LG MB-4334B, Service Manual

Page 1: ...E OVEN SERVICE MANUAL MODEL MS 2344B MS 2544B CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO 3828W5S4281 November 2004 Printed in Korea 삼 흥 정 판 ...

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 14 0 kg approx 16 0 kg approx 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 tray Rotating ring 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavit...

Page 5: ...tron 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 danger in ordinary use extreme care should be taken du...

Page 6: ...to prevent interference 8 Do not touch the front glass during or after cooking of the Grill and Combination mode This glass is very hot during heater operating 9 Do not operate the oven at microwave and combination mode with 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 is imperative therefore...

Page 7: ...d to cook food for a desired time 4 QUICK DEPROST Used to select the auto weight defrost 5 CLOCK Used to set the time of day 6 STOP CLEAR Used to stop over and clear all entries except time of day 7 AUTO COOK Used to cook the foods listed by one touch 8 AUTO REHEAT Used to select the auto reheat 9 AUTO DEFROST Used to select the auto weight defrost 10 MORE LESS Used to change the cooking time desi...

Page 8: ...entered or to the clock 3 QUICK START 4 MICROWAVE COOKING 5 MULTI STAGE MICROWAVE COOKING 1ST STAGE 2ND STAGE 6 AUTO DEFROST COOKING 7 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch the pad Touch STOP pad L appear in the display TO CANCEL CHILD LOCK Touch the pad touch STOP pad L disappears 8 AUTO COOK 9 QUICK MENU 4 2 STOP CLOCK CLOCK NUMBER START STOP AUTO COOK START STOP ...

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

Page 10: ... high voltage of approximately 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 applie...

Page 11: ...hich is graduated to 600 cc and place the beaker on the center of the turntable Set the energy leakage monitor to 2450 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: ...perature is 5 K The microwave power output P in watts is calculated from the following formula 4187 X T 0 55 X T2 T0 X M T T2 Temperature after heating T0 Temperature after bown M Weight of bowl 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 ...

Page 14: ... 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 gu...

Page 15: ... 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 Rotating Ring 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base cover...

Page 16: ...LATION 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 les than 0 5 mm 1 64 inch Don t push the door release button whil...

Page 17: ...s 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 o...

Page 18: ...S TEST PROCEDURE 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 met...

Page 19: ...r 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 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...

Page 20: ...ERFORMED 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 Normal 350 450 Ω Abnormal or several Ω Normal Approx 16 K Abnormal or several Ω POWER LEVEL 20 40 60 80 100 6 sec 10 sec 14 sec 18 sec 22 sec 16 sec 12 sec 8 sec 4 sec 0 sec Measure the resistance Ohm meter s...

Page 21: ... 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 22: ...ot turn on when the timer knob is pushed with door closed 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 the display are not lighting 5 Display indicates a number different from one touched for example key...

Page 23: ...nuity of magnetron thermostat No continuity 1 Fuse blows Continuity Malfunction of the monitor switch Replace primary and monitor switches Check continuity of monitor switch with door closed Check continuity of primary switch with door opened No continuity Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit No continuity Continuity Sho...

Page 24: ...Loose connection Connection then tightly 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 Abnormal Abnormal Abnormal Defective magnetron Replace magnetron Def...

Page 25: ...eck high vol tage transformer Abnormal Normal Defective circuit protector Replace circuit protector Check circuit protector Abnormal Defective high voltage capacitor Replace high voltage capacitor Check high vol tage capacitor Normal Abnormal Defective high voltage diode Replace high voltage diode Check high vol tage diode Normal Abnormal Defective magnetron Replace magnetron Check magnetron Norma...

Page 26: ...heck continuity relay 2 Operate the unit TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run Display operates properly 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 ...

Page 27: ...OOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS 6 1 EXPLODED VIEW INTRODUCTION MODEL MS 2344B MS 2544B EV Check the Rating Model No MS 2344B MS 2344B 01 ...

Page 28: ...6 2 13552A 14890A 13213A 13720D 14026A 14970A WTT028 13581A 13536A 13650A DOOR PARTS EV ...

Page 29: ...6 3 268711 24781S WTP013 23572A 23790D 23506A CONTROL PANEL PARTS EV ...

Page 30: ...6 4 WTT011 33052M 36549S 33390G 34370T 35889A 33112U WTP013 WTT010 OVEN CAVITY PARTS EV ...

Page 31: ...6 5 466001 466003 WSZ085 466001 43500A 43501A 44510A LATCH BOARD PARTS EV ...

Page 32: ...Z062 56411A 50FZZA 56549F 56201A WTT028 WSZ002 54974S WTT037 55900A 50CZZH WSZ002 WTT028 54810C WSZ002 56912B 55262A 948501 56324A WSZ002 WTP004 56851D 34930W For model MS 2544B Check the Rating Model No INTERIOR PARTS EV ...

Page 33: ...6 7 56170D 63303A WSZ002 WTT021 63302A 65006B BASE PLATE PARTS EV ...

Page 34: ... 36 ...