AOC LM925 Service Manual page 37

2.) No Backlight
Check CN902 pin2, 4 = 12V
Check ON/OFF signal
Check U201 pin9=12V
Check U201 PIN1 have the output of sawtooth wave at short time
Check D201 (-)/ D202 (-) have the output of square wave at short time.
Check the resonant wave of pin2 & pin5 for PT201/PT202
Check the output of PT201/202
Check connecter & lamp
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
Check adapter or Main Board
Check Main Board
Change Q201 or Q202
Change U201
Check Q203/Q205/Q207/ D201
Check Q204/Q206/Q208/ D202
Check Q209/Q210/C213
Check Q211/Q212/C214
Change PT201/202
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AOC LM925