ATX power supply in an A4000

[Rigger]

Since no one was interested in buy/trading my A4000 the upgrade bug has hit me again. Currently I use 2 power supplies for a total of 385 watts. I'd like to replace this with just a single 450 - 500 watt ATX power supply.

The A4000 pin-outs are;

1 - Orange (+12v)
2 - Red (-12v)
3 - Brown (Power Good)
4 - Yellow (+5V)
5 - Blue (Ground)
6 - Blue (Ground)
 
"Power Good" is a TTL output from the power supply, a logical high indicating a stable power supply.


ATX Power pin-out shows the pin-outs for the ATX power supply. Which pi-out on the ATX power supply would satisfy the "Power Good" requirement of the A4000 power supply?

[A4000Bear]

It has been quite some time since I did an ATX power supply hack, but if I remember rightly, Pin 8 (grey) is the equivalent of the A4000 "Power good" signal. Just connect it straight up.

You will also need to pull pin 14 (green) to ground with a switch. The idea is that the ATX power supply is actually powered up at all times, and this switch actually beomes the power switch that turns on the Amiga.

Just be careful to bear this in mind when working on your A4000 - I fried a power supply in a PC once when I disconnected a hard drive power connector, with the computer off, but the power was still connected to the mains.

David.

[Rigger]

So if pin 14 is perminantly attached to ground the power supply would be "on" all the time?

That would mean the the on/off switch usually on the back of the ATX power supply used to actually kill the power could be used to control the power to the system? Or possibly be rewired to a normal botton at the front of the unit.