Convert PC Power Supply to Bench Supply

Thread Starter


Joined Dec 25, 2006
I decided to do this project to have one for myself. $8 'ATX' supply to use for a bench supply around the house. Not bad.

The bad news...I am not sure if this thing is an actual ATX power supply. The pin out and wire colors are not the standard that I have read on numerous websites.

Just to name a few. Red is +5V, Black is ground, Orange is 3.3V so on and so forth.

But the power supply my buddy gave me is so far off this industry standard and I have no luck finding a pin out. So I had to open the supply. Thankfully, the PCB board lists the voltages next to the wires:

Red +5V
Black Ground
White -18V
Orange +12V
Yellow -12V
Purple -5V
Grey Power Good

And there are two brown wires that I have no idea what they are. The PCB shows P/C and F/C on the board connections. Any ideas?

Thread Starter


Joined Dec 25, 2006

After a few short trials and errors, I used a 16 ohm, 10W power resistor between the +5V rail, and P/C. Must be 'power control.' All the rails come up. It looks like the +5V rail that always came up is standby power.

Works like a charm.

John Luciani

Joined Apr 3, 2007
The ATX power supply specifications are at

There are usually minimum load requirements for some of the outputs
(typically the high current outputs).

Some of the newer supplies have a PSON# signal that needs to be held low
to turn on the supply. PSON# is usually controlled by circuitry on the motherboard.
Use the +5VSB to power any circuitry you need to have on all the time.

(* jcl *)