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From: kraut@ut-ngp.UUCP (Werner Uhrig)
Newsgroups: comp.misc,comp.sys.mac
Subject: hardware fix to twitching screens
Message-ID: <6019@ut-ngp.UUCP>
Date: Mon, 24-Aug-87 20:32:58 EDT
Article-I.D.: ut-ngp.6019
Posted: Mon Aug 24 20:32:58 1987
Date-Received: Tue, 25-Aug-87 06:48:23 EDT
References: <5180@ihlpa.ATT.COM> <135@stech.UUCP> <6014@ut-ngp.UUCP>
Organization: UTexas Computation Center, Austin, Texas
Lines: 26
Summary: reheat cold solder at connectors
Xref: mnetor comp.misc:1102 comp.sys.mac:5961

In article <6014@ut-ngp.UUCP>, wmartin@ut-ngp.UUCP (Wiley Sanders) writes:
> >Normal?  No way.  The symptoms you describe are generally associated with
.....
>    Not normal but not unusual. Judging from the traffic on this newsgroup,
> a _lot_ of Macs have failed this way. Also, I don't think there is any
> adjustment that can be made that will get rid of the twitching screen.
> You just have to wait until it fails completely or else is so bad you
> can't stand it any more, then gat another board. I know

very often it turns out that the problem can be fixed with little work
(local repairshops still have been charging $150 for it, without mercy).

WARNING: do not try to repair your Mac internals if you don't know how
to prevent damaging it or yourself !!!

there is a 4-wire connector with a little latch which connects to the analog
board in the top left corner (looking at the board from the inside of the Mac.
these 4-wires connect to the CRT-yoke controlling horizontal and vertical
deflection.  The analog board tends to get so HOT at this connector that the
solder tends to heat up to such a degree that cold solder-connections can
develop.  The fix is to reheat and recreate a GOOD connection and to get a
fan to prevent such problems in the future.  I have fixed several boards this
way already ......

-- 
kraut@ngp.utexas.edu