Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!udel!rochester!uhura.cc.rochester.edu!afry
From: afry@uhura.cc.rochester.edu (Alan R. Fry)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Flickering SE/30 - I need a Doctor
Summary: Could be the hard disk or a bumped controller card.
Message-ID: <12698@ur-cc.UUCP>
Date: 10 Mar 91 07:49:17 GMT
References: <9103080021.AA01201@grus.cs.nps.navy.mil> <1991Mar8.162541.9578@ora.com>
Organization: University of Rochester, Rochester NY
Lines: 47

>Do any other SE/30 owners out there have this sort of flickering?  
>Even better, did any other SE/30 owners out there figure out how to
>fix it?  Please post.
>
>	-Linda Mui
>	lmui@ora.com

I had this very problem after I had a Quantum 105 HD installed by the dealer
where I bought my SE/30.  The screen flickered something fierce whenever the
hard disk was accessed.  The flickering occurred mostly in the lower part of 
the screen.  The dealer was clueless as to what to do about it, but he tried
the hard disk in another SE/30 and it also flickered.  I was pretty sure it
was the HD itself, so I called and talked to the folks I had ordered it from,
and I also called another mail order place to talk to their tech support 
people.  It turned out not to be the hard disk, exactly.

What I found out is that stray magnetic fields from the hard disk controller
tend to cause some serious interference in the SE/30 monitor card (I don't
if the same troubles occur in the SE, Plus, and Classic, but I suppose they
do.)  The solution was for me to open the sucker up and remove the HD from
the bracket, rotate it 180 degrees along the verical axis, and replace it in 
the bracket.  In order to do this, you have to run the SCSI cable underneath
the HD, between it and the bracket.  It seemed like a pretty flimsy fix, but 
almost all of the flickering went away.  What is left is barely noticable.

I have also heard of people who tried to construct Faraday cages (a closed 
metal casing) for their monitor conroller cards.  I hear that aluminum foil
doesn't work, but sheet metal does.  Be careful with those sharp metal corners
in high electric fields.  

One other bit of experience I had came when I was installing a hard disk in a
friend's SE.  There was no problem with the disk causing any flickering, but
after I installed it, the screen flickered all of the time.  What I decided
was the I must have bumped the monitor card when I had the case open, so
I opened it back up and (with the power off) wiggled the monitor card a
little (I can hear Apple Techs screaming).  This cured the problem.  If you
try this, be VERY gentle with your wiggles since the connection to the 
monitor yoke seems pretty unstable.

The root of the flickering problems seems to come from the monitor
controller card itself.  I don't know how much it would cost to get a 
replacement, but I would guess it would be a bundle.  For that matter, I'm 
not sure that getting a new one would fix the problem.

Hope this helps.

Alan