Connecting AT Power Supplies to ATX Motherboards?

Cam Wray asks: "Recently I have upgraded an old AT Server Box, Plenty of Space. It has two power supplies in it. However they are both AT power supplies and the Motherboard is an ATX. What I was wondering is there anyone to convert the AT plugs with an adaptor, or wired etc, to fit an ATX plug. I do not need the Poewer Management side of the ATX as the Computer will be a Backup Server. Any help would be grateful." With AT power supplies on their way out, this information might proove useful for people looking to keep their AT systems up for a little while longer.

Comments

Not easily possible.

[tzanger]

AT and ATX power supplies give you +/-5V and +/-12V. That's where the similarity ends.

ATX power supplies also give a +3.3V an always-on 5V (I think) and have the soft power switch (ground the green wire to toggle on and off). While it's easy to rewire the power switch, that 3.3V is gonna be tricky unless you know what you're doing. We're not talking about throwing on a cheap-ass LM2983 and a couple caps. A 250W ATX supply has a 14A rated 3.3V supply.

Nice idea but not really worth trying.

That's just one thing:

[PD]

You're going to have to also figure out what do do with cutting holes in the box to allow access to the keyboard, serial, and parallel ports. All of these things are different for the ATX board layout.

I just tossed out my AT box and bought an ATX box. Anyone here actually jam an ATX board into an AT box like this guy is doing? What problems did you have?

Re:That's just one thing:

[Medievalist]

PD axed:
Anyone here actually jam an ATX board into an AT box like this guy is doing? What problems did you have?

Yup. Fairly frequently. My main box is a K6-2 these days and it's in an original IBM PC case. Well, OK, the bottom half is from an XT, because I needed the 8 slots at some point (this thing has held at least half a dozen different motherboards at this point, because I prefer metalworking to shopping) but the top half is from an original 5-slot Type A. Still looks like new, nice RF shielding, holds a fairly burly monitor on top.
I have several ATX-modified AT-type systems also, and the worst problem so far was a gashed finger from a raw metal edge I forgot to file off.
I find that you need a goodly supply of standoffs (I use the little brass kind) to adapt pre-AT cases to post-AT boards. And after you chop the case up three or four times with the sawzall, it starts to get, well, sort of floppy. With the top half off, my case has very little structural integrity, because I've had to chop out most of the strengthening members over time to fit variously sized boards, power supplies, and drives. I have pieces of hollow threaded rod from an old lamp mounted across each top corner edge, though, and they hold it together enough to slide the top half on. Once I get the two remaining case screws in it's quite sturdy.
And if anyone looks in my window, they see a total piece of crap computer not worth breaking in to steal. Unfortunately my spouse bought a fancy keyboard, mouse, and monitor, so the camoflage is no longer viable at this point .
--Charlie

Re:That's just one thing:

[kesuki]

Many of the older AT cases were actually built modularly to fit AT or ATX motherboards. If the case is modular then all you need is a power supply a new power button and a backplate. However, the AT power button can be hacked to control an ATX motherboard. ATX power button close the circuit only when depressed, while the AT button actually carries the current that the entire system is using.

Re:How about getting a new case/psu?

[Matador]

Uhhh ... I couldn't agree more.

I think the author of this question needs to question the time vs. money saved.

If one does do the time vs. money, you'll find that if you would of worked doing a "Security Guard" job (many available), at even a mere 7$/hr. One could afford a new power supply and case on just 1-shifts worth of work.

I am sure the author makes more than that, and by the time he asked this question, he could of purchased several already.

Ciao,

Matador

Re:How about getting a new case/psu?

[Nonesuch]

Computer Geeks has several ATX cases under $20. They aren't the world's greatest server cases, but I just bought the one made by Genica and have zero complaints.

Just a satisified customer

How about getting a new case/psu?

[joedumb]

Why not just get a new case and power supply combo for 20$ or a server case for about 150$? Saves the trouble and insures 100% compatibility.

Just buy new ATX power supplies.

[ffsnjb]

I'm comparing an AT and an ATX power supply to each other right now, and they're the exact same dimensions, so you should be able to just buy new ATX power supplies, unless the case you're using doesn't use standard sized power supplies. Other than cutting out the holes for the keyboard, mouse etc., you should be all set. Remember, Dremel is your friend.

Just for reference:
AT Power Supply - Lex Technical Co. LD-200PS
ATX Power Supply - Antec PP-303x (ATX 2.01 compliant)

I know!

[Beowulf_Boy]

DC-Dc power supplys that I have seen just have one model for both.
Basically, they have the same lines, just in different connectors,
Get ahold of some of the connectors, and a little solder knowledge, and your set.