Do you have a multimeter?

Post HQ pics of your board and specifically the power circuit.

Nexxen wrote on 2024-07-15, 18:20:

Do you have a multimeter?

Yes.

Are the two mosfets producing the correct voltages? 3.3 and 2.8v?

CS5165 https://pdf1.alldatasheet.com/datasheet-pdf/v … RRY/CS5165.html
Does is work accordingly?

Vcc2 and Vcc3 are correct with voltages?

Nexxen wrote on 2024-07-15, 20:34:

Are the two mosfets producing the correct voltages? 3.3 and 2.8v?

Nothing produces any voltages as the PSU doesn't power up at all.

ux-3 wrote on 2024-07-15, 20:38:

Nexxen wrote on 2024-07-15, 20:34:

Are the two mosfets producing the correct voltages? 3.3 and 2.8v?

Nothing produces any voltages as the PSU doesn't power up at all.

Got distracted.
If you test them for a short? 0 ohm or any resistance?
The CS?

If you have a hot air station you could desolder one and check for the short.
Caps are 0 ohm?
Are chipset's legs touching?

This is the realm of boring chores, a lot of foot work probing stuff like you have no life to live.
Next move is to desolder a mosfet and check, then caps...

Before all you could clean the board (soap) and look for broken parts, traces, anything like that.

Go back to basics first. Check that there are no dead shorts between any of the voltage rails and ground.

I have no hot air station.

The board quit starting from now to 5 minutes later, build in a case.

I guess it "expired".

ux-3 wrote on 2024-07-15, 21:46:

I have no hot air station.

The board quit starting from now to 5 minuted later, build in a case.

I guess it "expired".

It's gonna take some time and patience but I'm sure it's a cap or the two mosfets (power circuit).

Maybe make it a side project and do something from time to time.
Come on, you want to call it so soon??? Let's give it a chance 😀

how can I check the mosfets?

I dont get why people are jumping at CPU vrm first.

Basics are:
- find ATX pinout, with unplugged supply measure resistance between ground and +12V +5V +5V_StandBy rails
- with ATX supply connected measure voltage on PS-ON pin while trying to push power button
- with ATX supply connected measure voltage on Power button pins of the motherboard

ps: its a mobo for one of those bottom of the barrel ~2000 "value" systems https://theretroweb.com/motherboards/s/bcm-in530

I got a different replacement S7 board. After it worked fine for a day in all sorts of tests, after a week of vacation, it suddenly had difficulty to power off and then would not power on at all. It worked again, then acted dead once more. Sounds familiar?
So I changed the PSU. I noted my workbench power button cable had a side broken. Replaced that. Then it powered on reliably again. Then I thought: I only used a different PSU briefly with that broken button. Then I went back to the original PSU. Which caused the same trouble again, after working fine for some time. Perhaps...
And yes, with a different PSU, my old beloved SS7 board powers up again. 😀

So I have a faulty PSU to diagnose. It doesn't start up every once in a while... Good trade!

ux-3 wrote on 2024-07-27, 19:05:

I got a different replacement S7 board. After it worked fine for a day in all sorts of tests, after a week of vacation, it sudde […]
Show full quote

I got a different replacement S7 board. After it worked fine for a day in all sorts of tests, after a week of vacation, it suddenly had difficulty to power off and then would not power on at all. It worked again, then acted dead once more. Sounds familiar?
So I changed the PSU. I noted by workbench power button cable had a side broken. Replaced that. Then it powered on reliably again. Then I thought: I only used a different PSU briefly with that broken button. Then I went back to the original PSU. Which caused the same troube again, after working fine for some time. Perhaps...
And yes, with a different PSU, my old beloved SS7 board powers up again. 😀

So I have a faulty PSU to diagnose. It doesn't start up every once in a while... Good trade!

🤣
I was already in the power circuit fault and it was the PSU! It was power, even if not the board's ... 😀
Happy it wasn't faulty to begin with. Have fun with it!!

rasz_pl wrote on 2024-07-16, 00:47:

I dont get why people are jumping at CPU vrm first. […]
Show full quote

I dont get why people are jumping at CPU vrm first.

Basics are:
- find ATX pinout, with unplugged supply measure resistance between ground and +12V +5V +5V_StandBy rails
- with ATX supply connected measure voltage on PS-ON pin while trying to push power button
- with ATX supply connected measure voltage on Power button pins of the motherboard

ps: its a mobo for one of those bottom of the barrel ~2000 "value" systems https://theretroweb.com/motherboards/s/bcm-in530

I had many in a short time span and saw VRM everywhere.
Even for your lawnmower! 🤣