Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!rutgers!rochester!uhura.cc.rochester.edu!afry
From: afry@uhura.cc.rochester.edu (Alan R. Fry)
Newsgroups: comp.sys.mac.hardware
Subject: Re: SE/30 screen flickers/no it doesn't/yes it does/...
Summary: Try reorienting the hard drive...
Message-ID: <14413@ur-cc.UUCP>
Date: 9 Jun 91 22:53:07 GMT
References: <12163@skye.cs.ed.ac.uk> <1991Jun8.223327.25416@spool.cs.wisc.edu> <1991Jun9.202517.14662@m.cs.uiuc.edu>
Organization: University of Rochester, Rochester NY
Lines: 39

In article <1991Jun9.202517.14662@m.cs.uiuc.edu> gillies@m.cs.uiuc.edu (Don Gillies) writes:
:>Another way to suppress stray electromagnetic activity is to take the
:>offending part (in this case, the hard disk) and enclose it completely
:>inside a metal shield (like tin foil).  I AM NOT recommending this,
:>merely pointing it out, since it may cause you hard disk to overheat
:>and fail.  However, if you think it can be shielded or at least
:>partially shielded without leading to overheating problems, then you
:>may want to try this method.  Make sure to test it before you bolt
:>everything back together.  In any event, foil could probably be used
:>briefly to determine that the electromagnetic interference was coming
:>from your hard disk.  Make sure you don't short anything out with the
:>tin foil.  

I responded to the original poster in this thread by e-mail, and my advice
was to simply re-orient the drive in the drive bracket.

I had the same flickering problem with my Quantum 105 (it was much worse
than the original poster's description of his problem), and the eventual
solution was to merely rotate the drive 180 degrees (so that I had to run
the scsi cable underneath the drive between the drive and bracket).  There
is still a very tiny flicker, but this seems to have solved the problem.
Perhaps another orientation (of the four possible orientaions, i.e.
controller card up/down with drive backwards/forwards) would work even
better.

I have heard of people using sheet metal to isolate the drive from the video
card (which seems to be the culprit in all of this flickering business).  I
have also heard that aluminum foil does not work well.  And the point you
made about over heating is certainly valid.  Anyway, I think re-orienting
the drive is a bit more practical (if it works!).

Cheers,

Alan
-- 
------------------------------------------------------------------------------
  Alan R Fry                   | Graffiti on a condom machine in San Fran:
  afry@uhura.cc.rochester.edu  | "Don't buy this gum, it tastes like old tires"
-------------------------------------------------------------------------------