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From: USERID@bunny.gte.com (Michael Hackney)
Newsgroups: comp.sys.apple2
Subject: Re: Unclaimed Sound Interrupt(08FF)
Message-ID: <9707@bunny.GTE.COM>
Date: 11 Sep 90 15:59:13 GMT
References: <1990Sep9.092749.23191@utstat.uucp>
Sender: news@GTE.COM
Distribution: na
Organization: GTEL
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As I mentioned earlier (~3 weeks ago) I have had the same problem.  Mine 
is DEFINITELY temperature related.  The increase in temperature is caused 
by any combination of:

1) insuffecient power supply
2) improper ventelation (poor fan, blocked air paths)
3) too many 'high power drain' cards - including RAM expansion slot cards.
4) outside air temperature

I almost never had errors in the winter (I keep my office COLD).  In the 
spring, summer and fall the frequency increased.  On really hot days, I 
couldn't even start up the computer and run it for 5 minutes without $08FF 
errors.

Then I discovered that the VBL chip (the socketed square chip) under the 
power supply was "loose".  When I pressed down on the chip, it would rock slightly.  I turned on the cmputer on a really hot day and WA LA, no $08FF errors!  Several weeks later they started cropping up again and I reseated the chip to eliminate them.  I went several months with occasionally reseating the chip.  Finally, I epoxied (rather harsh) the chip in place.  It has been a 
year now and I have not had a single $08FF error! 

I am a professional GS software developer and my computers are on about 20 
hours a day, 7 days a week.  I used to have days when I could not even use 
the GS without constant crashing.  I keep a can of "Instant Cold" spray handy (available at electronics supply stores).  If you suspect a hot chip problem, just zap the sucker to chill it off.

Michael Hackney
PiWare