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From: eve@ssc-bee.UUCP (Michael Eve)
Newsgroups: net.micro
Subject: Re: Q: Turning machines on/off frequently
Message-ID: <190@ssc-bee.UUCP>
Date: Tue, 11-Sep-84 12:00:08 EDT
Article-I.D.: ssc-bee.190
Posted: Tue Sep 11 12:00:08 1984
Date-Received: Fri, 14-Sep-84 20:26:37 EDT
References: <13200@sri-arpa.UUCP>
Organization: Boeing Aerospace, Seattle
Lines: 36


	I tried to find the answer to this question myself, but
	couldn't find any reliablitity data which made sense to
	me.   

	What I did find indicated that once a chip was pass the
	infant mortality stage (100 hours or so), the chip became
	virtually immortal if run continuously.  Data was scanty
	but I got the impression (reinforced by my preconceived
	ideas?) that thermal cycling (on and off) was a major factor
	contributing to lead breakage within the chip.

	I became interested in this when my Apple started dying 
	once a week after 3 years of heavy use and being turned
	on and off several times daily.  It rarely died while
	in use, but would often refuse to boot up when restarted.

	After replacing several chips, I now leave my Apple on all
	the time.  Sometimes I will now go two months between uses
	and the machine would still be up and running.

	caveat: Within the past 2 weeks, the machine has again become 
	flakey.  This time I found just moving RAM chips around (not replacing
	them) will make it work for another day or two.  I wonder if 
	oxidation of the pins from continuous use is now catching up
	to me. (The older Apples run very warm.)

	mike eve       ssc-vax!eve@ssc-bee


	p.s: I originally submitted this as a reply, but it was returned
	undelivered so I have now made it a followup--maybe somebody is
	interested.
-- 
Mike Eve     ssc-vax!eve