IBM L150 Service Manual page 37

2.) W / LED , No Backlight
Check C201(+) =12V
Check ON/OFF signal
Check U201 pin9=12V
Check the pin1 of U201 have sawtooth wave
Check D201(-) have the output of square wave at short time.
Check the resonant wave of pin2 & pin5 for PT201
Check the output of PT201
Check connecter & lamp
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
Change F902 Check
D201/Q209/Q210
Check Interface board
Change Q201 or Q202
Change U201
Check
Q205/Q207/Q203/D201
Check Q209/Q210/C213
Change PT201
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IBM 15" Service Manual