How to turn on AT power supply?

[root]

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

 

[Bryce]

root wrote:

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

I think they just need a minimum load ... a hard drive
ought to do the job.

 

[Sofa Slug]

root wrote:

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

The way I understand it (and I could be wrong), is that an AT supply
works differently than the ATX version. It outputs a 5v "power good"
signal to turn on the motherboard only after the supply's self check has
verified that all it's DC outputs are within spec.

I suspect that if an AT supply sees the correct load, it should work.
Unless you have a load on all the outputs, you would either have to use
a PC as a load, or construct an external load out of resistors.

See:

http://www.pcguide.com/vb/archive/index.php/t-5939.html

and...

http://www.scotsmist.co.uk/power_supply2.html
http://www.informit.com/articles/article.aspx?p=31105&seqNum=4

 

[root]

Bryce <invalid@invalid.invalid> wrote:

root wrote:

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

I think they just need a minimum load ... a hard drive
ought to do the job.

Thanks for responding. I just didn't pay close enough
attention: the AT and ATX supplies use the same pins
to turn on, the wire colors are not the same across
brands. For the record, if you hold P1 with the catch
on the top and the pins facing you, you connect pins
3,4 on the top row counting from the left.

These power supplies are useful for other sources on
the bench.

 

[Meat Plow]

On Wed, 03 Jun 2009 16:59:31 GMT, root <NoEMail@home.org>wrote:

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

Put a drive on it. Floppy will do.

 

[Andy Cuffe]

On Wed, 03 Jun 2009 16:59:31 GMT, root <NoEMail@home.org> wrote:

I know I can turn on an ATX power supply by connecting
the green wire to the black wire next to it. This
doesn't work for the older AT power supplies. What
is the trick for them?

TIA

There's no turn on pin on an AT power supply. There's just an AC
power switch. It may shut down if there's no load on it.
Andy Cuffe

acuffe@gmail.com