LG Electronics LMV1825SBQ, MV1825SW service manual Checkout Procedures for Relay Problem a

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(2) CHECKOUT PROCEDURES FOR RELAY.

- PROBLEM (A) -

FAN motor and oven lamp turn on without touching

START key when the door is closed.

NO

YES

GOOD

Remove the mate connector of I/O CON from the circuit board.

Does the unit still operate?

NO

YES

Replace the circuit board

Defective

RELAY1

Replace

RELAY1

- PROBLEM (B) -

FAN motor and oven lamp turn on When the door is closed and START key is touched.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

NO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GOOD

Measure the voltage at pin NO.

35 of U01

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Voltage reading: 0 Vdc

 

 

 

 

10 of U03

 

 

 

 

 

 

 

 

 

 

Voltage reading: about 15V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Replace the circuit board

Defective

RELAY1 or poor

connection of

RELAY1

Replace

RELAY1 or correct

the connection.

7-19

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Contents Safety Precautions in this Manual Microwave OvenPage Table of Contents Specifications Microwave Radiation Installation Grounding InstructionsOperating Instructions Control PanelControl Panel Instructions Overall Circuit Diagram Schematic DiagramMatrix Circuit for Touch KEY Board General Precautions in USE Features and Specifications FeaturesTrial Operation Precautions and Repair Service Tips PreliminaryMicrowave Leakage Test EquipmentPower Output Measurement Measurement with the Outer Case RemovedDisassembly Instructions Important NotesHOW to Remove the F.P.C. Connector HOW to Insert the F.P.C. ConnectorRemoving the OUT CASEFigure Removing the Door Interlock Switches Figures 9,10 Removing Magnetron Removing Stirrer FAN Removing Door FigureAssembling Door Removing the Ventilation MotorReplacing the Humidity Sensor Removing the Turntable Motor Interlock System Interlock MechanismTest the Latch and Switch Sequence Components Test Procedure Results Interlock Continuity TestTest and Checkout PROCEDURES, and Trouble Shooting Test ProceduresHIGH-VOLTAGE Diode FPC Connector Checkout Procedures Power LevelCheckout Procedures for Relay Problem a Checkout Procedures for Circuit Board Trouble Shooting Circuit board Poor Check the contact of relay 2see Normal Operation Circuit board Fuse Exploded View Control Panel Oven Cavity Latch Board Interior 50FZZA Installation Schematic Diagram of P.C.B Printed Circuit Board May