Tim Hamel wrote:

> It's sort of the general spec of the ATX power supply along with a
> circuit to test; which I imagine could be modified.

> http://www.compute-aid.com/atxspec.html

  Nice reference.

  OK, I'll try *another* reply to this.  The previous *two* involved
opening my (ATX) PC case and investigating the MB connector.  I'm sure
I didn't touch anything with my wedding ring, but I certainly crashed
the machine.  There is a fault in there somewhere, but pragmatically,
the cover is going back on and it can stay there!

  It would appear that converting the ATX supply to "always-on" is as
simple as grounding the "PS-ON" (green; pin 14) wire.  It may be a good
idea to disconnect this from the motherboard - easily enough done by
extracting the Molex pin from the connector housing using a jeweller's
screwdriver to depress the retaining projection on the pin.  OK, so
maybe you need practice for that!

  I would suspect however it to be an open-collector output.

  By way of interest, the other wire colours to match that diagram are
black = Ground (pins 3,5,7,13,15,16,17), red = 5V (4,6,19,20), yellow =
12V (10), orange = 3.3V (1,2,11), blue =-12V (12), white = -5V (18),
grey = Power Good (8) and violet = Standby 5V (9).

  Whew!  Got the cover on without further mishap.
--
  Cheers,
        Paul B.