On Nov 8, 19:32, Tony Duell wrote:
> > I never had problems as you describe, nor have I ever heard of anyone
> > needing to adjust the alignment of an Apple disk drive.
>
> I have had to align Disk IIs. The version based on the SA400 mechanism,
> if there's more than 1 type. And it certainly appeared as though the
> continual banging of the head against the end stop (due to there being no
> track 0 sensor) was a contributory factor in them losing alignment.
I've had to do that too, and I tend to agree with Tony that the banging on
the end stop seems to contribute to the need. However, I ought to point
out that I've had to align lots of other 5.25" drives as well (I used to be
a (micro)computer technician, a long time ago), including ones that used
taut band mechanisms and leadscrews.
> > As far as I know, there is no procedure in the Disk ][ manual for
aligning
> > a drive, and as far as I know, there is no reason for needing one.
>
> There is no procedure in PC user manuals for aligning the floppy drives.
> Are you saying such a procedure does not exist? I have the service
> manuals for the Teac drives used in my PCs and they include alignment
> procedures.
As does the Apple Service Manual for the Apple ][, as sold to all Apple
Service Centres in the early '80s. It gives explicit instructions on head
alignment, and board setup.
I don't think I found Disk ][s to be much less reliable than contemporary
drives, and mine are still going strong (both pairs). We all learned to
open the door before power-up or power-down, but we had to do that with CBM
drives and many others too. Certainly some brands of disk were better than
others but that was true in the Commodore drives and the Cromemco drives,
and later in the Acorn/BBC drives as well. Most of the time, they were on
top of the machine, with the monitor on top of that, and I don't recall any
problems that could be ascribed to that.
The only catastrophic failures I can remember (apart from "Oh Spit! I meant
to format the *other* disk!") were due to users replacing the cables
wrongly. I think I've told this story before, but the Tech College used to
loan Apples out to staff over the weekends. Typically the drives would be
disconnected to make it easier to carry. It's easy to put that 20-pin
ribbon header back, one pin along from its correct position on the
controller, and if you do, you let a lot of magic white smoke out of the
drive door. You can tell it's magic smoke, because the drive never has
enough magic left to work after that. Usually the 74LS125 takes the brunt,
but at least once it took out the MC3470 as well. That was "interesting"
the first time, as Apple carried no spares, and the Motorola distributors
claimed it didn't exist.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Thu Nov 08 2001 - 16:36:07 GMT