HP L1740 Service Manual page 31

17" LCD Color Monitor
2. W/LED No Backlight
Check C820 (+)/C840 (+) =12V
Check ON/OFF signal
Check U811 pin1=5V ?
Check the pin1 of U811 have saw tooth wave
Check D833、D853 has the output of square wave at short time.
Check the resonant wave of pin2 & pin5 for PT801/PT802
Check the output of PT801/PT802
Check connecter & lamp
NG
OK
NG
OK
OK
NG
OK
NG
OK
NG
OK
NG
OK
Check C820/C840
Check Interface board
NG
Change Q821 or Q841
Change U811
CheckQ821/Q841
Check Q821/Q841/D833/D853
Change PT801/PT802
31
HP L1740