Fan Direction (was: Re: PC floppy cable twists...)

Mark Tapley mtapley at swri.edu
Fri Oct 21 13:24:57 CDT 2005


At 6:09 -0500 10/21/05, Allison wrote:
>....  All of my systems
>cooling and air flow get attention even if it requires some card stock
>and tape duct work.  Fans blow in and filters keep cat hair and
>other deutrius from getting in those places where it's going to do bad
>things. I find that tends to keep the inside of my PCs clean too. I
>turn the fan around and add a filter. Beats having a hairball clogging
>the cpu fan and crashing the system.

<see my previous posting, somewhere back in the archives...>
	Although this in general is a good idea, it doesn't always 
work. NeXT cubes were  designed with the fan exhausting air, so the 
crapola sucked in through the optical drive slot wiped out the 
optical drive before long. NeXT eventually approved the procedure to 
mechanically turn the fan around (do *NOT* simply reverse the 
connector).
	Problem is the designers actually did do _some_ thinking. On 
its way out the fan in the original configuration, the air went over 
the logic board(s) first, then the power supply and drives last. 
Reverse the fan, it's now hot air hitting the logic board. On my 
system, this caused the SCSI controller to fail occasionally.
	Solution in my case was to put the fan back to its original 
configuration, then tape over the floppy and optical cut-outs on the 
front of the case. (N.B. my system may be unique in that the floppy 
is mounted with a custom mount to an optical-sized cutout, with no 
attempt to seal well. It may be that either taping or reversing the 
fan would have solved the problem.)
-- 
					- Mark
			210-522-6025, temporary cell 240-375-2995



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