Fan reversal on 3b1/7300

[Robert R. Andrews]

In article <804 at umbc3.UMD.EDU> motteler at umbc3.UMD.EDU (Howard E. Motteler) writes:
>In article <409 at flatline.UUCP>, erict at flatline.UUCP (eric townsend) writes:
>> 
>> Problem:  I live in an old, dusty house ... [much dust ommitted]
>> Solution (of a sort):  Reverse the fan and add a easily removeable filter.
>> Anybody tried this (and know an easy way to do it including Radio
>> Shack part #'s :-) ) / see any problems with doing this?
>
>A scrap of pantyhose stretched and taped over an intake grill makes an
>adequate filter for coarser types of particles, cat hair, etc.  I ran

[stuff about pantyhose and reversed fans removed]

>the mother board (warm air wants to rise, and you will be blowing it
>down, etc.), but reduced cooling was noticable.  I changed back
>after I got tired of warm air blowing over my fingers.
>
>						Howard Motteler

I used to work on a system that the keyboard was integrated with the monitor
and keyboard.  A big graphics station.  It had positive air pressure cooling.
The biggest problem was the air coming out of the keyboard.  Caused chapped
hands and tearing in your eyes.  We could only work at this system for about
an hour before you had to go get some moisturizer and rest the eyes.  Nothing
as fun as typing with dry, cracked fingers.  Finally solved by putting a 
separate negative pressure fan in the bottom of the keyboard.

Some boards are designed so that the most heat sensitive parts are first
cooled.  Changing the air flow could mess this completely.  Heat is a chips
worst enemy.  Static is second.  I think it best to assume the designer had
to think about that.  But my experience only not the designers.  Any comments
AT&T?

						Robert Andrews