MAX77620A rail shorting to GND


I have an original Switch which suffers from blue screen/won’t boot past the Nintendo logo. It’s an unpatched unit, so a relatively early model.

I have little experience of working on these consoles so am looking for a few pointers/suggestions.

I’ve checked for shorts to GND, and the only location I can find is the area next to the MAX77620A. The resistance is less than 1OHM.

I’ve tried to upload a photo, but I can’t. Its the area to the right of the MAX77620A when you are looking at the IC with the text oriented correctly. Theres 1 inductor and 2 caps.

I’ve removed the inductor and the two caps to isolate the issue. The short doesn’t exist on the side of the MAX77620 - it’s on the side which goes down under the SOC.

I’ve injected 0.8V to try and locate the short using a thermal camera, and its pulling over 1A (current limited), but nothing is getting hot on the camera. I’m not sure of the purpose of this rail so don’t want to increase the voltage until I know what voltage it normally runs at.

My Qs:

  1. I understand the MAX77620 generates the voltage rails for various parts of the system. But what’s this rail that is shorted called? What is its purpose?

  2. What voltage can I safely inject without damaging anything on the rail?

  3. What should I check/remove next to try and isolate the issue further?

Many thanks for any help!

Which of these rails is it you are measuring?

It’s the purple one.


one of three things, either it’s Ram, PMIC or SoC. If the Ram has any indications of a prior reflow/rework then it’s possible somebody has knocked it and possibly merged balls and that would be my first port of call.

Thanks for the suggestions.

I removed the PMIC. Still short.
I removed the RAM. Still short.
I removed the SoC. No short.

Sadly, looks like SoC is dead :frowning:

Just out of interest, do you know what that voltage should be on that rail (purple)? Just for future reference.

Thanks for your help.

purple line voltage I got 1.13v on V1 board, and 1.05v on v2 board

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