LG CM9730 Service Manual page 48

ELECTRICAL TROUBLESHOOTING GUIDE
Power on.
"HELLO"
Display on FLD
OK?
YES
Volume LED
(LD3V31 ~ LD3V49) Jog LED
(LD3J31 ~ LD3J49)
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, 10, 11 data signal
OK?
Q301, 303, 304
grid voltage OK?
CN3V01
NO
Pin8, 9 CN3J01 Pin10,11
+12 V OK?
Check
CN3V01 Pin5, 6
CN3J01 Pin15,16
I2C data OK?
Replace LED.
(LD3V31 ~ LD3V49)
(LD3J31 ~ LD3J49)
CN3V01
NO
Pin12, 13 signal
OK?
Check MAIN board.
3-31
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.