ATX Power Supply for Bench Use

[GreyOwl]

Have been trying to set up one of my old ATX power supplies to use as a multi-voltage bench unit and have run into a problem. Have run the yellow(+12v) & black(-) to DIMM to measure 12v. Hooked one red(+5v) to a black thru a 10 ohm 10w ceramic resistor for a load. Attached Grey(Sense) to Orange(+3.3v). The green turn on wire is connected to a momentary pushbutton switch then to another black to start. When I push the button all is well but is will not stay powered up. The fan turns and I have 11.85v on the meter but only as long as I hold the pushbutton down. As soon as I release the button the unit shuts back down. Did I miss something somewhere? The power supply came out of one of my older computers and was working when I scrapped the computer

Thanks for any help.
Charles

[x_25]

I find it easier to use an old AT style power supply. The have a built in on off switch and will usually start up even without a load.

[Fedallah]

You have to keep the green PS_ON shorted to ground (black). Just use a non-momentary switch.