LG LRSC26980TT Service Manual - Page 85

Problems, Symptom, Causes, Checks, Measures, Remarks

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Page 85 highlights

TROUBLE DIAGNOSIS - 85 - 19. Micom Problems Symptom Bad PCB All display electric power. LCD are off. Abnormal display LCD operation Causes Checks Measures Remarks Bad connection between Main PCB and display circuit. Bad connector connection from main PCB to display PCB. Visual check on connector connection. Reconnect connector. Defective PCB transformer. PCB transformer winding is cut. PCB transformer temperature fuse is burnt out. Check resistance of PCB transformer input and output terminals with a tester. (If resistance is infinity, trans winding is cut). Replace PCB Applicable to transformer or PCB. model without dispenser. DefectivePCB electric Defective regulator IC circuit parts. (7812, 7805). PCB electric terminal fuse is burnt out. STR Parts are damaged. Check voltage at input/output terminals. Check fuse in PCB electric terminal with a tester. Check if STR No. 2 and 3 pins are cut when power is off. Replace regulator. Replace PCB fuse. Replace parts. Refer to electric circuit in circuit explanation. Applicable to model with dispenser. Bad connection between Main PCB and display circuit. Lead Wire connecting Check Lead Wire terminals main PCB and display connecting Main PCB and PCB is cut or connector display PCB with a tester. terminal connection is bad. Reconnect Lead Wire and directly connect defective contact terminal to Lead Wire. Defective LCD. Defective LCD. Check if all LCD are on when Main PCB Test switch is pressed (or when both freezer key and power freezer key are pressed at the same time for more than one second.) Replace display PCB. Refer to display circuit in circuit explanation.

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19. Micom
TROUBLE DIAGNOSIS
- 85 -
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
PCB transformer
Check resistance of PCB
Replace PCB
Applicable to
transformer.
winding is cut.
transformer input and output
transformer or PCB.
model without
PCB transformer
terminals with a tester.
dispenser.
temperature fuse is
(If resistance is infinity, trans
burnt out.
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.)