 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 Continuity Malfunction of secondary switch Replace fuse primary monitor secondary switches and timer switch No continuity Check continuity of secondary switch with door opened 2 Fuse does not blow No continuity Continuity No continuity Defect...

Page 22: ...lable Minimum 8 5 C temperature rise is normal condition CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 of rating voltage Normal Abnormal Measure the output power Defective magnetron Replace magnetron Decrease in power source voltage with load Suggest customer contact local electric power utility co or qualified electrician Check the power source voltage ...

Page 23: ...gh voltage capacitor Normal Check high vol tage capacitor Abnormal Defective high voltage diode Replace high voltage diode Normal Check high vol tage diode Abnormal Defective magnetron Replace magnetron Check magnetron TROUBLE 3 No microwave oscillation even though oven lamp and fan motor run NOTE Make sure the wire leads are in the correct position When removing the wire leads from the parts be s...

Page 24: ...6 1 INTRODUCTION EXPLODED VIEW DOOR LATCH BOARD CONTROL PANEL INTERIOR BASE PLATE OUTER CASE EV ...

Page 25: ...6 2 DOOR PARTS 13552A 13213A 13581A 13720D 14970A 14026A 13536A 13352A EV ...

Page 26: ...6 3 24781T 23572A 24510L 250201 24970A 249401 26549T WTT021 CONTROL PANEL PARTS EV ...

Page 27: ...6 4 OVEN CAVITY PARTS 33390G 35889A WTT021 33112U WTP013 36549S 33052A 948502 34960A EV ...

Page 28: ...6 5 SUCTION GUIDE PARTS 466001 466003 WTT028 466001 43500A 56912B 55262A 43501A WSZ085 EV ...

Page 29: ...6 6 INTERIOR PARTS 568771 56930V 56411A 54974S 56549F WTT037 WTT028 WSZ002 55900A 56324A WSZ062 WSZ002 55006F 50FZZA 34930W EV ...

Page 30: ...6 7 BASE PLATE PARTS 56170D 63302A 63303A WTT021 WSZ002 948501 65006B 65006B 50CZZH WSZ002 54810C 56851D EV ...

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