LG Electronics GR-P257/L257 Micom, Trouble Diagnosis, Problems, Symptom, Causes, Checks, Measures

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2-9. Micom

Problems	Symptom	Causes		Checks	Measures	Remarks
Bad PCB	All display	Bad connection	Bad connector	Visual check on connector	Reconnect
electric power.	LCD are off.	between Main PCB	connection from main	connection.	connector.
		and display circuit.	PCB to display PCB.
		Defective PCB trans.	PCB Trans winding is	Check resistance of PCB Trans	Replace PCB Trans	Applicable to
			cut.	input and output terminals with	or PCB.	model without
			PCB Trans temperature	a tester. (If resistance is infinity,		dispenser.
			fuse is burnt out.	trans winding is cut).
		DefectivePCB electric	Defective regulator IC	Check voltage at input/output	Replace regulator.	Refer to electric
		circuit parts.	(7812, 7805).	terminals.		circuit in circuit
						explanation.
			PCB electric terminal	Check fuse in PCB electric	Replace PCB fuse.
			fuse is burnt out.	terminal with a tester.
			STR Parts are	Check if STR No. 2 and 3 pins	Replace parts.	Applicable to
			damaged.	are cut when power is off.		model with
						dispenser.
	Abnormal	Bad connection	Lead Wire connecting	Check Lead Wire terminals	Reconnect Lead
	display LCD	between Main PCB	main PCB and display	connecting Main PCB and	Wire and directly
	operation	and display circuit.	PCB is cut or connector	display PCB with a tester.	connect defective
			terminal connection is		contact terminal to
			bad.		Lead Wire.
		Defective LCD.	Defective LCD.	Check if all LCD are on when	Replace display	Refer to display
				Main PCB Test switch is	PCB.	circuit in circuit
				pressed (or when both freezer		explanation.
				key and power freezer key are
				pressed at the same time for
				more than one second.)

TROUBLE DIAGNOSIS