troubleshooting an SA-400 disk drive

From: Peter Turnbull <pete_at_dunnington.u-net.com>
Date: Wed Jun 11 02:25:45 2003

On Jun 10, 22:23, Eric Chomko wrote:
> I have been monitoring this new problem for a few days. Actually,
> it first surfaced weeks ago, but I had zero time to look into it.
>
> Anyway, I have a three drive Smoke Signal Broadcasting disk system,
> in which one drive, 2 (last one on 0,1,2 chain), has this nasty whine
> when
> powered on. The other two drives work and sound fine.
>
> The faulty one's driver motor never stops when powered on whereas the
> other two do.

Sounds like the motor control board is faulty.

> The others must have the last one due to the terminator
> which functioned correctly in the chain. I have managed to pull the
bad
> drive and managed to get the two working ones to work with terminator
> resister moved to drive 1.

The terminator should be on whatever drive is last in the chain (the
end of the ribbon cable).

> I put 2's (bad drive) large electronics board
> onto 1's drive mechanism and it works fine. That leaves 2's drive
> mechanism
> as being bad; either the small circuit board or the drive motor.
> Also, when 2 is selected the red LED does light up, but no diskette
can
> be read.

Motors sometimes burn out, but other faults are relatively uncommon.
 These motors normally have three or four wires; two are the power, and
the other(s) are the tachometer signal back to the control board; this
tells the control board how fast the motor is going. The tacho may be
broken, but a faulty control board is more likely. If one of the other
drives uses the same motor you could try swapping, which at least would
tel you whether its the control board or the motor itself.

The whine is probably because the motor is running far too fast, and
that is why you can't read a disk. Don't let it run like this too long
or you'll damage the motor.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York
Received on Wed Jun 11 2003 - 02:25:45 BST

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