Hi everyone,
I'm trying to learn how to repair ASICs and as I have a few S9 boards that don't work I thought they would be good for practice.

I have a repair guide from antminer that I have downloaded but to be honest most of it is over my head and the board shown is a different version to mine.
I'm picking bits up here and there online but as most guides seem to dive into finding a faulty chip but as the first board I have here hardly has any voltage at the domains, I feel I need to take a step back and understand how the power circuits work.

I have V4.21M boards

I definitely have 12v coming into the board but very low voltage at the domains, I believe less than 0.1v

I'm convinced I should be starting at the DC-DC circuit but I'm struggling to figure out where to test for the voltage and then how to test each component.


If anyone could point me in the correct direction it would be much appreciated.
Thanks