LG MS-1947C Service Manual Download Page 26 | Manualshive

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5-16

CONDITION

CHECK

RESULT

CAUSE

REMEDY

No microwave
oscillation.

No continuity.

Continuity.

Defective P.C.B
assembly

Replace P.C.B
assembly

Disconnect the
wire leads from
relay 2 and
check continuity
of relay2.
(Operate the
unit)

Abnormal

normal

Defective high
voltage
transformer.

Replace high
voltage
transformer .

Check H.V.
transformer.

normal

normal

Abnormal

Defective high
voltage Diode.

Replace high
voltage Diode.

Check H.V.
diode.

Abnormal

Defective high
voltage capacitor.

Replace high
voltage capacitor.

Check H.V.
capacitor.

Abnormal

Defective
magnetron.

Replace
magnetron .

Check
Magnetron.

normal

Abnormal

Defective
Protector Diode.

Replace
Protector Diode .

Check
Protector Diode.

(TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run

(Display operates properly)

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Summary of Contents for MS-1947C

Page 1: ...ICROWAVE OVEN SERVICE MANUAL MODEL MS 1947C CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO MFL31039005 May 2007 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 12 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 CONTENTS ...

Page 4: ... approx 13 5 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 turntable Roller rest 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavity Dimen...

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: ...e power level for cooking grill and combi 4 CLOCK Used to set the time of day 5 QUICK DEFROST Used to select the auto weight defrost 6 MORE LESS Used to change the cooking time desired weight 7 COOK TIME Used to cook food for a desired time 8 STOP CLEAR Used to stop over and clear all entries except time of day 9 START QUICK START One tap allows over to begin functioning 2 6 9 3 7 8 4 5 1 ...

Page 8: ...em 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 STOP pad Touch STOP CLEAR pad L appear on the display TO CANCEL CHILD LOCK Touch the STOP pad touch STOP CLEAR pad L disappears 8 AUTO COOK 9 QUICK DEFROST STOP CLOCK CLOCK NUMBER START ST...

Page 9: ...SCHEMATIC DIAGRAM 4 3 6 ...

Page 10: ...A 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 4000 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: ...t 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 is moved horizontally alo...

Page 13: ...erature prior to the start of the test The initial temperature 1 of the water is 10 2 C It is measured immediately before the water is added to the vessel After addition of the water to the vessel the load is immediately placed on the center of the turntable which is in the lowest position and the microwave power switched on The time T for the temperature of the water to rise by a value T of 10 2 ...

Page 14: ... 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 noise filter and high voltage capacitor 3 Remove the two screws holding the th...

Page 15: ... 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 turntable shaft VERY CAREFULLY 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base co...

Page 16: ... 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 than 0 5 mm 1 64 inch Don t push the door release button while making adjustment Mak...

Page 17: ... 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 op...

Page 18: ...EDURE RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 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 Rx1000 Filam...

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 Abnormal Continuity Normal Continuity Abnormal NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the...

Page 20: ...owave Check for continuity of the fuse with an 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 the switches operate normally Check for P C B connector Normal Abnormal 0 C Approx...

Page 21: ...nce Ohm meter scale R x 1000 Normal Abnormal or several Ω Normal Approx 100 200 Ω Abnormal or several Ω NOTE A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED 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 A B C A B A C 40 60Ω 300 500Ω ...

Page 22: ... 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 23: ...ing cooking cycle 11 Display time of day does not reappear when cooking is finished 12 Beep sound is not heard when correct key is touched 5 13 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 Everything works as specified Still have trouble Defective PCB assembly Replac...

Page 24: ...ch with door closed Check continuity 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 TROUBLE 2 Oven does not operate at all Display window does not display any figures and no input is accepted NOTE All these switches must be replaced at the same time Refer to page 5 6 5 7 2 Fuse does ...

Page 25: ...with door closed Check fan motor Check oven lamp Abnormal Abnormal Normal Defective fan motor Defective oven lamp Replace fan motor Replace oven lamp Loose connection Connection then tightly CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 of rating voltage Normal Normal Abnormal Abnormal Measure the output power Disconnect the wire leads from relay 2 and check on and off time with ...

Page 26: ...high voltage transformer Check H V transformer normal normal Abnormal Defective high voltage Diode Replace high voltage Diode Check H V diode Abnormal Defective high voltage capacitor Replace high voltage capacitor Check H V capacitor Abnormal Defective magnetron Replace magnetron Check Magnetron normal Abnormal Defective Protector Diode Replace Protector Diode Check Protector Diode TROUBLE 5 No m...

Page 27: ...e set power level Operates properly on HIGH CONDITION CHECK RESULT CAUSE REMEDY Output is full when you set lower power level Abnormal Disconnect the wire leads from relay 2 and check continuity relay 2 Operate the unit Defective P C B assembly Replace P C B assembly ...

Page 28: ...LATCH BOARD PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS DOOR PARTS CONTROL PANEL PARTS 6 1 EXPLODED VIEW INTRODUCTION EV MODEL MS 1947C ...

Page 29: ...6 2 13536A 13581A 14970A 14026A 13552A 13213A 14890A 13720D DOOR PARTS EV ...

Page 30: ...6 3 23506A 23572A 268711 24781M WTT021 CONTROL PANEL PARTS EV ...

Page 31: ...6 4 33390G WTT021 33112U WTP013 36549S 33052A WTT010 35889A OVEN CAVITY PARTS EV ...

Page 32: ...6 5 466003 466001 43501A 43500A 466001 WSZ085 44510A LATCH BOARD PARTS EV ...

Page 33: ...6 6 WSZ062 56411A 568771 56930V 56324A 50FZZA 56201A 55900A WTT037 56549F WTT028 WSZ002 54974S WSZ002 56851D 50CZZH WTT028 54810C 56912B 55262A WSZ002 56901A 948501 INTERIOR PARTS EV ...

Page 34: ...6 7 56170D 63302A WSZ002 WTT021 65006B 63303A BASE PLATE PARTS EV ...

Page 35: ......

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