motherboard NM-A751 (Lenovo ideaPad 310)

[Shummi]

Hi
I Am new to Laptop repair, but not to elecronics
Model ?? motherboard NM-A751
Look like the schmatic from here works
https://www.badcaps.net/forum/attach...7&d=1589197578

I found the laptop as scrap, but complete without HD
The bare motherboard is stripped, and sometimes draw 100 mA,
then 3VLP and 5VALW is OK
Theres no +3VALW and PU401 get really hot, no change if i press ON/OFF
if i desolder PJ402 it comes up.
After soldering PJ402 again,
I have tried to desolder PJ502, PJ 508, JL1 and J7
But no +3VALW
I have tried external 3V, with 4A current limiter i rise to 1V, theres not that gets hot, the CPU gest a little warm (wish i had a thermocamera)

I am stuck, as theres no print layout in the schmatics.
I wonder if it is a shortet cap.

Any help will be apriciated
/Jesper

[mon2]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

Boardview is attached.

[Shummi]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

Hi
Thank you for the quick reply
Unfortenately, i can't open it with the viewers i found

/J

[mon2]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

Sorry. I knew I forgot something...the boardview file is encrypted. You will need to download and expand a different version of the tool to read this file.

1) Download the special viewer from here:

https://wetransfer.com/downloads/d5e...4153900/b99fc3

2) Expand this download to a local folder.

3) Launch the BoardViewer.exe program from this folder. Then load the above encrypted boardviewer file to view.

4) To use the tool to view normal (no encryption) boardview files, launch the Boardviewer_normal file instead.

[Shummi]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

Hi
That helped

Any tips to proceed ?
Should i choose +3VALQW in nets selection, and just disconnect one after one?
From the schmatic it dosnt seem possible to diconnect the CPU?

/J

[piernov]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

If PCH gets warm when injecting on 3V rail it's dead.

[Shummi]

Re: motherboard NM-A751 (Lenovo ideaPad 310)

OK, that wasn't fun as a first time laptop repair.
Thanks for all the help anyway.
BR Jesper