Goldstar MA2120B Service Manual Download Page 19 | Manualshive

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5-9

COMPONENTS

TEST PROCEDURE

RESULTS

HIGH VOLTAGE
CAPACITOR

HIGH VOLTAGE
DIODE

NOTE :
Some inexpensive meters
may indicate infinite
resistance in both direction.

Measure the resistance.
(Ohm-meter scale: Rx1000)
• Terminal to terminal.

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)

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 sure that the gasket is in good condition.

Antenna

Gasket

Chassis

Filament

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Summary of Contents for MA2120B

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MA2120B MA2120W CAUTION BEFORE SERVICING THE UNIT READ THESAFETY PRECAUTIONS IN THIS MANUAL website http biz lgservice com ...

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: ...3 wire grounded 1 200 Watts full microwave power IEC60705 2 450 MHz 2M282J 0 99 min 99 sec 237 8 W x 139 16 H x 1813 16 D 171 2 W x11 H x 181 2 D 42 lbs approx 46 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 Me...

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: ...sed to set for time of day cooking time power level or defrost weight 7 TIME You can set the desired cook time 8 CLEAR It used to stop oven and clear all entries except time of day 9 START PAUSE This feature turns the oven on instantly 10 DISPLAY WINDOW 11 CLOCK It is used to set the time of day 12 TIMER You can use the timer function of your oven for purpose other than cooking 13 POWER You can se...

Page 8: ...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 and hold 0 pad LOCKED appears on the display TO CANCEL CHILD LOCK Touch and hold 0 pad LOCKED disappears 9 MORE LESS The cook time is adjustable by MORE pad or LESS pad CLEAR CLOCK NUMBER CLEAR POPCORN CLE...

Page 9: ...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 RD PRIMARY SWITCH WH WH BL WH YL MAGNETRON H V CAPACITOR H V DIODE FUSE AC 120V 60Hz L N MICOM CONTROLLER F M TRANSFORMER H V T T M O L PT1 6 5 3 1 BK BK BK PK GN GN BN SECONDARY SWITCH THERMOSTAT OVEN LAMP MONITOR SWITCH...

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: ...ion leakage MEASURING MICROWAVE ENERGY LEAKAGE Pour 275 15cc of 20 5 C 68 9 F water in a beaker 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 Ope...

Page 12: ... 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 cause probe damage RECORD KEEPING AND NOTIFICATION...

Page 13: ... 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 t...

Page 14: ... door NOTE 1 After replacing 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 ch...

Page 15: ...5 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 base cover is easily removed by pinchi...

Page 16: ...K 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 Mount the latch board to t...

Page 17: ... 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 condition When the door is...

Page 18: ...EDURE 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 Rx...

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: ... 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 Inco...

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: ... 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...

Page 25: ... 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 Displ...

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

Page 27: ...6 2 13552A 13213A 13352A 13581A 13720D 13806D 14970A 14026A 13536A DOOR PARTS ...

Page 28: ...6 3 24781M 23506A 23572A 268711 WTP018 23550D CONTROLLER PARTS ...

Page 29: ...6 4 33390G WTT020 WTT010 WSZ185 33112U 35889A 33052M 340511 36549S WTP013 For Model MA2120B For Model MA2120W OVEN CAVITY PARTS ...

Page 30: ...6 5 56912B 43500A 44510A 466003 466001 466002 55262A 43501A WSZ085 LATCH BOARD PARTS ...

Page 31: ...6 6 568771 WSZ002 WSZ002 WSZ002 WSZ002 WSZ002 WTT028 56411A 56930V 50FZZA 55006F 56549F 54974S WTT037 55900A 56324A 54810C WTT028 50CZZH 56851D WSZ002 35012A 34930W 34810M WSZ002 INTERIOR PARTS ...

Page 32: ...6 7 63302L 63303L 65006B 948501 63302R 56170D WSZ002 WTT021 63303R BASE PLATE PARTS ...

Page 33: ...ATOR R 35889A 5889W2A011B ROTATING RING ASSEMBLY R 36549S 6549W1S011A MOTOR CIRC SYNCHRONOUS R 6549W1S015A 43500A 3500W1A013A BOARD LATCH R 43501A 3501W1A016M BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 6600W1K004C SWITCH MICRO R 3B73362E 466001 6600W1K004C SWITCH MICRO R 3B73362F 466003 6600W1K004B SWITCH MICRO R 3B73361D 466003 6600W1K004B SWITCH MICRO R 3B73361E 50CZZH 0CZZW1H002J ...

Page 34: ...3302L 3302W0A014A BASE PLATE R 63302R 3302W1A046B BASE PLATE R 63303L 3303W0A010A BASE PLATE ASSEMBLY R 63303R 3303W1A040B BASE PLATE ASSEMBLY R 65006B 5006W3A016B CAP BASE PLATE R 948501 3B72245D CUSHION R WSZ002 1SBF0402418 SCREW TAP TITE S BINDING HEAD R WSZ085 4B70188C SCREW DRAWING R WSZ185 1SZZW2A002A SCREW DRAWING R WSZ196 1SZZW2A001B SCREW DRAWING R WTP013 1TPL0402418 SCREW TAPPING PAN HEA...

