PSU troubles....

I took a PSU out of a case, a really old case, it had the "Turbo" button... I took all the parts out of it and setup the comp without the case (which we threw away) To my dissapointment i see that it has 4 wires that plugged into the case for power... how do i power this computer WITHOUT using a case OR a switch?

 

Sounds like it's the older AT-style PSU with a remote switch, not an ATX. It has two 5-conductor plugs that connect with the motherboard, right? (The ATX PSU has a single 20-conductor plug (and sometimes an additional 4-wire plug) that connects with the motherboard.)

I think xp 1's answer assumes an ATX PSU, which allows the PSU to be controlled by the operating system. He's given you the case connections to the motherboard. The on-off switch on the front of an ATX case handles only 5 volts and nominal amperage.

The AT PSU isn't that smart. It can be controlled only by a hardware switch. The four-wire cable goes to that power switch. That switch has to be capable of handling the full current load drawn by the power supply from the AC mains, i.e., it should be rated at 250v/15A.

The usual lead colours for the remote switch on an AT-style PSU are:

brown - live from AC mains
blue - neutral from AC mains
This pair is always hot when the PSU is plugged into a live AC mains socket.

black - hot return to PSU
white - neutral return to PSU
This pair is live only when the PSU switch is on.

If there is a fifth conductor (green, or green with a yellow stripe), it's a ground wire and is normally connected to the computer case near the power switch. In the absence of the case, connect it to the PSU case.

The above information was derived from information found in Scott Mueller's "Upgrading and Repairing PCs", 10th ed.

The information above suggests that you could dispense with the switch by connecting the brown and black leads to each other and the blue and white leads to each other -- if you don't mind messing with a PSU that is always on (until you pull the plug from the wall socket).

A disclaimer -- read carefully!: The above information involves some interpretation from the original. I have not tried the connections suggested. You do so at your own risk. Get it wrong, and you'll probably fry the PSU, and maybe more. You're playing with 125 volts and as much current as your wall socket will deliver without tripping the breaker.

 

Interesting.... Im going to try plugging the wires INTO each other, so i dont have to find a switch and then try to wire it lol. Ill just unplug the PSU from the socket after i shutdown the comp!

Also, does that book contain alot of information like that? If so, it seems its time for me to get another book!

 

It should work -- if you connect the right pairs.... (famous last words!)

It's one of my favourite references. Tons of information in over 1600 pages. I picked on the 10th edition (a) because I have it, and (b) because info re older hardware tends to get abbreviated or removed in later editions. "Upgrading and Repairing PCs" is revised almost annually, and is now in its 16th edition. More info at <http://www.quepublishing.com/promotions/promotion.asp?promo=1626&rl=1>. Earlier editions are quite inexpensive on Amazon.

 

It works! now all i need is an old keyboard.... Im talking BEFORE PS/2 times.... Know where i can find one?

 

I see older keyboards (with the 5-pin DIN plug) offered on our local Freecycle group all the time. Find your local Freecycle group here.

Or find a local swapmeet -- probably won't cost you more than maybe $5.

Or spend at least that much on an DIN-PS/2 adapter for a keyboard with a PS/2 plug.