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LG MS-3444DPS, Service Manual

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LG MS-3444DPS Service Manual Download Page 24

5-14

(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.

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

No continuity

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

Defective
secondary switch.

Replace
secondary switch.

Defective PCB
assembly.

Replace PCB
assembly.

Check continuity
of secondary
switch (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.

Connect them
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
multitester.

Defective PCB
assembly.

Replace  PCB
assembly.

Decrease in power
source voltage
with load.

Suggest customer
contact local
electric power
utility co. or
qualified
electrician.

Check the
power source
voltage.

Defective
magnetron.

Replace
magnetron.

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.

Summary of Contents for MS-3444DPS

Page 1: ...ICROWAVE OVEN SERVICE MANUAL MODEL MS 3446VR CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO MFL31039001 May 2006 Printed in Korea 삼 흥 정 판 ...

Page 2: ...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 misadjusted components in the interloc...

Page 3: ... 1 OPERATING SEQUENCE 4 2 SCHEMATIC DIAGRAM 4 4 CIRCUIT DESCRIPTION 4 5 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 ...

Page 4: ...ox 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 40 3 Low approx 30 2 Simmer approx 20 1 Warm approx 10 Owner s manual cooking guide Glass turntable Roller rest ITEM MODEL Power Requireme...

Page 5: ... area Proper 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 Unlike other appliances the microwave oven is high voltage and high current equipment Though it is free from...

Page 6: ...lat 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 EARTHING INSTRUCTIONS This microwave oven is designed to be used in a fully earthed condition It is imperative therefore to make sure it is properly earthed before servicing WARNING THIS APPLIANCE MUST BE EARTHED IMPORTANT As the colors of the wire...

Page 7: ...s of cooking time 6 NUMBER These used to set for time of day cooking time power level or defrost weight 7 CLOCK It is used to set the time of day 8 STOP CLEAR It used to stop oven and clear all entries except time of day 9 AUTO REHEAT 10 QUICK DEFROST You can thaw specific foods and weight very quickly 11 AUTO DEFROST This feature provides you with the best defrosting method for frozen foods 12 PO...

Page 8: ...O DEFROST COOKING 6 CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch STOP CLEAR pad Touch and hold STOP CLEAR pad LOCKED appears on the display TO CANCEL CHILD LOCK Touch and hold STOP CLEAR pad LOCKED disappears 7 MORE LESS The cook time is adjustable by MORE pad or LESS pad 8 AUTO REHEAT NOTE Then the oven will start automatically 9 Q DEFROST 10 AUTO COOK NOTE Then the oven ...

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

Page 10: ...s 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 applied signal to vary the average output power...

Page 11: ...ice personnel should instruct the owner not to use the unit until the oven has been brought into compliance If the oven operates with the door open the service personnel should Tell the user not to operate the oven Contact the manufacturer The service personnel should check all surface and vent openings for microwave leakage Check for microwave leakage after every servicing The power density of th...

Page 12: ...st be moved 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 by 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 Hol...

Page 13: ...terial thickness of 3 mm and an outside diameter of approximately 190mm The oven and the empty vessel are at ambient temperature prior to the start of the test The initial temperature T1 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 thd low...

Page 14: ...d push the 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 cm2 with a 275 ml water load 3 When mounting the door assembly to the oven assembly be sure to adjust the door assembly paralle...

Page 15: ... 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 pinching t...

Page 16: ... 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 Mount th...

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: ... THE OVEN COMPONENTS 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...

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: ...ED 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 1 2 3 4 5 6 7 8 9 10 4 sec 6 sec 8 sec 10 sec 12 sec 14 sec 16 sec 18 sec 20 sec 22 sec 18 sec 16 sec 14 sec 12 sec 10 sec 8 sec 6 sec 4 sec 2 sec 0 sec POWER LEVEL Relay 2 A B Measure the resistance Ohm meter scale R x 1 Check for continui...

Page 21: ...ug 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 Inconsistent intensity of microwave by their characteristics 1 Use plastic wrap or lid 2 Stir once or twice while cooking soup cocoa or milk etc Uneven cooking Ceramic ware trimmed in gold or silver powder is used Avoid using ot...

Page 22: ...light does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished TROUBLE 1 The following visual conditions indicate a probable defective control circuit CONDITION CHECK RESULT CAUSE REMEDY Everything works as specified Continuity No continuity Still have trouble Defective key membrane assembly Defective PCB assembly Loose connection Defective PCB...

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 TROUBLE 2 Oven does not operate at all Display...

Page 24: ...h 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 Connect them 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 m...

Page 25: ...e capacitor Replace high voltage capacitor Check high vol tage capacitor Abnormal Defective magnetron Replace magnetron Check magnetron TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run Display operates properly Output is full power when you set lower power level Abnormal Disconnect the wire leads from relay 2 and check continuity relay 2 Operate the unit Defective PCB ass...

Page 26: ...EXPLODED VIEW 6 1 INTRODUCTION INTERIOR PARTS OVEN CAVITY PARTS DOOR PARTS CONTROL PANEL PARTS BASE PLATE PARTS LATCH BOARD PARTS EV MODEL MS 3446VR ...

Page 27: ...DOOR PARTS 6 2 13552A 13213A 13581A 14970A 14026A 13536A 15006A 13551A EV ...

Page 28: ...CONTROL PANEL PARTS 6 3 23551A 24781M WTP018 268711 24510L 23551B 24970A EV ...

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

Page 30: ...LARCH BOARD PARTS 6 5 WSZ085 466001 466003 466001 43500A 43501A EV ...

Page 31: ... WSZ062 WSZ002 WSZ002 WSZ002 WSZ002 WTT028 WTT028 56411A 56930V 50FZZA 56201A 56549F 54974S WTT037 55900A 54810C WTT028 50CZZH 34930W 56324A 55262A 56912B 56201B 948502 54974T 56501A WTP004 WTT021 WSZ002 56851D 35012A 56901A EV ...

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

Page 33: ...C R 6549W1S017A 43500A 3500W1A018A Holder Locker R 43501A 3501W1A053A Holder Assembly Locker R 466001 6600W1K003D Switch Micro R 6600W1K001D 466001 6600W1K003D Switch Micro R 6600W1K004F 466003 6600W1K003C Switch Micro R 6600W1K001C 466003 6600W1K003C Switch Micro R 6600W1K004E 50CZZH 0CZZW1H001W Capacitor AL Radial R 0CZZW1H004Q 50FZZA 3B74133N Fuse Time Delay R 3B70856K 54810C 4810W4C003B Bracke...

Page 34: ...e R WSZ062 4000W4A003A Screw Customzied R WSZ085 4B70188C Screw Customzied R WTP004 1TPL0302418 Screw Tapping R WTP013 1TPL0402418 Screw Tapping R WTP018 1TPL0402818 Screw Tapping R WTT010 1TTL0402416 Screw Tapping R WTT021 1TTL0402418 Screw Tapping R WTT028 1TTL0402818 Screw Tapping R WTT037 1TTL0403818 Screw Tapping R PART NO DESCRIPTION SVC ALTERNATE R SERVICE PARTS ...

Page 35: ......

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