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From: piner@newton.physics.purdue.edu (Richard Piner)
Newsgroups: sci.electronics
Subject: hard disk stumpper
Keywords: puzzles
Message-ID: <3967@newton.physics.purdue.edu>
Date: 15 Aug 90 07:15:34 GMT
Distribution: na
Organization: Purdue Univ. Physics Dept, W.Lafayette, IN
Lines: 34

For those who don't like puzzles, hit "n" now.
I've got a real puzzle for the wizards of the net. I have an old hard
disk subsystem that is not working and I'll be damned if I can figure out
why. Here are the facts. Miniscribe 2012 (10 meg) hard drive connected to
a Xebec S1410 controller connected to a SASI host adapter.
The drive will not write, but I can read just fine.
The computer to SASI interface seems to be working correctly because
I can talk to the controller ok. The controller passes it's internal test
and tells the computer everything is fine. Control codes and data passed
between computer and controller all make sense. So I assume the interface
is working ok.
I happending to have a spare miniscribe, so I swapper disk drives. Same
results. I then ordered a spare controller board.
A side note, I got the Xebec controller from Computer Surplus Store.
They are listed in Computer Shopper. Thanks to everyone who responded
to my request for help locating this part. Well, the controller board
showed up today, and I swapper in the new board. No change. I can still
read the disk but not write to it. So, now I've tried two different disk
and two differenct controllers and it still does not write. So, I checked
all the wires in the connecting cables. Twice. They are fine. I checked
the power supply. Within spec, no ripple. I've tried formatting the drive,
this is a high level command for the Xebec. It goes off and tries to format
the drive, but just goes into a loop. After, resetting the system,
I can still read the old data, so format is not writting to the drive.
Clearly there is some problem between the controller and drive, but
I'm out of ideas. I'm stumped. I can't believe that I have two dead drives
with the exact same problem, or two dead controllers with the exact same
problem. The host to SASI interface seems to be communicating fine. Such
a simple thing either works or it doesn't. The power is ok and so are the
cables. I'm down to checking signals on chips, still I can find no problem.
Does anyone have a clue? Is there something I'm overlooking. Another
chap had a similar problem with a Xebec drive and posted here a couple of
weeks ago. Any progress?
				R. Piner