LG Electronics MS3447GR Fuse blows, Check continuity Continuity Monitor Switch with Door closed

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(TROUBLE 2) Oven does not operate at all, Display window does not display any figures, and no input is accepted.

CONDITION

1. Fuse blows.

CHECK

RESULT

Check continuity

Continuity.

of monitor

 

switch (with

 

door closed).

No continuity.

 

Replace fuse

 

CAUSE

Malfunction of the monitor switch.

REMEDY

Replace fuse, primary, monitor, secondary switches, and RELAY(RY2) of P.C.B Assembly.

Check continuity

 

 

 

Continuity.

 

 

of primary

 

 

 

 

 

 

 

 

 

 

 

switch (with

 

 

 

 

 

 

door opened).

 

 

 

No continuity.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Check continuity

Continuity.

of secondary

 

switch (with

 

door opened).

No continuity.

 

Shorted contact at the primary switch.

Malfunction of secondary switch.

Replace fuse, primary, monitor, secondary switches, and RELAY(RY2) of P.C.B Assembly.

Replace fuse, primary, monitor, secondary switches, and RELAY(RY2) of P.C.B Assembly.

Disconnect one

Normal.

side of the wire

 

lead connected

 

from transformer

Fuse blows again

to the high

 

voltage

 

capacitor and

 

operate the unit.

 

Defective high

 

 

Replace high

voltage capacitor.

 

 

voltage capacitor.

 

 

 

 

 

 

 

 

Defective high volt-

 

 

Replace high volt-

age transformer.

 

 

age transformer.

 

 

 

 

NOTE : All these switches must be replaced at the same time. Refer to page 5-7, 5-8

2.Fuse does not blow.

Check continuity

 

 

No continuity.

 

 

Defective

 

 

 

 

 

thermostat.

 

of thermostat.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Continuity.

 

Check continuity

No continuity.

Defective power

of power supply

 

supply cord.

cord.

 

 

 

Replace thermostat.

Replace power supply cord.

LGE Internal Use Only

5-13

Copyright © 2007 LG Electronics. Inc. All right reserved.

 

 

Only for training and service purposes

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Contents Microwave Oven Microwave Radiation Safety PrecautionsContents Approx % SpecificationsFull power throughout the cooking time Approx % of Full powerAntenna Microwave RadiationEarthing Instructions InstallationInstalling Cooking time Features Control PanelOperating Instructions More Pressing More will add 10 seconds to the cooking timeOperating Sequence Schematic Diagram Circuit Description Necessary Tools Service InformationTools and Measuring Instruments Microwave Leakage TestAround the magnetron Waveguide Measurement with Outer Case RemovedMeasurement with a Fully Assembled Oven Control Panel Assembly Measurement of Microwave Power OutputDisassembly and Adjustment Power Supply CordDoor Main Assembly Removal PCB Assembly RemovalVery Carefully AIR Duct Assembly RemovalMagnetron Removal Removing the Turntable MotorInterlock System FAN Motor Assembly RemovalHigh Voltage Transformer Removal High Voltage Capacitor and Diode RemovalSwitches Primary Interlock Switch TestSecondary Interlock Switch Test Monitor Switch TestMagnetron Component Test ProcedureHigh Voltage Transformer Wire leads removed Filament Winding Primary TerminalMeasure the continuity Forward Normal Continuity High VoltageMeasure the resistance Normal Momentarily indicates CapacitorFAN Motor PowerRelay LevelCondition Cause Remedy Trouble ShootingContinuity No continuity Defective PCB assemblyDefective key membrane assembly Defective PCB assembly Some inputs cannot be programmedFuse blows Check continuity Continuity Monitor Switch with Door closedPower supply Replace power supply cordPower source Rating voltage Voltage Normal Disconnect Setting time Check continuitySecondary switch Defective PCB Replace PCB AssemblyReplace high voltage diode Replace magnetron Defective PCB assembly Defective high voltage transformerAbnormal Defective PCB assembly Introduction Exploded ViewDoor Parts Control Panel Parts Oven Cavity Parts Larch Board Parts WTT021 WTP004 56501A 54974T Interior PartsBase Plate Parts

MS3447GR, MS3447GRS specifications

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