Buffalo BU1715 Service Manual page 42

2.) W / LED, No Backlight
Check U201 pin9=12V voltage of C905(+)
Check the pin1 of U201 have saw tooth wave
Check D201 (-), D202 (-) has the output of square wave at short time.
Check the resonant wave of pin2 & pin5 for PT201/PT202
Check the output of PT201/PT202
Check connecter & lamp
Check C201 (+) =12V
OK
Check ON/OFF signal
OK
OK
OK
OK
OK
OK
NG
Check D201/Q209/Q210
NG
Check Interface board
NG
Change Q201 or Q202
NG
Change U201
NG
Check Q205/Q207/Q203/D201
or Q206/Q208/Q204/D202
NG
Check Q209/Q210/C213 or
Q211/Q212/C214
NG
Change PT201 or PT202
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Buffalo BU1715