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Trouble Sh ooting
A L502
13. Checking inverter board circuit
Check Vin pin is around 15.5V.
On/off pin is over 2V.
Brightness pin is between 0V and 3.7V.
OK
NG
Check pin 5 of I102 is 5V.
OK
NG
Check CN102, CN103 is connected
right.
It is not inverter problem.
Check Q101, D101, D104 and repair
them.
OK
NG
Check pin 3 of I102 is over 2V.
Check CCFL and repair them.
OK
NG
Check pin 18 of I102 is triangle
pulse.
Check Q106, D110 and repair them.
Check pin 4 of I102 there is soft start
edge up to 4V and pin 11, 12, 19, 20
there is some pulse output.
Check C115, R108, I102 and repair
them.
Check pin 2 of I102 there is up to 2V
from output detection.
Repair I102.
Check full-bridge (I101, I103, D102,
D103, C123, C125) work right.
Check Q102, Q103, CR101, CR103
and repair them.
Repair them.
Check transformer (T101, T102)
work right.
OK
NG
OK
NG
NG
OK
OK
NG
Check detection (C124, C118, C126,
CR102 and like those) work right
and repair them.
OK
NG
Repair them.
