Thread: Power Good @ Mk2.5

Originally Posted by Firebird

Hi!

Up to now, I used an old PIII with Mk2.5. Everything worked fine. But now i bought a new VIA Mainboard, and the PC doesn't start. Fans are running, voltage is OK, but it doesn't boot up. I tried it without HDD, and the Mainboard is also OK.
I've read, that maybe the problem is the "power good" signal, but my Mk2.5 doesn't have such signal.
Now my Question: How can i build the "power good" signal? What should I connect?

Please help me ...

Thanks, Bernhard

The ATX PowerGood signal (gray wire) is a +3.3V inpupt to the PC (+5V tolerant) and is high after all three supplies come up. You can fool a PC into turning on by tying this line to +3.3V (orange wires). The problem with doing this is that it will stay high for too long when the PC is told to turn off and it will hate you when you try to turn it back on. You should be able to cycle the power and get it to come on again though. I wouldn't recommend this as a permanent fix but you can try it to see if the power good signal is the problem.

Oh thanks very much!
I'll try it.
If it works:
Is there a circuit in the net, that manage the "Power Good" signal right?

Thanks

Originally Posted by Firebird

Oh thanks very much!
I'll try it.
If it works:
Is there a circuit in the net, that manage the "Power Good" signal right?

Thanks

Due to timing considerations, it is not a simple fix. It would be cheaper to replace your power supply than to try to add a circuit with this feature.

Hi!

OK, there was a mistake.
My PowerGood Signal was connected tu +5.
But when i connect it to +3, the result is the same, fans and HDD are running, but the PC doesn't boot up.
The only ATX cable that is not connected, that is the green one.

What else can i try?

The Mainboard works with every normal Power supply, and the Mk2.5 works fine with the old PIII Mainboard.

Thanks ...