View Single Post
Old 03-03-2009, 11:12 AM   #9 (permalink)
home of the odd vehicles
rmay635703's Avatar
Join Date: Jun 2008
Location: Somewhere in WI
Posts: 3,533

Silver - '10 Chevy Cobalt XFE
Thanks: 403
Thanked 753 Times in 564 Posts
Originally Posted by hummingbird View Post
A certain minimum load on the main feedback output is always required for any SMPS to give a stable output

Generally +5V is the main winding and 10 ohm 10W would be good ratings for the power resistor.

You would need the pins 14 and 15 on the ATX connector shorted to bring up the power supply
He has an AT power supply which gets hard wired on through an old contact switch, your comment on load resistor is accurate though.

I suspect that his paticular AT PSU required a load to operate, he attempted to fire with insufficient load and blew out the primary so now its non functional. (not all AT power supplies will survive being powered on without a decent load)

Can the OP try the PSU on a mobo to see if anything happens? My guess is the PSU gave up the ghost.

Anyway I have used old AT supplies for everything from battery chargers to lab power, it should not be real complex, you just need to take care that you always have sufficient load, also what MODEL and TYPE of AT PSU do you have? Are you positive it was functional before you tried using it?

Take a pic, maybe it is not truly an AT but a proprietary unit from a compaq, packard bell or the like.

Good Luck

Pin Signal
1 Power Good
2 +5V or N.C.
3 +12V
4 -12V
5 Ground
6 Ground

Pin Signal
1 Ground
2 Ground
3 -5V
4 +5V
5 +5V
6 +5V

Last edited by rmay635703; 03-04-2009 at 03:28 PM.. Reason: added pinout
  Reply With Quote