" wrote:
I have this power supply we stripped out of a pc we're junking. It
has a 12V 10A section. I would like to use it as a 12V bench supply
for testing and running equipment. I have no plans for the other
supplies. Can I run it and the other supplies unloaded? And can I just
use the 12V supply without using the others? The unit presently won't
come on but there is a green wire in the bundle with the mother board
connector that I suspect needs some kind of proper bias on it but I'm
not sure. Does anyone have any information on this?

There are two kinds of PC power supplies. The original or "AT" supplies
which turn on and off by a switch and the newer ones called "ATX" which
turn on and off by the computer.

If the power plugs for the motherboard are seperate, you have an AT
supply, if they are one 20 or 24 pin plug, you have an ATX. Some have
both.

In order to turn on an ATX power supply, you need to short two leads on
the plug. This is well documented, STFW for "testing ATX power supply".

I have not done this with ATX supplies, but I have used AT supplies as
5 and 12 volt power supplies. Most of them require a load on the 5 volt
side, when I used one to power a 12 volt radio, I put an automobile tail
light bulb across the 5 volt leads. It drew enough current to keep the
supply active.

Note that while the DC voltage is quite clean, it is a switching power
supply and many of them have lots of RF noise on the DC leads. I had no
trouble using it for a VHF rig in a mixed HF/VHF environment, but many
people have complained about using them on HF rigs.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/