Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!brutus.cs.uiuc.edu!apple!coherent!dplatt
From: dplatt@coherent.com (Dave Platt)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Apple CD-ROM Self Help
Message-ID: <46873@improper.coherent.com>
Date: 15 Feb 90 21:40:06 GMT
References: <18201.635020296@ics.uci.edu>
Reply-To: dplatt@coherent.com (Dave Platt)
Organization: Coherent Thought Inc., Palo Alto CA
Lines: 50

In article <18201.635020296@ics.uci.edu> truesdel@ICS.UCI.EDU (Scott Truesdell) writes:
> 
> Well, our Apple CD-ROM finally started getting flakey, just like all
> the rest. It started refusing to mount "Phil and Dave's Excellent CD".
> This is a state that could not be allowed to continue.  
> Here's what I did...

> ... Use clean "canned air" to blast away at the CS drive from all angles.
> Also clean the entire interior of the enclosure. 
> 
> Reassembly is the reverse of disassembly. DO NOT reconnect the fan.
> Apple's "fix" is to leave this fan disconnected. It will cut down 
> on the amount of dust drawn into the device. I believe 'em. Ever 
> disassemble an 3 year old Mac Plus next to a 1 year old Mac SE?
> The Mac Plus is remarkably clean compaired to the SE.

There's another approach possible... one which probably isn't needed
with the Apple CD-ROM drive (which doesn't generate much heat) but
which may be very important in some other drive-boxes.  It's a trick
I learned from a fan-manufacturer's catalog...

[1] Reverse the fan, so that it blows air cool _into_ the case rather
    than sucking warm air out of the case.

[2] Tape a dust-filter across the fan opening.

This trick will pressurize the interior of the case with filtered air.
It moves the same amount of air as an evacuation fan.. but the air
passing across the internal components is largely dust-free... you get
cooling without running the risk of dust deposition.

I've heard reports that some people have had problems with the Mac IIcx
and IIci, because the fan draws a lot of air in through the diskette
slots... reportedly causing the diskette-drive heads to become cruddy,
and eventually fail.  It might make sense to reverse the airmover in
the IIcx/ci case, and tape a dust-filter across the vent slots... thus
causing clean air to flow _out_ through the diskette drive, rather than
pulling dust-laden air _into_ the case.

You should probably plan on cleaning the inside of _any_ fan-cooled
equipment periodically.  Our Sun shoebox disks do have dust-filters
in the air inlets... and they still do become somewhat dusty after a year
or so of constant use. [The shoeboxes with cartridge-tape drives get
MUCH cruddier than those without, as the tape slots permit unfiltered
air to enter the enclosure.]
-- 
Dave Platt                                             VOICE: (415) 493-8805
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