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LG MS2548GR, Service Manual

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LG MS2548GR Service Manual Download Page 18

5-8

CAUTIONS

1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE

OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)

2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER

OF WATER IN CONTAINER) IN 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 resistance.

(Ohm-meter scale: Rx1000)
• Filament to chassis

Approx.: 2.5 

Ω

Approx.: 110 

Ω

Less than: 0.4 

Ω

Normal: 

∞

Normal: 

∞

Normal: Less than 1 

Ω

Normal: 

∞

PRIMARY  
TERMINAL

SECONDARY  
TERMINAL

WINDING

FILAMENT

TERMINAL

COMPONENT TEST PROCEDURE

LGE Internal Use Only

Copyright © 2007 LG Electronics. Inc. All right reserved. 
Only for training and service purposes

Summary of Contents for MS2548GR

Page 1: ...RVICE MANUAL MODEL MS2548GR MS2548XR CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http biz lgservice com P NO MFL31039014 February 2009 Printed in Korea 삼 흥 정 판 Internal Use Only ...

Page 2: ... 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 and microwave generation and transmission systems shall ...

Page 3: ...ON 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 LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and s...

Page 4: ...GH 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 Glass tray Rotating ring 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavity Dimensions Net Weight Shipp...

Page 5: ...te 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 during repair THE OVEN IS TO BE SERVICED ONLY BY PROPERLY Q...

Page 6: ... 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 wires in the mains lead of this appliance may not correspond ...

Page 7: ... cooking 7 ADD MINUTE Touch this pad to cook at 100 cook power for 1 minute to 99 minute 59 seconds 8 NUMBER Used to set for time of day cooking time power level or defrost weight 9 SOFTEN Touch this pad to soften ice cream cream cheese butter or frozen juice 10 MELT Touch this pad to melt chocolate cheese butter or marshmallows 11 STOP CLEAR Used to stop over and clear all entries except time of ...

Page 8: ...CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK Touch the Start Q Start pad Touch STOP pad L LO OC C appear in the display TO CANCEL CHILD LOCK Touch the Start Q Start pad Touch STOP pad L LO OC C disappears 4 MICROWAVE COOKING 5 AUTO DEFROST 7 ONE TOUCH AUTO MENU 8 TIME COOKING Stop Clear Clock Clock Set the hour Set the minutes Clock Stop Clear Power Start Time Stop Clear Auto De...

Page 9: ...SCHEMATIC DIAGRAM 4 3 LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...

Page 10: ...d 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 of microwave ov...

Page 11: ...enter 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 radiation monitor by holding the probe perpendicular to the s...

Page 12: ...e 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 probe damage RECORD KEEPING AND NOTIFICATION AFTER MEASU...

Page 13: ...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 measuring the final water temperature Stirring devices an...

Page 14: ...ect 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 guide ASS Y to the oven cavity and remove the high voltage ...

Page 15: ...rowave 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 is easily removed by pinching the six parts with a wire cutting 5 Disconnect the leadwire from the turntabl...

Page 16: ...MBLY 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 while making adjustment Make sure that the latch moves smooth...

Page 17: ... 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 closed meter should indica...

Page 18: ...ads 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 Rx1000 Filament to chassis Approx 2 5 Ω Approx 1...

Page 19: ...rward 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 gasket is in good condition Antenna Gasket Chassis Filam...

Page 20: ...URE 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 Abnormal or several Ω Normal Approx 16 KΩ 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 scale R x 100 Measure the resistance Ohm meter scale R x 1...

Page 21: ...nd 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 foil 2 Use plastic wrap or lid 3 Stir once or twice while ...

Page 22: ... 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 in 5 and 3 appears in the display 6 Specific numbers for...

Page 23: ...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 Shorted contact at the primary switch Replace primary and mo...

Page 24: ...wer 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 Defective P C B assembly Replace P C B assembly Measure the ...

Page 25: ...ircuit 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 Normal TROUBLE 5 No microwave oscillation even though oven lam...

Page 26: ...rowave 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 LGE Internal Use Only Copyright 2007 LG Electronics Inc All right...

Page 27: ...DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS 6 1 EXPLODED VIEW INTRODUCTION EV MODEL ...

Page 28: ... 6 3 13552A 13213A 14026A 14970A 13581A 13536A 13551A DOOR PARTS II EV MODEL ...

Page 29: ... 6 5 268711 24781M 23551A 24510L WTP018 23551B 24970A CONTROL PANEL PARTS II EV MODEL ...

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

Page 31: ... 6 7 466001 466003 WSZ085 466001 43500A 43501A LATCH BOARD PARTS EV ...

Page 32: ... 6 8 568771 56930G WSZ062 56411A 50FZZA 56549F 56201A WTT028 WSZ002 WEB001 54974S WTT037 55900A 50CZZH WTT028 54810C WSZ002 56912B 55262A 948501 56324A WSZ002 WTP004 56851C 34930W INTERIOR PARTS EV ...

Page 33: ... 6 9 56170D 63303A WSZ002 WTT021 63302A WTT030 647781 BASE PLATE PARTS EV ...

Page 34: ... 40 ...

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