LG LSC 27950SB, Service Manual

Page: 79 / 108

2-9. MICOM
TROUBLE DIAGNOSIS
- 79 -
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).
Defective PCB 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 burned 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.)