System Part - LG CMS9540F Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

2. SYSTEM PART

Power on.
"HELLO"
Display on FLD
OK?
YES
Volume LED
(LD3V31~LD3V40
LD3V42~LD3V49)
turn on?
YES
When turn the volume,
count is change?
YES
FRONT board OK.
CN301
NO
cable connection
OK?
CN301
Pin1, 3, 5
power OK?
CN301
Pin9 ~ 11 data signal
OK?
Q301, 303, 304
grid voltage OK?
NO Q301,Q303,Q304
grid voltage OK?
CN3V01
Pin8, 9 +12 V
OK?
Replace LED.
(LD3V09 ~ LD3V24)
CN3V01
NO
pin31, 32
signal OK?
Check MAIN board.
3-29
NO
YES
NO
YES
NO
YES
NO
NO
YES
NO
YES
NO
YES
Check 17p FFC cable.
Check SMPS board.
Check MAIN board.
Replace DIG301.
Check SMPS board.
Check MAIN board.
Check FFC cable.