Re: Need help solving Zip Drive mystery

[Rubywand <rubywand@swbell.net>]

Supertimer writes ...
> 
> I'm trying to help an Apple IIGS user set up a Zip drive.
> The problem is that his setup is not working.
> 
> He has an Apple High Speed SCSI card.  There are
> other drives on the system.  Termination is correct
> and SCSI IDs are unique for each device and the card.
> 
> The hard drives on the SCSI chain show up but the
> Zip disks are not recognized.  ADU momentarily shows
> the unformatted Zip disk, but then progresses to the
> next volume before any selection can be made.
> 
> He boots up the system with the Zip disk in the drive.
> If he ejects the Zip disk at Finder and reinserts it, the
> computer freezes.
> 
> Also, in open and save dialog boxes, the computer
> is constantly polling his drives.  This is the same
> behavior as on my IIGS with HS SCSI card when there
> is NO Zip disk in the drive but the Zip drive is on.  On
> my system, inserting a Zip disk stops the polling.  If
> the Zip disk is blank, the computer asks "Eject or
> Format" on my system.  There is no such message
> on his system.
> 
> He has tried his Zip drive on another IIGS with the
> same results.
> 
> Any idea what's going on?  Could the Zip drive have
> been DOA?  If so, what's the typical signs?
> 
> He is using DOS formatted Zip disks.  The IIGS takes
> these fine on my system and can be reformatted and
> partitioned easily.  That's not the case with his system
> and drive.


     Our first Zip Drive was bad. This showed up as failure to perform reliable
disk accesses (which, in turn, led to a lot of clattering to do re-tries).  The
drive was, from the start, noticably noisy (sort of hard to quntify) and it
ejected disks nearly completely (instead of an inch or so for the good
replacement).

     So; while the drive may be defective, the symptoms you describe do not match
my only experience with a bad (pure-SCSI) Zip Drive.

     Assuming the System software, drivers, ... are okay, the symptoms sound like
a SCSI ID or device recognition problem. This may indicate a defect in one of the
SCSI cables or in the interface of one of the connected devices. (Possibly, one of
the cables between the Zip Drive and GS does not pass through ID 5 or 6. Or, the
user might just need to flick the Zip Drive's SCSI ID switch back and forth a few
times to make a good contact.)

     What happens if the user boots a nearly bare bones System from diskette with
just the Zip Drive connected? Yes, with an unmodified Apple HSS, there would be no
termination power. However, Zip Drives have short cables and employ a light
termination load. The Drive might work or, at least, be recognized. If it does,
you would know that, probably, something about connection with the other drives is
causing problems.

     A variation of the above is connecting the Zip Drive and just one other SCSI
device which could supply termination power and, perhaps, boot System.




Rubywand