LG GoldStar GMS-1120TW Service Manual Download

Page: 24 / 33

5-14

CONDITION

CHECK

RESULT

CAUSE

REMEDY

1. Setting time

does not count
down when
touching START
pad.

2. Fan motor or

oven lamp do
not turn on.

No continuity.

Continuity.

Continuity

Defective PCB
assembly.

Loose connection.

Replace PCB
assembly.

Connect them
tightly.

No continuity

Abnormal

Check fan motor.

Defective fan motor.

Replace fan motor.

Abnormal

Normal

Check oven lamp.

Defective oven lamp.

Replace oven lamp.

Defective
secondary switch.

Replace
secondary switch.

Check continuity
of secondary
switch (with
door closed).

Check the con-
nection between
CN1 connector
and PCB
assembly.

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired

program times are set and START pad is touched.

(TROUBLE 4) Oven seems to be operating but little heat is produced in oven load.

NOTE : Simple test of power output-conducted by heating one liter water for one min. if available.

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

Defective PCB
assembly.

Replace PCB
assembly.

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.

Disconnect the
wire leads from
relay 2 and
check on and off
time with
multitester.

Summary of Contents for GoldStar GMS-1120TW

Page 1: ...SERVICE MANUAL MODEL GMS 1120TW CAUTION BEFORE SERVICING THE UNIT READ THESAFETY PRECAUTIONS IN THIS MANUAL website http www lgservice com e mail http www lgeservice com techsup html P NO 3828W5S2299 Printed in Korea ...

Page 2: ...eration 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 de...

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: ...l microwave power IEC60705 2 450 MHz 2M246 0 99 min 99 sec 201 8 W x 12 H x 155 16 D 137 8 W x95 16 H x 143 16 D 33 lbs approx 35 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 ...

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: ...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: ...a 10 oz frozen entrée without entering a cook power or time 8 ONE TOUCH PIZZA Touch this pad to heat up to 3 slices of regrigerated pizza without entering a cook power or time 9 AUTO DEFROST Touch this pad to meat poultry or steaks chops by entering a weight 10 CLOCK Touch this pad to enter the time of day 11 NUMBER PADS Touch number pads to enter cooking time power level quantities or weights 12 ...

Page 8: ... clock 3 EZ ON 4 ONE TOUCH COOKING NOTE Heat only 1 package at a time 5 TIME COOKING 6 MULTI STAGE COOKING 7 AUTO DEFROST COOKING 8 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch the pad Touch and hold pad LOCK appear on the display TO CANCEL CHILD LOCK Touch the pad Touch and hold pad LOCK disappears on the display STOP CLEAR CLOCK NUMBER STOP CLEAR POPCORN STOP CLEAR EZ on...

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: ...ately 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 aver...

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: ...on The 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 al...

Page 13: ... 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 instruments are selected in order...

Page 14: ...lacing the door 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 4 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 t...

Page 15: ...elow the limit of 5 mW cm 2 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 H REMOVING THE TURNTABLE MOTOR 1 Remove the turntable and rotating ring 2 Lay the unit down on its back 3 Remove the turntable motor cover The turntable b...

Page 16: ...RLOCK SYSTEM 1 INTERLOCK MECHANISM The door lock mechanism is a device which has been 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 Mou...

Page 17: ...losed 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 open...

Page 18: ...inding 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 0 2 0 4 ohm Approx 60 90 ohm Less than 1 ohm Normal Infinite Normal Infinite Normal Less than 1 ohm Normal Infinite FILAMENT WINDING PRIMARY TERMINAL FILAMENT WINDING PRIMARY TERMINAL FILAMENT WINDING PRIMARY TERMINAL ...

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: ...ec 2 6 sec 16 sec 3 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 Approx 85 100 ohm B Approx 10 25 ohm Abnormal Infinite or several ohms 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 LEADS...

Page 21: ...s panel to discharge any static charge built up in your body Micom model only CONDITION Microwave oven does not work Inserting many plugs into one 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 Inc...

Page 22: ... does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished 5 12 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 tightly Check the conn ection b...

Page 23: ...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 Continuity Malfunction of secondary switch Replace fuse primary monitor secondary switches and RELAY RY2 of P C B Assembly No continuity Check continuity of secondary switch with door opened 2 Fuse does not blow No continuity Continuity ...

Page 24: ...ws all figures set but oven does not start cooking while desired program times are set and START pad is touched TROUBLE 4 Oven seems to be operating but little heat is produced in oven load NOTE Simple test of power output conducted by heating one liter water for one min if available Minimum 8 5 C temperature rise is normal condition CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 ...

Page 25: ... relay 2 and check continuity relay 2 Operate the unit Abnormal Defective high voltage capacitor Replace high 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 5 No microwave oscillation even though oven lamp and fan motor run...

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

Page 27: ...6 2 DOOR PARTS 13581A 13720D 13352A 13213A 13552A 15006A 13536A 14026A 14970A EV ...

Page 28: ...6 3 24781M 23506A 23572A 23550D 24510L 24970A 250201 268711 WTP018 CONTROLLER PARTS EV ...

Page 29: ...6 4 OVEN CAVITY PARTS 33112U WTT021 WTT010 33390G 35889A WTP013 36549S 33052A EV ...

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

Page 31: ...1A 56201A 56549A 54974S 55900A 56851D 54810C 948502 948503 56201B 56324A 55262A 54912B 34930W 50FZZA 50CZZH WSZ002 WSZ002 WSZ002 WSZ002 WSZ002 WSZ002 WSZ002 WTT028 WTT037 WTT028 WSZ002 948504 56930V INTERIOR PARTS EV ...

Page 32: ...6 7 56170D WTT021 63302A WSZ002 948501 WTT028 647781 63303A BASE PLATE PARTS EV ...

Page 33: ......

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