AT power supply hack?

Hi all!
I fought for like, and hour and a half today trying to get an AT power
supply to turn on and stay on. I thought all you had to do was tie the
"power good" wire to +5V and away you go!
What am I doing wrong? They are older AT's - I tried 5 different ones,
and two different cords, all have built-in switch, no software on-off.
Thanks,
Ian
Reply to
Ian A. Juby
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Somewhere around the time of 08/23/2003 23:15, the world stopped and listened as Ian A. Juby spoke these words of wisdom...:
All AT power supplies have load sensing on the 5V rail and some have it on the 12V rail. If the load is too light, then it will not turn on as these supplies have a minimum load requirement. The powergood signal is sent from the power supply to trigger a reset of the system processor when it comes up.
As for minimum load, you can get a couple of 8? 20W power resistors from Radio Shack and wire them in parallel and connect them between the 5V rail and ground.
Reply to
Daniel Rudy
You might even get away with using a large wattage bulb. Used this in the TV trade on switched psu.
Dave
Reply to
dave Stanton
Somewhere around the time of 08/25/2003 00:30, the world stopped and listened as dave Stanton spoke these words of wisdom...:
I haven't worked on TVs a whole lot, but I have seen that technique used as a method of current limiting.
Reply to
Daniel Rudy
Hmmph!
Well thanks guys, I don't get it. First off, I had thought about the load and threw some load resistors on - but several 8ohms in parrallel??? That's quite the current draw! :-) I came home last night and grabbed one out of my shop, and it fired up with no complaints! Go figure.
Thanks for the input. Ian
"Ian A. Juby" wrote:
> Hi all! > > I fought for like, and hour and a half today trying to get an AT power > supply to turn on and stay on. I thought all you had to do was tie the > "power good" wire to +5V and away you go! > What am I doing wrong? They are older AT's - I tried 5 different ones, > and two different cords, all have built-in switch, no software on-off. > > Thanks, > Ian > >
Reply to
Ian A. Juby

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