Turn on ATX PSU without a ATX-motherboard?

I'm currently converting my A4000D to a tower, see this thread http://www.amibay.com/showthread.php?t=14561
Now I could use some help with a "problem" I'm having.

To turn on an ATX PSU you need to put PS_ON (green cable, Pin 14 or 16) to GND all the time and that is what I'm currently doing. But I would like to use the button on the case not the On/Off switch on the back of the PSU.

The problem is that the power button on all new PC-cases only sends out a pulse when it's pressed to the PC-motherboard which then starts the PSU.

What I need is some kind of circuit that grounds PS_ON when the power button is pressed once so the PSU starts and then when I press it again it removes PS_ON from ground and the PSU turns off.

Any ideas? ;)

Can you not change the switch on the case to a 'Latching' switch and write that to the PSU?

You can made simply circut on 74ls74 and one capacitor , i do it for my Atari XE in PC case also and working perfectly.

do what steve says

remember when 286s had a turbo button on them well one of those would do you fine :)

Also Ian Stedman is making some Amiga ATX on-off adaptors, you may ask him for one.

He is "Stedy" on English Amiga Board.

I would really like to use the switch already on the tower as finding a new that fits/matches the tower won't be easy. There's also limited space for the switch as it would hit the DVD if it's to long.

---------- Post added at 22:54 ---------- Previous post was at 22:53 ----------

Quote:

---

Originally Posted by zaxon

You can made simply circut on 74ls74 and one capacitor , i do it for my Atari XE in PC case also and working perfectly.

---

That sounds interesting. ;)
Could you explain more, perhaps with a picture/drawing on how to connect it?

OK, it's clearly been a while, I thought you just pulsed the two wires on the ATX power supply to turn it on. (I used to use a paperclip!)

For what it's worth, I solved this problem for my A4000 with an ATX PSU adapter that has the header pins for the power switch on the front of the case. :-) Something similar to this:
http://amigakit.leamancomputing.com/...le+with+Switch

Alternatively, you could change the button on the front of the case for one which latches. You might even be able to modify the one you've got. I seem to recall it's just the removal of a spring.

The ATX PS_ON signal must be shorted to ground through a less than 81Ohm resistor or a TTL latch chip.

Simply pulsing the ATX PS_ON signal do nothing but a kick PSU fan turning on for a few seconds.

simply circut for monostabile switch, for on and off atx power supply


7474 (or 74ls74,74hct74) chip,100 nf capacitor,

legs :
1 not connected,
2 connected to 6
3 power button
4 not connected
5 Green (atx on from ATX power supply)
6 connected to 2
7 GND (black from atx supply)
8 to 15 not connected
16 +5 volt (purple wire from atx supply, 5volt standby)

second wire from power " push button connect to GND), add a 100nF capacitor between leg 7 and 3

I can made pcb board for this but is very simple circut.


Done

Quote:

---

Originally Posted by zaxon

simply circut for monostabile switch, for on and off atx power supply


7474 (or 74ls74,74hct74) chip,100 nf capacitor,

legs :
1 not connected,
2 connected to 6
3 power button
4 not connected
5 Green (atx on from ATX power supply)
6 connected to 2
7 GND (black from atx supply)
8 to 15 not connected
16 +5 volt (purple wire from atx supply, 5volt standby)

second wire from power " push button connect to GND), add a 100nF capacitor between leg 7 and 3

I can made pcb board for this but is very simple circut.


Done

---

Thanks!!!
I'll give this one a try. :cool: