Sony Vaio VGN-N31M - No Post/Half Dead

[JaYmEz]

Hello friends,

Motherboard: MBX-160 Rev. 1.0

I press the button and the green light turns on but nothing happens and it stays like that forever. If i press the button for 10s or more it doesn't turn off, i need to unplug to turn it off.
When it's on i can hear a low whistle but i didn't found the source.

When visual inspecting the board i found the PQ21 (IRF7904PBF) completly burned out and replaced it but no change on the problem.

I've been using this schematic:
https://www.dropbox.com/s/7yzu04kx1m...1_sch.pdf?dl=0

If anyone has an idea where to look...

Thank you =)

[JaYmEz]

Re: Sony Vaio VGN-N31M - No Post/Half Dead

Hello again,

I've attached some photos of the board and the schematic.
I've found that the PU7 was getting very hot when i turn on the board. I attached photos of the PU7 and PQ21 zones.

Here are the measures i made with the board ON:
PQ21 pins:
1- 0,11v
2- GND
3- GND
4- 0,015v
5- 0,09v
6- 0,09v
7- 0,09v
8- 19,6v

PU7 pins: (this one is hot with board ON)
1- 3,26v (IN)
2- GND
3- 3,3v (SHDN)
4- 0,86v (SET)
5- 0,18v (OUT)

If anyone has an idea what could be the problem.
Thank you! =)