LG MC-924JL Service Manual Download | Manualshive

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PRINTED CIRCUIT BOARD

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Summary of Contents for MC-924JL

Page 1: ...WAVE GRILL CONVECTION OVEN SERVICE MANUAL MODEL MC 924JL CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL P NO 3828W5S1786 Feb 2001 Printed in Korea website http biz lgservice com ...

Page 2: ...or 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 defective or misadjus...

Page 3: ...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 8 COMPONENT TEST PROCEDURE 5 9 TROUBLE SHOOTING GUIDE 5 14 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 SCHEMATIC DIAGRAM OF P C B 8 1 PRINTED CIRCUIT BOARD 8 2 PCB PARTS LIST ...

Page 4: ...W X 276 H X 387 D Net Weight 23 5kg Shipping weight 26kg Control Complement Microwave Power for Variable Cooking Power level HIGH Full power throughout the cooking time 100 MED HIGH approx 80 of Full power MEDIUM approx 60 of Full power DEFROST approx 40 of Full power LOW approx 20 of Full power Convection Max 250 C Grill Combination Name Plate Location Accessories Owner s manual Glass tray Rotati...

Page 5: ... 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 appliance Though it is free from danger in ordinary use extreme care should be taken during re...

Page 6: ...nto a 15A outlet 9 Do not touch the front glass during or after cooking of the Grill Convection and Combination mode This glass is very hot during heater operating 10 Do not operate oven at microwave and combination mode with the Convection rack or Grill rack placed in the cavity when the oven is empty Earthing Instructions This microwave oven is designed to be used in a fully earthed condition It...

Page 7: ...ISPLAY WINDOW Used to show Time of day Cooking of day Cooking power level Cooking category 9 COMBINATION To select combination cooking 10 CONVECTION To select convection cooking 11 AUTO WEIGHT DEFROST To select auto weight defrost 12 CLOCK To set the time of day 13 TIME To set cooking times 14 START QUICK START To quickly set the cooking time directly Glass tray Rotating ring Metal tray Convection...

Page 8: ...tart Stop Clear Grill Desired cooking time Desired cooking time Start Stop Clear Stop Clear Touch and Hold Stop Clear Stop Clear Touch and Hold Stop Clear Start Stop Clear More Less Desired auto cook Stop Clear Stop Clear Desired defrost category Food weight Start Stop Clear Desired auto roast category Food weight Start Stop Clear Desired auto cook category Food weight Start Desired power level 20...

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

Page 10: ...nsformer which is increased by the action of the diode and charging of the high voltage capacitor The negative D C voltage is then applied to the filament of the magnetron WHEN THE DOOR IS OPEN DURING COOKING Both primary switch and secondary switch open to cut off the primary winding voltage to the high voltage transformer to stop microwave oscillation Turntable and fan motor stop As the door is ...

Page 11: ...ts in customer s home EQUIPMENT Microwave Survey Meter 600cc glass beaker Glass thermometer 100 C NECESSARY MEASURING INSTRUMENTS TESTER VOLTS DC AC Multmeter Microwave survey meter Holaday H1 1500 Hi 1501 Narda 8100 8200 Inch scale 600 cc non conductive material beaker glass or plastic inside diameter approx 8 5cm 31 2 in Cylindrical and made of borosilicate glass vessel max thickness 3mm outside...

Page 12: ...han 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: ...e the screws from the rear and side section The out case must be moved backward to the lifted off B POWER SUPPLY CORD 1 Remove the out case 2 Disconnect two terminals from the noise filter assy and remove one screw of the earth terminal CAUTION DISCHARGE HIGH VOLTAGE CAPACITOR BEFORE SERVICING refer to page 5 C REMOVING CONTROL PANEL ASSEMBLY AND PCB ASSEMBLY 1 Disconnect the leadwire from the PCB...

Page 14: ...lly 2 After replacing the door check for microwave energy leakage with a survey meter Microwave energy must be below the limit of 4 mW cm2 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 play between the inner door surface and oven frame assembly If the door assembly is not mo...

Page 15: ... waveguide 4 Remove the magnetron from the waveguide NOTE 1 When removing the magnetron make it sure dome does not hit any adjacent parts or it may be damaged 2 When replacing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition 3 After replacing the magnetron check for microwave leakage with a survey meter around the magnet...

Page 16: ...and lift it up H OVEN LAMP REMOVAL 1 Disconnect the wire leads from oven lamp 2 Remove one screw securing the Air Duct to the magnetron 3 Push hook to Right and Left of Air Duct with Drive 4 Lift the oven Lamp up I HIGH VOLTAGE TRANSFORMER REMOVAL 1 Disconnect the wire leads from the transformer to the magnetron C Protector ASS Y assembly 2 Remove four screws securing the H V transformer to the ba...

Page 17: ...ate 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 AND SECONDARY SWITCH 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 the oven door will not have any pl...

Page 18: ...the switch The meter should indicate a open condition 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 multimeter leads to the common COM and normally close NC terminal...

Page 19: ...NENTS TEST PROCEDURE RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed 1 Measure the resistance Multi meter scale R X 1 Primary winding Approx 1 4 Ω Secondary winding Approx 90 Ω Filament winding Less than 0 1 Ω 2 Measure the resistance Multi meter scale R X 1000 Primary winding to ground Normal Filament winding to ground Normal MAGNETRON 1 Measure the resistance Wire leads removed Multi meter s...

