I don't trust any old ones. I'm running a 2ghz socket A without the 12v connector on a modern power supply. Granted it is a decent Corsair. I've even ran it temporarily on a Corsair 450w SFX power supply.

edit: For context, I have had some nice parts killed by "good" old Antec power supplies.

I plan to recap the few psu I have with -5V, and all my AT psu at some point. It's cheaper the more caps you buy, so doing them all at the same time makes sense to me. And I can clean them all out and replace any faulty fans at the same time.

Those thin tall caps are custom made by request, that's why you usually cannot find them when buying at regular distributors. Years ago I got a batch of tall 3300uF/16V caps through a guy that got them directly from Nippon Chemi-con, which allowed me to refurbish a few really cramped Antec power supplies from the early '00s. Sometimes you can find alternative ways to replace them, for example using caps rated for 6.3V instead of 10V on the 5V and 3.3V lines. As for your solution, I guess it could work, but I would be wary about extending the legs too much from the PCB.

Regarding you main question, it depends: if the power supply is well designed and it's just refurbishing basic component such as caps, the fan or something like that, then sure! However, if there are any burn marks, massive destruction, or custom components like the transformers are blown, then it's not worth it IMO.

Again, I expect the "old power supplies are going to make your computers go up in flames!!!!1!" crowd to pop in. Just remember that what matters the most is how well designed the PSU is, rather than when it was made.

ptr1ck wrote on 2022-04-08, 00:26:

I don't trust any old ones. I'm running a 2ghz socket A without the 12v connector on a modern power supply. Granted it is a decent Corsair. I've even ran it temporarily on a Corsair 450w SFX power supply.

edit: For context, I have had some nice parts killed by "good" old Antec power supplies.

antec were considered good back in the day because the bar back then was so low. most people were using crappy psus that were tossed in free with the case. most of them antec true powers that were considered awesome back then have leaky caps now.

For me it depends.

If the power supply is something weird then yes, I'd repair it. I've got a pair of SPARCstations (an IPC and an IPX), a pair of AlphaStation 200, a Prioris LX, an AlphaServer 1000A and probably a pair of MicroVAX 3500 all with proprietary PSUs awaiting repairs mostly due to bad caps. If its just a random AT power supply then I'd label it with the fault, put it in the box of faulty PSUs and grab another working one. If I some day run out of working ones then I'll probably start repairing them. I have considered being more proactive and replacing caps on working PSUs before they become a problem but component shortages are a problem at the moment. For ATX I'd be tempted to just buy a new one if it will do the job.

I've never had any reason to not trust old power supplies. Never had one fail in an exciting way and I've never seen or heard of a failed PSU causing damage to other components though I'm sure its possible. In my experience they just stop working (the SPARCstations and AlphaStations simply don't turn on anymore) or become unreliable (after a while the Prioris LX starts power-cycling itself and failing to POST, the MicroVAXen were intermittently stopping part way through POST). When it comes to old hardware I find tantalum capacitors a far more likely source of unwanted excitement. When I spot tantalums in something that's not been used in a long time the first power on happens outside.

I did fix old PSUs in the past, but these were from the AT days.
On a few occasions, I basically rebuilt the PSU.

If it's an ATX PSU that's broken, it depends.. If the PC system in question needs voltages/amperes nolonger part of newer ATX revisions.. Yes, maybe.

Same goes for non-standard form factors. Power Macs had modified ATX PSUs with a non-standard pinout.
I fixed them, too: Replacing caps, defective fans..

So it's really hard to answer. It depends on the situation. 🤷‍♂️
General speaking, let's just keep in mind that power supplies are no kids play.
A certain amount of soldering skills are required. If the PSU heats up, bad solder joints can make components drop from PCB etc.
Not good if it's a vital filtering cap that ends up not being connected. Cold solder joints are also bad.

BLockOUT wrote on 2022-04-08, 00:13:

So in order to build a machine from that era you need good Power supply with many amps on the 5v, maybe 40amps or 50amps.
While the ones being sold today.....the amps on the 5v is less than 25.

