Lenovo G560 power up 3sec

[gcomputers]

hi im working with this lenovo G560 ith
intel core i3 , Hm55 igp
this machine come with scratched screen , power for 3sec and shoot down .

-on PSU not consume current only 020ma .

-flashed bios ec and main , on main chip dont have voltage ec yes.
i see on schematic (as i know) the power of MAIN chip come from HM55 so i
replaced HM55 with another used.

-replaced cpu same problem not consume current only 020ma and shootdown after 3sec no fan activity only i see led of power for 3sec?

ANY IDEA? maybe VCcore ? or IO chip ?
what i need to troubleshot ?

here schematic
https://www.badcaps.net/forum/showth...light=la-5752p

[gcomputers]

Re: Lenovo G560 power up 3sec

any suggestion?

[boyebaran]

Re: Lenovo G560 power up 3sec

hi
+3vs make by +3valw(U4 page 39)
first check +3valw is ok.also +5valw

[gcomputers]

Re: Lenovo G560 power up 3sec

hi
+3vs make by +3valw(U4 page 39)
first check +3valw is ok.also +5valw

Thanks for your reply .
3Valw and 5Valw is present BUT +3VS is 0V and shorted with Ground.
U4 is mosfet Nchannel and is OK.

Any idea where is created +3VS or is created from HM55?

[boyebaran]

Re: Lenovo G560 power up 3sec

you must separate all line connected to +3vs to finding damage part .
one way you can apply external 3v to this line(+3vs).so you can see which part gone to hot-be careful -some times one smd cap is short to GND . it is your own risk.
first remove Q6 and check shorting to gnd
after remove Q6 if shorting solved so you must check C134,135 and Q6
if not solved inform me please
tnx

[arka444]

Re: Lenovo G560 power up 3sec

Guys Check PU7, In this board, most of the time the lower pins of the ISL gets corroded. PU7 Generates 1.1v through PL8