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Converting old AT power supply

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WinFlex

Member
Joined
Apr 26, 2002
Location
Boston, MA, USA
Rememer the days when your computer couldn't shut itself off and had a big, heavy manual switch on the front? I am building an external radiator / pump / chiller box for my watercooling setup, and I was considering using the old AT power supply from my ancient P166 to power all the fans and TEC's inside the unit.
So, I took the power supply out, plugged it in, pressed the on switch (if you remember, they are connected with a big long cable that spans through the PC case)... the fan on the supply spun up for a second along with all the fans I had connected to it. Then, it went dead. I repeated and got the same result.
The power supply is far from being overloaded, so this is not why it keeps on shutting off.
One thing that comes to mind is the "Power Good" signal that a power supply sends to the motherboard. Even the old AT supplies have this feature, consisting of an orange wire that sends a +5V DC signal to the motherboard in order to start up the system once the power is smooth and stable. Perhaps I have to connect this power good singal to a ground wire in order to keep the power supply running?
If you have any other ideas, I would greatly appreciate them... Thankx, Felix
 
Could be dead.

I do the same thing your talking about. No MB needed to keep the PSU. Oh, btw you cant do the 7volt trick with AT PSUs.
 
It's not dead...
7 Volt trick... why not? There is a +12V and a +5V rail. Connect them and you get 12V-5V=7V, no matter what!
 
Connect a load to the 5v, without a load, the 5v rail may overvolt and trip the protection circuits.
 
But the Power Good signal is from the PSU and just tells the mobo and cards that the power is, er, good. Shorting to ground wouldn't tell the PSU anything because an AT PSU doesn't read any signals from the computer, and the only signal an ATX PSU reads is the Power On signal.
 
Kool. I will try the load thing and short the 5V rail with a high wattage resistor so that it has some current flowing through it!
 
Try plugging it into a mobo... I have an AT PSU that refuses to work uness plugged into a mobo.
 
well... having a mobo hang aronud my cooling setup will definately be somewhat awkward :) the whole point of this is trying to take the mobo out of the equation :)
 
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