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From: mvolo@ecsvax.uncecs.edu (Michael R. Volow)
Newsgroups: comp.sys.att,comp.sys.ibm.pc
Subject: Re: failing memory in AT&T 6300's
Summary: most likely a surge you were unaware of
Message-ID: <5821@ecsvax.uncecs.edu>
Date: 12 Nov 88 19:27:17 GMT
References: <61050O05@PSUVM>
Organization: UNC Educational Computing Service
Lines: 30

In article <61050O05@PSUVM>, O05@PSUVM.BITNET writes:
> I have a lab of 20 AT&T PC6300's.  They have been doing fine, and just
> two weeks ago, I started having problems with memory.  Little to my
> liking, the chips are soldered on a memory expansion board.  Why AT&T
> chose this route, I'll never know, but that doesn't matter.
> 
> Does anyone out there know what might cause 4 machines to develop the same
> memory symptoms at the same time.  To the best of my knowledge, no spikes,
> surges, etc have gone through the room.  It seems to be located in the bank
> between 256 and 384k  which would make it the first bank on the memory
> expansion card after the 256 on the motherboard.
> 
>                                           (215) 320-4819


Not sure it this is an answer to you problem, but here goes.  I had
a direct lightning hit on my house, entering the house wiring and the
phone lines both.  The surge appeared to enter my computer (had surge
protector) through the phone line --> modem --> serial port --> bus!!
Needless to say everything closest to the bus was zapped (modem, com1,
parallel port, accessory switch on monitor, printer interface chips..
.....).  I wonder if something like this happened to your AT&T's.
Were the four computers with memory damage near each other on the cir-
cuit?  It sounds like the damaged chips were those closest to the bus.
I/O lines are royal roads into the guts of the computer and are most
often totally unprotected from surges (unless you have a modem surge
protector).  Don't know whether this applies to your situation or 
not.

M Volow, VA Medical Center, Durham, NC    mvolo@ecsvax