Page 20: ...orrect position and be sure that the gasket is in good condition Measure the resistance Multi meter scale R x 1000 Terminal to termonal Measure the resistance Multi meter scale R x 1000 Terminal to case Measure the continuity Forward Multi meter scale R x 10000 Measure the continuity Reverse Multi meter scale R x 10000 Normal Abnormal Continuity Normal Continuity Abnormal HIGH VOLTAGE DIODE NOTE S...

Page 21: ...500V 100M Ω insulation resistance meter Measure the resistance Multi meter scale R x 1 Check for continuity of the switch with a Multi meter 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 ...

Page 22: ...pprox 160 Ω Abnormal Infinite or several ohm Normal Approx 200 300 Ω Abnormal Infinite or several ohm Normal Approx 127 ohm Abnormal Infinite or several ohm Normal Approx 13 4 Kohm Abnormal Infinite or several ohm Measure the resistance Multi meter scale R x 1 Measure the resistance Multi meter scale R x 1 Measure the resistance Ohm meter scale R x 1 Measure the resistance Ohm meter scale R x 1000...

Page 23: ...on key board The contacts assignment of the respective pads on the key board is as shown left figures Cooking Start OFF CN2 1 3 5 7 9 Relay 3 Relay 4 Relay 3 Relay 4 Relay 2 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 6 7 8 9 10 11 Membrane Panel P C B Cooking Start OFF NOTE A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE CORRECT...

Page 24: ...eck the primary the secondary and the monitor switches before replacing the fuse CONDITION The fuse blows when power cord is plugged into wall receptacle Shorted lead wise assy or wire hardness Defective monitor switch or out of adjustment Test procedure switches 0 does not appear in displasy window when power cord is first plugged into wall outlet Microwave oven plug is not inserted tightly No po...

Page 25: ...an touch keys Defective tact switch key of P C B Loose connection Connect them tightly Defective secondary switch or out of adjustment Defective tact switch key of P C B Test procedure tact switch key of P C B Test procedure secondary switch Test procedure tact switch key of P C B CAUSE TEST PROCEDURE OR CORRECTION Incorrect touch key Touch key again after closing Loose connection Test tact switch...

Page 26: ... fan motor Food temperature is too low This may not be a defect It is possible that the food should be cooked for a longer period Uneven cooking Inconsistent intensity of microwave by their characteristics Food does not turn during cook cycle Food or cookware extending oven edges of turntable prevents turning rearrange food 1 Wrap the thinner part with aluminum foil 2 Use plastic wrap or with a li...

Page 27: ...n at adequate line voltage Test procedure magnetron Open or loose wiring to above components Blown fuse Check and repair wiring Check fuse Spark occurring Using metallic ware and allowing it to touch the oven wall Ceramic ware trimmed in gold or silver powder is used Do not use any type of cook ware with metallic trimming Do not use metallic ware for cooking except where noted in the cookbook Gril...

Page 28: ...er motor Replace damper motor Check the damper motor Interference Damper open and close at air duct assembly Normal Defective air duct assembly Replace air duct assembly Check the air duct assembly Error message shows in the display Normal Thermistor open or short Replay thermistor Check the thermistor Cook on the glass tray Without metal rack Cook with metal rack Check the Rack Convection indicat...

Page 29: ...TEST PROCEDURE OR CORRECTION Open or loose wire connection to P C B Check and repair wiring Defective relay 3 of P C B Defective grill heater element Test procedure grill heater Test procedure relay 3 of P C B TROUBLE 5 Oven does not operating Grill cooking NOTE MAKE SURE THE WIRE LEADS CORRECT POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR AND NOT THE WIRES WH...

Page 30: ...INTRODUCTION 6 1 EXPLODED VIEW DOOR PARTS CONTROL PANEL PARTS BASE PARTS INTERIOR PARTS OVEN CAVITY PARTS LATCH BOARD PARTS EV MODEL MC 924JL ...

Page 31: ...13581A 13552A 15006A 13213A 14890A 13551A 13650A 14970A 14026A WTP013 6 2 DOOR PARTS EV ...

Page 32: ...6 3 CONTROL PANEL PARTS 24781M 26638A 23551A 268711 WTP015 EV ...

Page 33: ...33112U WTT021 WTT020 35301A 348101 35300A 348102 33550H WMT002 35889A 33390G 33390M 35026G 35026C WTP013 36549S 34370T 33052M 35264A WTT021 WSZ092 EV 6 4 OVEN CAVITY PARTS ...

Page 34: ...6 5 LATCH BOARD PARTS 43500A 43501A 466001 44510A 466003 466001 WTP007 466001 WTT028 WTT028 WTP013 56912B 55262A 53550L 54810U 36549W WSZ085 56930V EV ...

Page 35: ... 50FZZA 55900N 54810S 56322A WTT022 56411A 53504A 53300G 54350S 349801 WTT022 36549C 56201A 56549F 54974S 55900A WTT034 WTP015 WNH002 WSZ059 WNH003 WWP008 WWS005 568772 33808A WMT002 348105 348103 55300S 55900C 348104 WSZ002 WTT021 56208A WTT028 WSZ002 WSZ002 56201B EV ...

Page 36: ...6 7 BASE PLATE PARTS 63303A 56170D 63302A 65006B WTT021 WSZ002 EV ...

Page 37: ...SCHEMATIC DIAGRAM OF P C B 8 1 ...

Page 38: ...PRINTED CIRCUIT BOARD 8 2 ...

Page 39: ......

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