820-00840 brain dead

Narek

Member
I'm working on 820-00840 board which got damaged by coffee spill. It had corrossion around U3700/U3770/U2890/U3900/R5640/U8210 (pictures attached).

I have cleaned it up, replaced U3770 and U2890, repaired broken traces, replaced damaged resistors/caps. Also resoldered U3700 and U8210. Area of U3900 and R5640 looks good after celaning.

- board starts, switch to 20v and takes ~0,45-0,80A.
- CPU gets warm, CPU VCORE is 0,945v constantly, doesn't drop to 0,6v.
- PPBUS_G3H is 13,05v.
- there is no image on internal screen, nor on external monitor with internal screen unplugged
- no USB activity
- trackpad clicks
- no CAPSLOCK light when pressed
- fan is spinning fot ~20s and stops

I have tried clean ME bios from forum and board behaves the same. Dead CPU/PCH?
 

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Last edited:

2informaticos

Administrator
Staff member
There is more damage caused by liquid spill.
Leakage from backlight output (40-50V) to data lines can easy destroy the CPU.
 

Narek

Member
I have inspected LCD flex cable and connector both on motherboard and LCD sides and there are no signs of liquid. I can't see any data lines on corroded are going straight to CPU. Even though it's possible, that CPU died?
 
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