Date   : Fri, 22 Jan 1988 00:19:14 EST
From   : "Mark E. Becker" <MBECK@AI.AI.MIT.EDU>
Subject: Need help with floppy drive powerdown problem

Hello All -

     I'm sure someone out there has solved this problem.. it has
bitten me enough so that I'm now out searching for a solution.

     The configuration:

       2 Shugart 851 8" DS/DD drives.
       2 NEC FD-1036A 3.5" DS/DD drives.

The problem -

     Turning off power to these drives causes the on-board electronics
to "spasm" and write random magnetic garbage on whatever diskette in
installed.  Of course, the doors are closed.  In the case of the
851's, the heads briefly load then unload... the 3.5's spin for a
second or two until the power supply drops below some critical
voltage.

     The garbage only appears on a cylinder segment; the cylinder
being where the two heads are at when the power drops.

     I can usually "fix" the 8" disks by re-formatting just the
affected cylinder and reloading the damaged files from backup.
However, the 3.5" disks resist this and I had to degauss and then
re-format.

     Hardware hacks to solve this problem would be appreciated.

Regards,
Mark Becker
MBECK@AI.AI.MIT.EDU