Hardware Tracking down a short to ground

[bootaholic]

I've got a switch which had the USBc absolutely destroyed on it. Pin 18 and 6 (VDDIO and VSVR) on M92T36 are shorted to ground which I'm fairly certain should not be the case. The cap above P13USB is also shorted.

I've removed P13USB, M92T36 and BQ.... Without any change to the short to ground on those pins. Also, USBc has been removed. I've also tried removing each of the shorted caps and testing again / checking the caps, no change to the shorts.

The caps around BQ chip were not shorted.

Anyone have suggestions of other things to check?





Sent from my Pixel 4a using Tapatalk

 

[lpoolm]

Made any progress on this?

 

[fa2k]

i would suggest injecting voltage to the cap above P13USB. If you have a lab power supply, i would start with 1V. Something must getting warm, you just have to find it

 

[CHTechRepair]

I've got a switch which had the USBc absolutely destroyed on it. Pin 18 and 6 (VDDIO and VSVR) on M92T36 are shorted to ground which I'm fairly certain should not be the case. The cap above P13USB is also shorted.

I've removed P13USB, M92T36 and BQ.... Without any change to the short to ground on those pins. Also, USBc has been removed. I've also tried removing each of the shorted caps and testing again / checking the caps, no change to the shorts.

The caps around BQ chip were not shorted.

Anyone have suggestions of other things to check?





Sent from my Pixel 4a using Tapatalk

Hi there

So the cap you have a short on is the 3.3v logic or IO power rail. This goes to many many things. (GPU, M92, P13, eMMC) I believe It is created by the big PMIC on the back of the board with all the coils and caps around it (+max). I'm not so good with chip names I steal from donors and reball usually. Injecting 3.3v and using alcohol or a thermal camera to find heat is the easiest way to diagnose your problem. I have bad news. eMMC and GPU are inseparable without modification and GPU is a pain in the ass to replace. GPU likes to short this rail. Having a short here with M92 and P13 off is scary. Good luck.