LG GoldStar MA1152B Service Manual Download

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MICROWAVE OVEN

SERVICE MANUAL

MODEL: MA1152W

MA1152B

CAUTION

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

Website http://us.lgservice.com

P/NO : 3828W5S5106

January, 2005

Printed in Korea

Summary of Contents for GoldStar MA1152B

Page 1: ...CROWAVE OVEN SERVICE MANUAL MODEL MA1152W MA1152B CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http us lgservice com P NO 3828W5S5106 January 2005 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: ...4 1 OPERATING 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 12 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 ...

Page 4: ...5 2 lbs approx Touch Control System Clock 1 00 12 59 Microwave Power for Variable Cooking Power level HIGH Full power throughout the cooking time 9 Saute approx 90 of Full power 8 Reheat approx 80 7 Med High approx 70 6 Medium approx 60 5 Med Low approx 50 4 Defrost approx 40 3 Low approx 30 2 Simmer approx 20 1 Warm approx 10 Owner s manual Glass turntable Roller Rest ITEM Model Power Requirement...

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 from...

Page 6: ...nal 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 interference GROUNDING INSTRUCTIONS For personal safety this appliance must be fully grounded at a...

Page 7: ... programmed with weight pad 4 NUMBER Used to set for time of day cooking time power level or defrost weight 5 STOP CLEAR Used to stop oven and clear all entries except time of day 6 TIMER You can use the timer function of your oven for purpose other than cooking 7 TIME Used to cook food for a desired time 8 POWER Used to select power level for cooking 9 Ez On Allows you to cook for 30 seconds at 1...

Page 8: ...tered or to the clock 3 Ez On 4 ONE TOUCH COOKING NOTE Heat only 1 package at a time 5 TIME COOKING 6 MULTI STAGE COOKING 1ST STAGE 2ND STAGE 7 AUTO DEFROST COOKING 8 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch the pad Touch and hold 0 pad L appear on the display TO CANCEL CHILD LOCK Touch the pad Touch and hold 0 pad L disappear STOP CLEAR CLOCK CLOCK NUMBER Ez On STOP C...

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

Page 10: ...ximately 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 the a...

Page 11: ...nt openings for microwave leakage Check for microwave leakage after every servicing The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 4 mW cm2 Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NECESSARY MEASURING INSTRUMENTS TESTER VOLTS DC AC Ohmmeter Microwave survey meter Holaday HI 1500 ...

Page 12: ...ed 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 befween 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 probe damage RECORD KEEPING AND NOTIFICA...

Page 13: ...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 instruments are selected in order to minimize addition o...

Page 14: ...he clearance between the door and the oven E HIGH VOLTAGE TRANSFORMER 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 and high voltage capa...

Page 15: ...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 with a slotted screwdriver 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base c...

Page 16: ...ARY 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 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 th...

Page 17: ...tion When the door is 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 c...

Page 18: ...VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed Approx 0 3 0 8 ohm Approx 100 200 ohm Less than 1 ohm Normal Infinite Normal Infinite Normal Less than 1 ohm Normal Infinite PRIMARY TERMINAL SECONDARY TERMINAL WINDING FILAMENT TERMINAL COMPONENTS TEST PROCEDURE RESULTS 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Secondary winding Filament winding 2 Mea...

Page 19: ...ormal Momentarily indicates several ohms and then gradually returns to infinite Normal Infinite Normal Continuity Abnormal Infinite Normal Infinite Abnormal Continuity Measure the resistance Ohm meter scale Rx1000 Terminal to case Measure the continuity Forward Ohm meter scale Rx10000 Measure the continuity Reverse Ohm meter scale Rx10000 HIGH VOLTAGE DIODE NOTE Some inexpensive meters may indicat...

Page 20: ...T POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES Relay 1 Relay 2 A RD B BK C WH Measure the resistance Ohm meter scale R x 1000 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 POWER LEVEL 1 2 3 4 5 6 7 8 9 10 4 sec 6 sec 8 sec 10 sec ...

Page 21: ...tallic ware for cooking except where noted in the cooking guide Do not use any type of cookware with metallic trimming CAUSE REMEDY TROUBLE SHOOTING CAUTIONS 1 Check grounding before checking for trouble 2 Be careful of the high voltage circuit 3 Discharge the high voltage capacitor See page 2 1 4 When checking the continuity of the switches or of the high voltage transformer disconnect one lead w...

Page 22: ...ce key membrane assembly Defective PCB assembly Replace PCB assembly TROUBLE 1 The following visual conditions indicate a probable defective control circuit 1 Incomplete segments Segment missing Partial segment missing Digit flickering NOTE Slight flickering is normal 2 Colon does not turn on or blink 3 A distinct change in the brightness of one or more numbers in display 4 One or more digits in t...

Page 23: ...ntinuity No continuity Malfunction of the monitor switch Replace fuse primary monitor secondary switches and RELAY RY2 of P C B Assembly Check continuity of monitor switch with door closed Continuity No continuity Shorted contact at the primary switch Replace fuse primary monitor secondary switches and RELAY RY2 of P C B Assembly Check continuity of primary switch with door opened Normal Replace f...

Page 24: ... Defective PCB assembly Loose connection Output is low Lower than 90 of rating voltage Normal Decrease in power source voltage with load Suggest customer contact local electric power utility co or qualified electrician Check the power source voltage Disconnect the wire leads from relay 2 and check on and off time with multitester Measure the output power Abnormal Abnormal Normal Defective PCB asse...

Page 25: ...uity relay 2 Operate the unit Defective PCB assembly Replace PCB assembly Replace high voltage transformer Defective high voltage capacitor Replace high voltage capacitor Abnormal normal Check high vol tage transformer Abnormal normal Check high vol tage capacitor Defective high voltage diode Replace high voltage diode Abnormal normal Check high vol tage diode Defective magnetron Replace magnetron...

Page 26: ...OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS LATCH BOARD PARTS CONTROL PANEL PARTS DOOR PARTS 6 1 EXPLODED VIEW INTRODUCTION EV ...

Page 27: ...6 2 DOOR PARTS 13581A 14970A 14026A 13552A 13213A 13352A 13720D 13536A EV ...

Page 28: ...6 3 CONTROLLER PARTS 23506A 23572A 268711 WTP018 24781M EV ...

Page 29: ...6 4 OVEN CAVITY PARTS 33390G 35889A WSZ185 33112U WTP013 36549S 33052A WTT010 WTT020 For model MA1152W For model MA1152B EV ...

Page 30: ...6 5 LATCH BOARD PARTS 466001 466003 WSZ085 466001 43500A EV ...

Page 31: ...INTERIOR PARTS 568771 56930V 56411A WTT028 56324A WSZ002 WTT028 WTT037 50CZZH 54810C 56851D 55900A 56549F 54974S WEB001 WEB001 WSZ002 50FZZA 56201A 54980A 56912B 948503 WSZ002 948501 55262A 948502 948502 EV ...

Page 32: ...6 7 BASE PLATE PARTS 63302A WTT021 WSZ002 56170D EV ...

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