Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!ncar!hao.ucar.edu!moses
From: moses@hao.ucar.edu (Julie Moses)
Newsgroups: comp.sys.atari.st.tech
Subject: Hard Drive interferring w Mono Monitor. Solution Sought
Message-ID: <8905@ncar.ucar.edu>
Date: 21 Oct 90 06:14:00 GMT
Sender: news@ncar.ucar.edu
Reply-To: moses@hao.ucar.edu (Julie Moses)
Organization: High Altitude Observatory/NCAR, Boulder CO
Lines: 40

A fellow in our user group has a very unusual problem involving
his new external hard drive and his monochrome monitor.

The PROBLEM:
Copying of some files to or from his hard disk drive causes the
vertical sync on his monochrome monitor to be lost. 

The CONDITIONS are:

- Latest ICD host adapter and booter.
- Seagate ST177N drive.
- Any ST computer (we tested a couple).
- Only Monochrome monitors (we tested 3 monos). Problem does
  not exist when a color monitor is connected.

The files that are copied to/from the hard drive and cause the
vertical sync to be lost are successfully copied (even successive
files in a multiple copy). The files that cause the problem have
nothing in common; for example, one file is a desk accessory and
another is a resource file to a different program. These 'problem
files' (the problem is not the files but something to do with the
hardware) will cause the vertical sync on the mono monitor to be
lost everytime. With one file we were able to isolate a particular
block of the file as the culprit by saving the block as a new file.

Has anyone experienced this problem before? Does anyone have an
solution to the problem?

A technically inclined fellow in our ST community has been conferred
and he thinks that somehow these problem files have a bit pattern in
them that when transfered into or out of the hard drive create
interference with the vertical sync of a monochrome monitor.

The poor guy with this problem has lost 2 months getting his new
hard drive mechanism working. He has shipped it back and forth 
twice now. There was one other problem with this external hard drive
system that was finally solved by replacement but this remaining
problem is something really unusual indeed.

J. Moses