AOC LM725 Service Manual page 35

2.) No Backlight
Check CN102 pin12 =12V
OK
Check ON/OFF signal
OK
Check U201 pin9=12V
OK
Check U201 PIN10,7 have the output of sawtooth wave at short time
OK
Check D201(-), D202(-) have the output of square wave at short time.
OK
Check the resonant wave of pin2 & pin5 for PT201, PT202
OK
Check the output of PT201, PT202
OK
Check connecter & lamp
NG
Check adapter
NG
Check Interface board or main board
NG
Change Q201 or Q202
NG
Change U201
NG
Check Q205, Q206, Q207, Q208, Q203, Q204
NG
Check Q209, Q210, Q211, Q212
NG
Change PT201, PT202
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AOC LM725