Wow man, I appreciate your detailed instructions and help. Now I got full guide how to replace APW8) Can easily send your text to my techs and they will deal with it. Thank you so much.
In my humble experience with these PSUs that Bitmain make, they are quite robust IMO, their PSUs have a lot more quality than the miners themselves, and I think I can say that at least 7-8 times out of 10 it's only a matter of PSU's fan replacement, and since you mentioned "several PSUs" I can only think that quite a good number of them only need a new fan, and those fans go for pretty cheap like $5-10, it's pretty easy to swap the PSU fan, you just need a screwdriver and a working PSU to test with.
I would love to know that the problem is only with fans. That way we can replace them quickly and save money. Thanks for the hint. We will check fans.
Antminer boards tend not to short out the whole supply line, what usually happens is a chip goes bad but since it's one chip in 64/80 it just raises the voltage slightly on the rest of the chips and shuts down the board because the clock and spi signals don't flow through. You can quickly check by disconnecting the boards from the supply and see if it works. If it does check each board's power connections with a meter looking for 0 ohm resistance.
Ok, got it. Thank you, man! I appreciate it.