Page 35: ...ASSEMBLY R 34930W 4930W3B029A HOLDER WIRE R 35012A 5012W3A020C INSULATOR R 35889A 5889W2A014A ROTATING RING ASSEMBLY R 36549S 6549W1S011B MOTOR CIRC SYNCHRONOUS R 6549W1S017A 36549S 6549W1S011B MOTOR CIRC SYNCHRONOUS R 6549W1S015A 43500A 3500W1A028A BOARD LATCH R 44510A 4510W3A012B LEVER R 466001 6600W1K004C SWITCH MICRO R 6600W1K001D 466001 6600W1K004C SWITCH MICRO R 6600W1K003D 466003 6600W1K004...

Page 36: ...ASE PLATE ASSEMBLY R 63303R 3303W1A040E BASE PLATE ASSEMBLY R 65006B 5006W3A019A CAP BASE PLATE R 948501 3B72244T CUSHION R WSZ002 1SBF0402418 SCREW TAP TITE S BINDING HEAD R WSZ085 4B70188C SCREW DRAWING R WSZ185 1SZZW2A002A SCREW DRAWING R WTP013 1TPL0402418 SCREW TAPPING PAN HEAD R WTP018 1TPL0402818 SCREW TAPPING PAN HEAD R WTT020 1TTL0402416 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW...

Page 37: ...LDER WIRE R 35012A 5012W3A020A INSULATOR R 35889A 5889W2A011B ROTATING RING ASSEMBLY R 36549S 6549W1S011A MOTOR CIRC SYNCHRONOUS R 6549W1S015A 43500A 3500W1A013A BOARD LATCH R 43501A 3501W1A016M BOARD ASSEMBLY LATCH R 44510A 4510W4A005A LEVER R 466001 6600W1K004C SWITCH MICRO R 3B73362E 466001 6600W1K004C SWITCH MICRO R 3B73362F 466003 6600W1K004B SWITCH MICRO R 3B73361D 466003 6600W1K004B SWITCH ...

Page 38: ...1C THERMOSTAT R 6930WRT002C 63302L 3302W0A014A BASE PLATE R 63302R 3302W1A046B BASE PLATE R 63303L 3303W0A010A BASE PLATE ASSEMBLY R 63303R 3303W1A040B BASE PLATE ASSEMBLY R 65006B 5006W3A016B CAP BASE PLATE R 948501 3B72245D CUSHION R WSZ002 1SBF0402418 SCREW TAP TITE S BINDING HEAD R WSZ085 4B70188C SCREW DRAWING R WSZ185 1SZZW2A002A SCREW DRAWING R WSZ196 1SZZW2A001B SCREW DRAWING R WTP013 1TPL...

Page 39: ...ASSEMBLY R 34930W 4930W3B029A HOLDER WIRE R 35012A 5012W3A020C INSULATOR R 35889A 5889W2A014A ROTATING RING ASSEMBLY R 36549S 6549W1S011B MOTOR CIRC SYNCHRONOUS R 6549W1S017A 36549S 6549W1S011B MOTOR CIRC SYNCHRONOUS R 6549W1S015A 43500A 3500W1A028A BOARD LATCH R 44510A 4510W3A012B LEVER R 466001 6600W1K004C SWITCH MICRO R 6600W1K001D 466001 6600W1K004C SWITCH MICRO R 6600W1K003D 466003 6600W1K004...

Page 40: ...ASE PLATE ASSEMBLY R 63303R 3303W1A040E BASE PLATE ASSEMBLY R 65006B 5006W3A019A CAP BASE PLATE R 948501 3B72244T CUSHION R WSZ002 1SBF0402418 SCREW TAP TITE S BINDING HEAD R WSZ085 4B70188C SCREW DRAWING R WSZ185 1SZZW2A002A SCREW DRAWING R WTP013 1TPL0402418 SCREW TAPPING PAN HEAD R WTP018 1TPL0402818 SCREW TAPPING PAN HEAD R WTT010 1TTG0402422 SCREW TAPPING TRUSS HEAD R WTT021 1TTL0402418 SCREW...

Page 41: ...8 1 SCHEMATIC DIAGRAM OF P C B ...

Page 42: ...8 2 PRINTED CIRCUIT BOARD ...

Page 43: ...023A DIODE SWITCHING 1N4148 SINBLE TP26 DO35 75V 300MA 500MA 4NSEC 5UA R D5 0DSSB00083A DIODE SWITCHING 1N4148M SINBLE TP26 DO34 50V 300MA 500MA 4NSEC 5UA R D80 0DSSB00083A DIODE SWITCHING 1N4148M SINBLE TP26 DO34 50V 300MA 500MA 4NSEC 5UA R D81 0DSSB00083A DIODE SWITCHING 1N4148M SINBLE TP26 DO34 50V 300MA 500MA 4NSEC 5UA R D82 0DSSB00023A DIODE SWITCHING 1N4148 SINBLE TP26 DO35 75V 300MA 500MA 4...

Page 44: ...8 RESISTOR FIXED METAL FILM 22K OHM 1 4 W 1 TA26 R R81 0RD0102F608 RESISTOR FIXED CARBON FILM 10 OHM 1 6 W 5 TA26 R R82 0RN1802F408 RESISTOR FIXED METAL FILM 18K OHM 1 6 W 1 TA26 R R83 0RN5602F408 RESISTOR FIXED METAL FILM 56K OHM 1 6 W 0 01 TA26 R R84 0RN2202G408 RESISTOR FIXED METAL FILM 22K OHM 1 4 W 1 TA26 R R85 0RD0102F608 RESISTOR FIXED CARBON FILM 10 OHM 1 6 W 5 TA26 R R86 0RN1802F408 RESIS...

Page 45: ...P NO 3828W5S2170 Jan 2004 Printed in Korea ...

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