Dell E156FPc Service Manual page 44

No Backlight
Check C201 (+) =12V
Check ON/OFF signal
Check IC201 pin9=12V ?
Check the pin1 of IC201 have saw tooth wave
Check D201 (-) have the output of square wave at short time.
Check the resonant wave of pin1 & pin6 for PT201
Check the output of PT201
Check connecter & lamp
NG
OK
NG
OK
NG
OK
NG
OK
OK NG
NG
OK
NG
OK
Check F902
Check Interface board
Change Q201 or Q202
Change IC201
Check Q203/Q204/Q205/D201
Check Q206/Q207/C221
Change PT201
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Dell E156FPc