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From: callen@ada-uts.UUCP
Newsgroups: net.micro.mac
Subject: Re: Mac hardware problem
Message-ID: <27800001@ada-uts.UUCP>
Date: Mon, 28-Oct-85 09:25:00 EST
Article-I.D.: ada-uts.27800001
Posted: Mon Oct 28 09:25:00 1985
Date-Received: Fri, 1-Nov-85 02:08:58 EST
References: <3198@mhuxd.UUCP>
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Nf-ID: #R:mhuxd:-319800:ada-uts:27800001:000:1297
Nf-From: ada-uts!callen    Oct 28 09:25:00 1985


> About a month ago I completed the DDJ upgrade. Everything went well.
> A few days ago my mac quit. On power up the machine buzzes and
> displays 4 sad macs. The macs are located in the centre middle
> centre bottom. The two other macs are split at the edges of the
> screen and wrap around. The numbers under the sad mac vary but
> are either 04FFF8 or 020000 (or some variation).
> Anybody have any ideas?

I've done a half dozen DDJ upgrades and never seen THAT specific problem,
but I've had to shoot OTHER problems. They have (so far) ALL been caused
shorts between pins in the memory array (no comments about sloppy
soldering, please). Run the continuity tests listed in the DDJ article,
and check for shorts. Unfortunately, if you find a short and it involves
only the "common" lines in the array (which is nearly all of them), you
may have to pull ALL of those nice new sockets to find it (someone PLEASE
tell me that there is a better way...). Pull the sockets one at time and
re-test. So far I've been lucky - one short involved pin 14 (which nailed
it to a single chip), and the other was the second socket I pulled off the
board.

The DDJ upgrade is nice and cheap, but it's not for the fearful or the
novice soldering hacker...

Jerry Callen          ...ihnp4!inmet!ada-uts!callen