1914 Controller Problem - MCU short to ground

[CptChronic]

Hello guys,

I have a problem with a Xbox Series Controller (1914).
It won't turn on with batteries, if I use a USB there is a high pitched whine coming from somewhere, it's hard to pinpoint but I'm guessing the ARM chip.

I've tested alot of it with my DMM and compared to a working board, I am getting a short to ground on many of the caps, where I do not on the working board, I've put a red dot on the ones shorted to ground.


My image isn't showing for some reason but you can see it here: https://imgur.com/a/eC5TTF0

Has anyone come across this before? Any ideas?

The button board is fine, it works with a new MCU board.

Thanks

[CptChronic]

All sorted, there was one faulty capacitor C307. Replaced and now it turns on 

[bakachelera]

How did you know it was that specific cap? teach me your technique please. Nice work

[RDC]

You can inject a current limited 3v on the 3.3v rail and use a thermal camera to see what heats up first.

The cheaper, but still every bit as effective way, is to use a few drops of rubbing alcohol on the board and then when you inject the voltage it will evaporate much faster off of the component that heats up first, and is thus most likely where the issue is.

[bakachelera]

Thanks RDC! And here I was removing cap by cap in this Series controller with no LT RT input lmao. I turned out lucky as it was C33 which was on short. causing C37 to also short lmao.

[RDC]

Welcome. A lot of the capacitors in there are in parallel, and if one is shorted then every other cap that is in parallel with it will just measure shorted, even though they aren't.

[CptChronic]

You can inject a current limited 3v on the 3.3v rail and use a thermal camera to see what heats up first.

The cheaper, but still every bit as effective way, is to use a few drops of rubbing alcohol on the board and then when you inject the voltage it will evaporate much faster off of the component that heats up first, and is thus most likely where the issue is.

I'm too poor for a thermal camera so the alcohol trick is what I used. Its a very handy trick to know 

When injecting the voltage my bench power supply won't work due to the short so I solder a couple of wires onto the 3.3v and ground pins on J5 and attach them to 2 AA batteries (not soldered so they can be quickly removed) that are housed in the battery compartment of the rear shell