LG GR-B197GVQ Service Manual page 88

2-9. Micom
T R O U B L E D I A G N O S I S
- 8 8 -
Problems Symptom Causes Checks Measures Remarks
Bad PCB All
display
Bad connection Bad
connector
Visual check
on
connector
Reconnect
electric power. LEDS
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. (If
resistance
dispenser.
temperature
fuse is burnt out. is infinity, trans 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 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
LED 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 LED Defective LED. Check if all LEDs
are on
when
Replace display
Refer
to display
module. 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.)