LG CM8440 Series - System Part

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