Eh, this is where urban legends of "ye olde PCs with super strong 5V lines" got us. You realize that 40A at 5V is 200W, right? And that's not even touching the 12V line or auxilary voltages.
The most 5V power hungry systems I remember were Pentium III, and even those would probably run fine with "merely" 25A unless somebody just had to have a bunch of SCSI HDDs spinning all the time. Most if not all P2+ systems would be ATX alredy and using 3V3 for chipset and memory, as well as PCI and CPU bus. So it's only really the CPU core, ISA and drives that would still use 5V and of that it's the CPU VRM that draws most power. Assuming it's running on 5V and not 12V line - just because the mobo doesn't have an extra CPU connector it doesn't mean the 5V line is used for that purpose. Linear regulators were a thing during 486 and Pentium days but later systems used much more efficient switching mode regulators.

Not that it's much different with modern systems - people keep using 1500W PSUs for PCs that would draw 450W if everyhing was cranked to max. Granted, there are some NVidia GPUs that pull such awful current spikes that properly rated PSUs trip or brownout, but that's more to do with piss-poor GPU design and 12V power rail limitations than actual wattage needs.
Or, to put it in different perspective, if you connect a 50A capable PSU to a PC motherboard and something is shorting 5V line (CPU put in wrong, ISA card not sitting properly in the slot, a stray PSU connector touching something) then there's going to be some expensive fireworks. And the PSU will happily set everything on fire and fan the flames.

BLockOUT wrote on 2022-04-08, 00:13:

So would you fix an old power supply? would you replace all caps?

Q1: Yes. Q2: Depends. I would replace the secondary caps if I see too much ripple or any signs of them going bad. Or if the PSU was faulty and I had to repair it, then it's just one extra step. I am talking about AT PSUs though, for ATX I'd probably get a new one. The easier to fix ATX PSUs do not have PFC and are usually cheaply built and not worth the trouble. The ones worth the trouble are usually too difficult to properly fix (like the modern digital ones with gold/platinum ratings).

Deunan wrote on 2022-04-08, 14:12:

Eh, this is where urban legends of "ye olde PCs with super strong 5V lines" got us. You realize that 40A at 5V is 200W, right? A […]
Show full quote

BLockOUT wrote on 2022-04-08, 00:13:

So in order to build a machine from that era you need good Power supply with many amps on the 5v, maybe 40amps or 50amps.
While the ones being sold today.....the amps on the 5v is less than 25.

Eh, this is where urban legends of "ye olde PCs with super strong 5V lines" got us. You realize that 40A at 5V is 200W, right? And that's not even touching the 12V line or auxilary voltages.
The most 5V power hungry systems I remember were Pentium III, and even those would probably run fine with "merely" 25A unless somebody just had to have a bunch of SCSI HDDs spinning all the time. Most if not all P2+ systems would be ATX alredy and using 3V3 for chipset and memory, as well as PCI and CPU bus. So it's only really the CPU core, ISA and drives that would still use 5V and of that it's the CPU VRM that draws most power. Assuming it's running on 5V and not 12V line - just because the mobo doesn't have an extra CPU connector it doesn't mean the 5V line is used for that purpose. Linear regulators were a thing during 486 and Pentium days but later systems used much more efficient switching mode regulators.

Not that it's much different with modern systems - people keep using 1500W PSUs for PCs that would draw 450W if everyhing was cranked to max. Granted, there are some NVidia GPUs that pull such awful current spikes that properly rated PSUs trip or brownout, but that's more to do with piss-poor GPU design and 12V power rail limitations than actual wattage needs.
Or, to put it in different perspective, if you connect a 50A capable PSU to a PC motherboard and something is shorting 5V line (CPU put in wrong, ISA card not sitting properly in the slot, a stray PSU connector touching something) then there's going to be some expensive fireworks. And the PSU will happily set everything on fire and fan the flames.

BLockOUT wrote on 2022-04-08, 00:13:

So would you fix an old power supply? would you replace all caps?

Q1: Yes. Q2: Depends. I would replace the secondary caps if I see too much ripple or any signs of them going bad. Or if the PSU was faulty and I had to repair it, then it's just one extra step. I am talking about AT PSUs though, for ATX I'd probably get a new one. The easier to fix ATX PSUs do not have PFC and are usually cheaply built and not worth the trouble. The ones worth the trouble are usually too difficult to properly fix (like the modern digital ones with gold/platinum ratings).

tl,dr but think he got it. There are TDP figures public for Athlons. I ran an athlon 700 at 900 with a cooler barely above socket 7 back then.
Go look up Ohm's law.

