Re: Apple IIGS Cooling

["Paul G." <carbide@egine.com>]

On Apr 10, 11:46 am, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Paul G. wrote:
> > On Apr 9, 7:52 am, Wolfgang <w...@work.com> wrote:
>
> >>I also removed the aluminum top of the power supply as I figured out
> >>that the most heat is generated to the rear end of the power supply but
> >>the vent mounting is at the front and does not give good air circulation
> >>in the back.
>
> > Yes, the whole IIGS is not designed to cool well.  It's easy to blow
> > air around inside, but what you really need to do is draw cool air in
> > and exhaust the warm air. I ended up using a fan mounted to the
> > powersupply  and a strip of foam between the powersupply and the lid
> > so that the hot air from the P/S is forced to exit out the top.  Since
> > the vents in the lid are so small the natural tendency is for the fan
> > to simply move the air in a nearly closed loop, getting hotter with
> > each cycle.  Over time, this dries out the electrolytic capacitors,
> > and your P/S fails.
>
> This is why a fan that sucks air out of the top of the case is so
> effective, relative to internal fans.
>
> A "laptop cooler" USB fan (usually actually two fans in a 3/8" thick
> case) placed upside down over the top of the case can accomplish so
> much, while remaining practically silent and using less than 200mA
> of +5v power (less than one Watt).

That would be helpful, certainly, but doesn't provide positive
ventilation to the P/S and the path of least resistance is again going
to be a loop. The frustrating thing is that the IIGS case is like a
bathtub. The slots in the lid provide what little ventilation there
is.  I put another strip of foam front-to-back, just right of the P/S
on the outside of the lid in an attempt to route the hot air to the
left, so it wouldn't just get pulled back in on the right side.
-Paul