Looks to me like that diagram is indicating you should switch the AC in.

keenmaster486 wrote on 2025-03-08, 18:55:

Looks to me like that diagram is indicating you should switch the AC in.

The diagram shows a typical DPST switch. The one all the other AT PSUs I've seen have. They are usually fixed to the front of the case.

The switch on the back is a simple SPST switch. One cable is permanently wired to the PSU board.
This is the first time I've ever seen an AT PSU with an SPST switch on the back.

I guess they used an ATX PSU case to cut costs. I think it's a terrible decision.

Has anyone ever seen one of these?

The label it's stuck on with tape, and behind it there's another label.
I'd say someone must've fitted an AT pcb in a ATX enclosure.

Swollen caps aside, that PSU looks rather crappy. There's no filtering on the output or on the input, nor provisions for it.
The two diodes on a bracket instead of a 12V rectifier also screams cut corners.

And the Y caps are fake.

Keep the P8-P9 harness and throw the rest in the bin.

andrea wrote on 2025-03-08, 21:21:

The label it's stuck on with tape, and behind it there's another label.
I'd say someone must've fitted an AT pcb in a ATX enclosure.

You have a very good eye!

I had noticed the tape but not the label behind it.

There's in fact an ATX label behind it.

The "Solar Power" label has a lot of adhesive so I think this was done by the manufacturer.

andrea wrote on 2025-03-08, 21:21:

Swollen caps aside, that PSU looks rather crappy. There's no filtering on the output or on the input, nor provisions for it. Th […]
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Swollen caps aside, that PSU looks rather crappy. There's no filtering on the output or on the input, nor provisions for it.
The two diodes on a bracket instead of a 12V rectifier also screams cut corners.

And the Y caps are fake.

Keep the P8-P9 harness and throw the rest in the bin.

Thanks for the details and the suggestion. I'm going to keep it for the cables and parts, keeping in mind their low quality.

tauro wrote on 2025-03-08, 18:48:

The connector is AT, not ATX so... are you supposed to reach behind the computer to turn it off? Is it a weird ATX/AT hibrid?

Some PC/XTs had the switch on the PSU and no reset buton.
- I don’t mean that big red lever, like on an IBM but like this one here.

The Commodore PC-10 has such a PSU with a small black switch on the back, although with a different connector for motherboard.
(PC and AT clones often used AT PSU power connectors for mainboard.)

https://www.commodore-info.com/computer/item/pc10/en/

I had a 286 machine in a pizza-box case that also required you to reach behind the machine to turn it on or off. You needed to reach even further behind the machine to get to the reset button. At least it had one, though.

Those pizza box PCs are fascinating. They make fine terminals and disk-less stations.
The 16-Bit ISA bus on 286 based models is also fine for NE2000 compatible network cards,
so they can run at their full potential (more or less, in comparison to 8-Bit PC bus I mean).
In case of a PC10 and similar, I thought about connecting a wire to a button switch that goes to RESET pin on PC bus..
Grounding it over a resistor should cause a system reset.

tauro wrote on 2025-03-08, 18:48:

The components don't appear to be of good quality (Rulycons galore) and it has swollen caps. […]
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The components don't appear to be of good quality (Rulycons galore) and it has swollen caps.

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Just noticed the EI28 main transformer. Even with new electrolythic capacitors this psu would struggle at 60- 70 watts.

Maybe there's a cover from another PSU. Anyway, the top sticker isn't the original one either (let alone the bottom one on the cover - 450W WTF?!) - it's from PSU with 110-120/220-230V switch, but this one is pure 230V.