[SOLVED]820-2850 Liquid damage near U9701 and U7201

[phuketmymac]

Hi,

I have that board with an important liquid damage near U9701 and a slight one near U7201.
The board has quarter fan spin.
When the charger is plugged, PPBUS_G3H will come and then drop.

I've checked the current sensing resistors which measure fine.
I did reflow both areas and replaced U7201. Same issue.

I've replaced the ISL6259, but same issue.

Looking for a short on the rails, I believe I have one on PP1V5_S3RS0 (0.04 on diode mode).
When I remove Q7801, PPBUS_G3H will stay on.

There are a few parts on this rail and the CPU, of course...
I will try to remove all the caps and chips on this rail and hope for the best.

What do you guys think?

 

[dukefawks]

What is resistance in Ohm on this rail? 0.04 in diode mode seems really low

 

[phuketmymac]

It is only 44ohms.

 

[dukefawks]

44 ohm is not a problem on that rail. Is PP3V3_S5 and PP5V_S3 coming high?

 

[phuketmymac]

Nope cause PPBUS_G3H is dropping completely. It will remain only if I remove Q7801

 

[dukefawks]

What does it do when a charged battery is connected?

 

[phuketmymac]

Thanks Duke! You're the king.
It was C3618. I could hear a transistor ticking once I plug the battery which was Q7810. Put some alcohol on the area and saw both the cap and the transistor were getting hot.
Removed the cap and good to go.

Easy to get dawn a rabbit hole though... I got tricked by this Q7801