IBM AT power supply case/cooling question

From: Russ Blakeman <rhb57_at_vol.com>
Date: Mon Apr 29 16:40:35 2002

And to mention that the PS cover helps guide the airflow thru the heatsinks
and by leaving the cover off the fan isn't drawing the air through the
designed path. You can leave the lid off the PC without a problem but the PS
(as Toth states) is very dangerous and actually detrimental to the cooling
process. A better fan, in terms of more CFM pulled, is the better way to go.
I've pulled fans from old NCR microchannel machines that have variable
speed, controlled by a thermistor, that speeds the fan up when it gets
warmer and I know new ones are still being made.

-----Original Message-----
From: owner-classiccmp_at_classiccmp.org
[mailto:owner-classiccmp_at_classiccmp.org]On Behalf Of Tothwolf
Sent: Monday, April 29, 2002 3:38 PM
To: classiccmp_at_classiccmp.org
Subject: Re: IBM AT power supply case/cooling question


On Mon, 29 Apr 2002, Chad Fernandez wrote:

> My question is this..... can I safely leave the PS cover off? If I
> add a few of the factory screws the PS case/chassis is still quite
> solid, it just does have the cover on the top, or by the drives.
> Basically, it removes two out of six sides. I'd want to do this for a
> bit more cooling, since the fan would have less obstruction. Plus, I
> think it looks lind of cool too :-) Would I have problems with EMF
> emmisions effecting the computer's operations?

Leaving the cover off of the power supply would greatly increase the
chance of contacting one of the high voltage components in the supply.
Typically, there are voltages in excess of 300V in those types of
switching supplies. It is often present on the chopper's heatsink(s), and
at a potential to ground, since most of those supplies simply use a
voltage doubler on the mains voltage.

All that being said, I don't think leaving the cover off of the power
supply will help the cooling situation much, and would expose anyone
working on the system to the high voltages present in the supply.

> The main case cover would be installed.... would I have other EMF
> troubles, if I leave the top of the PS off?

There is a possibility of EMF troubles, but there is also the possibility
of RFI issues.

-Toth
Received on Mon Apr 29 2002 - 16:40:35 BST