Richy85 wrote on 2022-05-03, 11:11:
Because they either have none or are not working.
Oh, really? OK. That's pretty rare with my systems, but well, it happens.
In general, I hate the idea of using ATX units for AT systems as they don't have the definite "mains" power switch any more. It's just nice about the old ones that off really means off.
But, if it can't be helped: Well, look around on ebay which ATX AT adaptors cost the least including shipping if you order ten of them.
Or, since you do have the cables and plugs from the old ones, feel free to cut them off and transplant them to the new units, using solder and shrink tubes - the electrons won't mind, if asked politely.
Then, there's a bloody lot of bollocks going around about PSU requirements.
Some few systems or sound cards will not work without the -5V rail, but rarely, afaik. There are threads for that.
As long as you have one working PSU and the system boots, get some "mains power meter" to plug between outlet and the PSU:
You'll notice that many 90s systems make do with 50 Watts or so under full load like some benchmark. If not yet known, realize that 50 W at 5 V are 10 Ampère.
Meaning any PSU from back then will be able to provide double that on 5 V alone, as virtually all of them have 20 A there.
Consider there's a xx % loss on the PSU itself and then some of that power usage is not 5 V. So as long as that mains wattage divided by five roughly equals the PSU's 5 V rating, you're likely within a safe margin.
By mere amps ratings, almost any shitty old ATX unit will do.
To have some trust in them, AFAIK, Fortron/source (FSP/FSC), Seasonic, Emacs, Enermax and Enlight are brands with some reputation. The modern retail brands like BeQuiet, Corsair, Thermaltake, the lot are usually just those rebranded and repriced. Also, major OEMs like DELL or HP should not be in the habit of installing unreliable garbage, in their own interest, with on-site warranty deals.
In my experience, there are still a lot of AT PSUs to be had, just don't wait for people to know what they are and declare them correctly on line. You'll have to apply bio-optical filtering on ebay - look for grey units, the twin motherboard plugs, a fat black mains switch cable. They usually have the old switch attached or generic plugs that will fit the one on your AT case.
This is already deluxe since it's (ostensibly) from an Acer, 250 Watts, TÜV approved, was not made in China and is only partially covered in rust:
With AT ones, a temp controlled fan is a good sign, as those were rare.
If you get a first PSU and then stick to fixing the first system, chances are you'll find the second by the time you're done. 😉
Of course, any PSU you get, dry test it, give it something to do like a bunch of HDDs you don't care about or halogen lamps or whatever, test the voltages and that they don't go up in smoke.
One hint, some older systems will get by with a pico PSU plus adapter, which may be cheaper and fanless.
Other than that and apart from genuine AT units, if you pay more than ten quid for basic needs, you're being cheated by yourself or someone else:
Have fun and post some nice pictures!