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5-8

CAUTIONS

1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE

OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)

2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER

OF WATER IN CONTAINER) IN THE OVEN.

COMPONENTS

TEST PROCEDURE

RESULTS

HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)

MAGNETRON
(Wire leads removed)

1. Measure the resistance.

(Ohm-meter scale: Rx1)
• 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.: 1.4 ohm
Approx.: 90 ohm
Less than: 1 ohm

Normal: Infinite
Normal: Infinite

Normal: Less than 1 ohm

Normal: Infinite

PRIMARY
TERMINAL

SECONDARY
TERMINAL

FILAMENT
WINDING
TERMINAL

COMPONENT TEST PROCEDURE

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Summary of Contents for MS-1983ALB

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MS 1983ALB CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO 3828W5S3803 May 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 11 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 CONTENTS ...

Page 4: ...mm 12 0 kg 13 2 kg Microwave Power for Variable Cooking Power level Max Full power throughout the cooking time Med High approx 80 of Full power Medium approx 60 of Full power Defrost approx 40 of Full power Low Warm approx 20 of Full power Owner s manual Glass turntable Roller Rest 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavity Dimension...

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: ...lat 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 interference 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 WARNING THIS APPLIANCE MUST BE EARTHED IMPORTANT As the colors of the wire...

Page 7: ...to weight defrost 4 AUTO COOK MORE Used to select auto cook and increase the cooking time 5 AUTO REHEAT Used to select auto reheat 6 STOP CLEAR Used to stop over and clear all entries except time of day 7 START QUICK START One tap allows over to begin functioning 8 CLOCK Used to set the time of day 9 DIAL Roller Rest Turntable Oven Front Plate Window Door Screen Safety Door Lock System Door Seal C...

Page 8: ...ROWAVE COOKING 5 AUTO DEFROST COOKING 6 QUICK DEFROST COOKING 7 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch the STOP CLEAR pad Touch STOP CLEAR pad L appear on the display TO CANCEL CHILD LOCK Touch the STOP CLEAR pad Touch STOP CLEAR pad L disappears 8 AUTO COOK 9 AUTO REHEAT 10 MULTI STAGE MICROWAVE COOKING 1ST STAGE 2ND STAGE STOP CLEAR CLOCK CLOCK TIME minutes CLOCK T...

Page 9: ...M MICROWAVE RADIATION FIRE ELECTRICAL SHOCK AND 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 BASIC SCHEMATIC DIAGRAM THE VALUES OF COMPONENTS AND SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT ...

Page 10: ...pproximately 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 signal to vary t...

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: ...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 the oven surface this may possibly cause...

Page 13: ... final water temperature and 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 Stirrin...

Page 14: ...R REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from magnetron high voltage transformer and capacitor 3 Remove the screw holding the high voltage transformer to the baseplate F FAN MOTOR ASSEMBLY REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from fan motor noise filter and high voltage capacitor 3 Remove the two screws holding the the suction g...

Page 15: ...t of 5 mW cm2 With a 275 ml water load Make sure that gasket is rigidly attached to the magnetron To prevent microwave leakage tighten the mounting screws properly making sure there is no gap between the waveguide and the magnetron J REMOVING THE TURNTABLE MOTOR 1 Remove the turntable 2 Remove the turntable shaft VERY CAREFULLY 3 Lay the unit down on its back 4 Remove the turntable motor cover The...

Page 16: ...LLATION 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 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 wh...

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: ...EDURE RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 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 19: ...le Rx1000 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 Normal Continuity Abnormal Normal Abnormal Continuity NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gask...

Page 20: ...owave Check for continuity of the fuse with an multi meter Check for P C B connector NOTE If the fuse is blown check the primary the secondary and the monitor switches H V D and H V C before replacing the fuse If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time Replace just the fuse if the switches operate normally Cooking Start OFF Normal A...

Page 21: ...ce Ohm meter scale R x 100 Measure the resistance Ohm meter scale R x 1000 A B C Normal Abnormal or several Ω A B A C 40 60Ω 300 500Ω 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 ...

Page 22: ... 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 thinner part with aluminum f...

Page 23: ...ing 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 13 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 Loo...

Page 24: ...e blows Continuity No continuity Continuity Shorted contact at the primary switch Replace fuse primary monitor switches and RELAY RY2 of P C B Assembly No continuity Normal Defective high voltage capacitor Replace high voltage capacitor Fuse blows again Defective high volt age transformer Replace high volt age transformer Malfunction of the monitor switch Replace fuse primary monitor switches and ...

Page 25: ...h 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 Connect them 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 26: ...lay2 Operate the unit Abnormal Normal Defective circuit protector Replace circuit protector Check circuit protector Normal Normal Abnormal Defective high voltage capacitor Replace high voltage capacitor Check high vol tage capacitor Abnormal Defective high voltage transformer Replace high voltage transformer Check high vol tage transformer Abnormal Defective high voltage diode Replace high voltage...

Page 27: ...mbly NOTE Make sure the wire leads correct position When Removing the wire leads from the parts be sure to grasp the connector not the wires When removing the magnetron be sure to install the magnetron gasket in the correct position and in good condition TROUBLE 6 No microwave oscillation even though oven lamp and fan motor run Display operates properly CONDITION CHECK RESULT CAUSE REMEDY ...

Page 28: ...OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS LATCH BOARD PARTS CONTROL PANEL PARTS DOOR PARTS 6 1 EXPLODED VIEW INTRODUCTION ...

Page 29: ...6 2 13581A 14970A 13650A 13552A 13213A 14890A 13551A 13536A WTT028 14026A DOOR PARTS ...

Page 30: ...6 3 24781M 23551A 23790D 250201 268711 249401 WTP004 CONTROL PANEL PARTS ...

Page 31: ...6 4 33112U 33390G 35889A 36549S 33052A WTT021 WTT020 WTP013 OVEN CAVITY PARTS ...

Page 32: ...6 5 43500A 466001 WSZ085 466003 466001 44510A LATCH BOARD PARTS ...

Page 33: ...6 6 56930V 56324A 56411A 50FZZA 56201A 56549F 54974S 56851D 54810C 56912B 948501 55262A 568771 50CZZH 55900A WSZ002 WSZ062 WSZ002 WTT028 WSZ002 WTT028 WSZ002 WTT037 56901A INTERIOR PARTS ...

Page 34: ...6 7 56170D 63302A 65006B 63303A 948502 WSZ002 WTT021 BASE PLATE PARTS ...

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