Re: SCSI Hard Drive Mechanisms

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4ni0ef$ps0@nps.navy.mil>,
Mark A. Schooley <schooley@nps.navy.mil> wrote:
> 
> My Quality Computer Q-Drive 100 has recently stopped working
> and I am pretty sure that it is the drive mechanism that is
> at fault.
> 
> My question is:
>   Can I replace the Conner Drive Mechanism with any other
> SCSI drive and use the rest of the drive (i.e. enclosure,
> powersupply, connectors, etc.) or do I need to purchase an
> entire external drive setup?

In most cases, yes.  The main problems you are likely to run into:

1. Difference in mounting requirements.  Older mechanisms are likely
   to be 5.25" drives, while newer ones will nearly always be 3.5",
   possibly smaller profile as well.  You may need some kind of mounting
   bracket to attach the new mechanism.

2. The SCSI ID selector provided by the case may be incompatible with the
   connectors provided by the new mechanism.  At worst, this will require
   that you use jumpers on the drive to set the SCSI ID, rather than the
   external selector.  At best, you might be able to modify the connector.

3. Similar problems may occur with any drive access light - the connector
   could be a different type.  This is usually easier to fix.

4. Older cases might have a weak power supply, which doesn't meet the
   requirements of a newer drive.

   To give an extreme example of this: I recently tried using a 9 GB drive
   on a IIgs (a Seagate, I believe), which had already been tried on a
   Mac.  It was a full height 5.25" mechanism, placed in a case which
   had a moderately good power supply, but it wasn't rated high enough
   to provide the startup current required by the mechanism.  The drive
   was not able to be accessed.  It was later moved to a case with a
   larger power supply, and it worked fine (not tried on the IIgs, though).
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand