386SX wrote:

Hi, […]
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Hi,

I have this second at power supply that always ran until now. I tested some motherboard that maybe don't run but I don't know how now the supply when powered don't run the fan and make some strange popping noise like hot oil... I tried on different mobo and same thing and it don't even boot the mobo.
Is it gone in you opinion?
Thank

I would say it is gone and I would disconnect it before smoke

Yeah immediately disconnected... 🙁 ... now let's search another one...

Sounds like one of the filtering caps finally popped. If you love it that much you might be able to fix it by replacing all the caps and checks that the voltage regulators and diodes didn't pop with it.

If the coils in the transformer overheated and unwound/melted it's pretty much gone, but if you check with guys into arcade monitor CRT repair they could teach you how to repair them.

Well I am going to open it and see what it is wrong inside... I update as soon as possible.

Well, it look it's not the power supply the problem!

But the three motherboard I was testing! I've tried in another board and it run ok. So... what it could be? broken traces? capacitors? ...

If the PSU won't even start. Then there is a short circuit on the boards. Check with multimeter the power connector pins against ground to see which line is shorted and then try to find the area. If the boards have tantulum capacitors they are know to make a short when they go bad.

What boards are you talking about? Make some photos 😉

kixs wrote:

If the PSU won't even start. Then there is a short circuit on the boards. Check with multimeter the power connector pins against ground to see which line is shorted and then try to find the area. If the boards have tantulum capacitors they are know to make a short when they go bad.

What boards are you talking about? Make some photos 😉

I can't make photo immediately but the boards are Unichip 386WB 367C and 486A3GX4.
But are you saying checking with the psu on or without?

Without PSU. You check for shorts between power lines and ground. With multimeter you check the continuity or resistance. Search the youtube for video tutorials how to do it.

386SX wrote:

I can't make photo immediately but the boards are Unichip 386WB 367C and 486A3GX4.
But are you saying checking with the psu on or without?

Off topic, but is there any chance that you have documents/manuals for Unichip 386WB 367C ?