Switching on a computer power supply

in article h-adnZ snipped-for-privacy@is.co.za, Mauritz Geyser at snipped-for-privacy@iafrica.com wrote on 3/26/05 9:52 AM:
Switch the power supply on. If you do not know what that means you should not play with electricity.
Bill

If this is an ATX supply (rectangular 20 pin connector in 2 rows) you ground pin 14, usually a green wire. Ground will be any one of the blacks. If this is an advanced AT supply with the 3 pin connector you connect the center ot one of the sides, usually red. It won't hurt to connect to the other one, it just won't start. Some supplies, particularly older AT supplies, won't start without a load. I usually plug in an old disk drive to test them. That is usually enough load to kick them on. Connect the load before you plug it in. Later you can swap it out for a fat 20 ohm (or so) resistor across the 5v.

| in article h-adnZ snipped-for-privacy@is.co.za, Mauritz Geyser at | snipped-for-privacy@iafrica.com wrote on 3/26/05 9:52 AM: | |> Hi Group |> |> I don't know if I'm at the right place but anyway. |> |> I have a old computer power supply (ASTEC Model SA202-3520) that I want to |> use as a power supply for other applications (not for a computer). |> |> What must I do to activate/switch on the power supply on? |> |> Thanks |> |> Mauritz |> |> |> |> | Switch the power supply on. If you do not know what that means you should | not play with electricity.
Newer power supplies have a special wire (or wires) that the motherboard will use to get the power supply to bring up all the voltage lines. Before it is _on_ it is still "on" enough to enable that operation. I think what the OP is asking is what wire, and what signal on that wire. IMHO that is a valid question to ask. Maybe you don't know the answer (I certainly don't) but that's not an excuse for a flippant answer (OK, I'm guilty of having given such answers to people in the past). If you think this is a forum where people should never ask questions they don't already know the answer to, then let me know.
I'm trying to imagine what non-computer project I might do that would get me to use an old computer power supply for it. I can't think of any that couldn't be better done with a wall wart (and I have quite a few of those piled up on a couple shelves).

I assume he is talking about using an ATX powersupply?
has all the details you should need
The violet wire is a constant +5V, which when connected to the green "power on" wire should provide all the other voltages. Whether you wish to do anything with "Power-OK" circuitry or not is another question.
Remember that with switch-modes you will need some load on all voltages, regardless of whether you are intending on using that line.

Wall warts are usually horrendous supplies. The cheapest half wave poorly regulated piece of crap that will work for the vendor. I have tried to use them to trigger SSRs and they have too much ripple at 5ma to latch them on. On the other hand a PC supply is well regulated and will pump out some serious amps on the 5v and 12 rails. Certainly plenty to run a car stereo or for a bench supply. The only problerm when used as a bench supply is they will see a large load change as a fault and shut down.

in article snipped-for-privacy@news2.newsguy.com, snipped-for-privacy@ipal.net at snipped-for-privacy@ipal.net wrote on 3/26/05 12:01 PM:
If that is the case, I apologize.
Bill

If it's standard ATX then green wire to ground is all you need... be aware though that many PC power supplies are of VERY low quality, many will not start up at all without a load (on the right rail, a HD works well), some will blow up...
Tons, PC power supplies, while often pretty nasty on some rails (especially the cheap ones), especially if you're not drawing enough from the regulated rail (usually only one rail is regulated, the others are a derivative of that rail and track it, usually the +5V is the one regulated), are great for alot of amps, especially on the 5V and 3.3V rails, quite a few amps on the 12V rail too... and they are DIRT cheap, often can be had for free...

Others have told how to do this, but you're stuck with the normal +5V and +12V used by the PC.
Here's how to use an old PC supply to give 13.6V/15A.
With a few simple modifications, you can make it supply any voltage from 1-20 volts. You do have to do some electrical mods, but even if you don't feel equal to this, the article is a good place to start.
Be careful! These supplies have capacitors that are charged to >320V. Discharge them or let the supply sit unconnected for a few minutes before you open it. Then be careful of sharp metal edges. :-)

here is a good site, but it's for ATX
anyone know how to do it for an AT one?

| here is a good site, but it's for ATX | | anyone know how to do it for an AT one? | | Is that site run by the Amish Mafia?

So I take it that your question wasn't serious ??
-- Regards ..... Rheilly Phoull