VOGONS


First post, by Minutemanqvs

User metadata
Rank Member
Rank
Member

Hello all,

I recently got an ATX to AT PSU converter, which provides 2 loose wires (COM + PS_ON) so one can control the ATX PSU On/Off. Before doing something stupid I would like an advice to double-check if I understand the behaviour correctly. From https://en.wikipedia.org/wiki/PS-ON_Signal and as far as I remember:

220px-ATX_PS_signals.svg.png

- PS_ON is a high signal when the PSU is Off
- If one wants to start the PSU, PS_ON has to be connected to COM

Now this is usually done through the mainboard on an ATX system by pressing the power button for a short period of time. From what I understand, an ATX mainboard uses this signal (or a long press to shut the PSU down) to connect/disconnect PS_ON an COM permanently (and not just a short burst corresponding to the button press).

So going back to my ATX to AT adapter, can I just take a switch to connect these 2 wires together or do I need some kind of additional resistor between them?

Searching a Nexgen Nx586 with FPU, PM me if you have one. I have some Athlon MP systems and cookies.

Reply 3 of 3, by Minutemanqvs

User metadata
Rank Member
Rank
Member

For the records, I measured the current flowing trough these wires without any additional resistor on my PSU: 1.09 mA
So yes, it's safe.

Searching a Nexgen Nx586 with FPU, PM me if you have one. I have some Athlon MP systems and cookies.