Whatspower P221C Repair

[BlackRasberry]

I have a few P221C power supplies I am trying to fix. After cracking them open, I dont see any visual problems with the power supply components themselves. I plug it in and there is no voltage. Fuse is good, some have replaced the NTC 16D-20 thermistor fuse and have had success, but both of mine have continuity. After removing some heatsinks, the components underneath them were NCS P40115AGU and all of them looked good. Any suggestions?

[BitMaxz]

How about the PSU fan on the back is it running?

Try to check diodes on the back of the PSU board there might be some shorted diodes also check the big capacitors if you have a digital multimeter that can read the capacitors then try to check those big capacitors and make sure the capacitance value under that wrapper is the same if not you need to replace them and make sure before you test short them using Driver Screw and don't forget to unplug them from the outlet before you test them.

[BlackRasberry]

I checked each diode and they all read 1.3v one way and 0.59v the other. All 3 of the largest 470uF capacitors read 1.3mF (3x470uF). Is this because they are still connected to the circuit?

I also tested all of the mosfet voltage regulators on the AC side and with a continuity test, they seemed ok.

I wish there was more information online about this power supply, maybe a drawing of the circuit?

[NotFuzzyWarm]

Um, when testing diodes and caps you need to remove one end of them from the circuits to fully verify what you see. In the  case of diodes they MUST conduct only in 1 direction and you reported conduction in both. Hopefully just from them still being connected. In the case of caps you are probably good and they are not shorted - at least not at the low voltage the meter provides. If the static tests look good then measure the actual voltage across the caps to be sure they hold up to full voltage.

[mikeywith]

I wish there was more information online about this power supply, maybe a drawing of the circuit?

Chances are, there is nothing publicly available, but to be honest with you, Whatsminer community here is pretty small, I think only a few of us own those gears, I do but sadly I have little to no experience in fixing these PSUs, I would suggest that you visit the Whatsminer community on telegram https://t.me/whatsminercommunity

Search the chat history, a lot of the content is in Russian so you might need to translate some messages that mentioned the PSU model in Latin alphabets, but if you can't find any, just ask and hopefully, someone will give you an answer.