I also got some old PSUs, and i've got two AT P8-P9 PSUs that seem dead, they have been stashed for years, are they worth saving?

Luke4838P wrote on 2022-04-08, 16:57:

I also got some old PSUs, and i've got two AT P8-P9 PSUs that seem dead, they have been stashed for years, are they worth saving?

I'd say if they only need recapping, it's worth it. Good AT psus are not easy to get cheap here

yea during that time we used crappy power supply models in my area.

my first real psu was a topower that had like a mirror finish on the metal. extremely heavy. I always used cheap brand and light psu on pentium2 and 3 i think most were 250W during that era.

debs3759 wrote on 2022-04-08, 17:21:

Luke4838P wrote on 2022-04-08, 16:57:

I also got some old PSUs, and i've got two AT P8-P9 PSUs that seem dead, they have been stashed for years, are they worth saving?

I'd say if they only need recapping, it's worth it. Good AT psus are not easy to get cheap here

Those PSUs date back to 1994-1995 and they were surely working 10 years ago due of me seeing these PCs active and they were stashed working 100%.
I also got an olivetti power supply (m300 30) with the motherboard but no expansion card.

debs3759 wrote on 2022-04-08, 00:41:

I plan to recap the few psu I have with -5V, and all my AT psu at some point. It's cheaper the more caps you buy, so doing them all at the same time makes sense to me. And I can clean them all out and replace any faulty fans at the same time.

I've actually been wondering on and off now for a while where the best spot is to buy new caps?
I know about many not being made anymore for years and the fake ones, but I'd love to get reliable info on getting workable ones for these old boards (and this time this includes PSU PCBs).

At this point, for desktops, I'd attempt to fix them. Same for large scale docks like my Versa Dock (which I'm fixing - hence why the Versas have not been docked in months). AT/XT/Baby AT PSU's are getting harder to get, and most of my machines are AT/XT based machines in older cases.

For laptops, I keep finding new ways to power them with newer power supplies, save for the NECs which for some reason I'm still able to find OEM PSUs for for rather cheap still. But the ones I have never burn out so not much of an issue.

Tetrium wrote on 2022-04-10, 07:50:

debs3759 wrote on 2022-04-08, 00:41:

I plan to recap the few psu I have with -5V, and all my AT psu at some point. It's cheaper the more caps you buy, so doing them all at the same time makes sense to me. And I can clean them all out and replace any faulty fans at the same time.

I've actually been wondering on and off now for a while where the best spot is to buy new caps?
I know about many not being made anymore for years and the fake ones, but I'd love to get reliable info on getting workable ones for these old boards (and this time this includes PSU PCBs).

I'll be getting what I can from Digikey and/or Mouser

debs3759 wrote on 2022-04-10, 16:34:

Tetrium wrote on 2022-04-10, 07:50:

debs3759 wrote on 2022-04-08, 00:41:

I plan to recap the few psu I have with -5V, and all my AT psu at some point. It's cheaper the more caps you buy, so doing them all at the same time makes sense to me. And I can clean them all out and replace any faulty fans at the same time.

I've actually been wondering on and off now for a while where the best spot is to buy new caps?
I know about many not being made anymore for years and the fake ones, but I'd love to get reliable info on getting workable ones for these old boards (and this time this includes PSU PCBs).

I'll be getting what I can from Digikey and/or Mouser

Thanks. Both of these ship to The Netherlands, neat 😜

You can check TME as well (tme.eu) - while their stock/selection isn't as great as Digikey, they might have better prices. For small orders the shipping should be cheaper as well since it's inside EU.

does anyone know if difikey accepts paypal ?
i think mouser does not accept paypal payment.

I have been thinking about recapping both of my voodoo5 because the prices for it are to the moon.
I have seen really bad leak damage on old cd-roms pcbs from 1993 where smd aluminum capacitors were used , and they did a mess on the pcb eating everything.

BLockOUT wrote on 2022-04-14, 03:26:

does anyone know if difikey accepts paypal ?

Their help pages say they accept it.