i have hp compaq 6730b i plug charger there's no power .
i mesure voltage on dc jack i find on jack1 ( 1,2) 19.9 v on (3) 6.5v and the others all mass
on mosfet q510 ther's voltage on source (1,2,3) 19.9 v on gate (4) 18.9 v but no voltage on drain( (5,6,7,8) ov
i change mosfet twice but the probleme still the same.
any help please
thanx

Sorry, I not read your post carefully

Check
ADP_EN# must be low
PWR_GOOD_3 must be high

thank you for anwer
the voltage on U501 pin 7 for LM_393DR2G is 17.7v
there's no voltage on U510 LM_393DR2G (pin1=0v, pin2=0v,pin3=0v,pin4=0v,pin5=0v,pin6=0,pin7=0v and pin8=0v)
PWR_GOOD3 = 0v
ADP_EN = 17.7 v

im waiting for your help please

hi sir
problem is resolved i have change U36 (TPS51120) and the pc is again alive
thank you for your help