Date   : Sat, 14 Jul 1990 14:43:47 GMT
From   : cs.utexas.edu!texbell!texsun!digi.lonestar.org!harlie!mitch@tut.cis.ohio-state.edu (Mitch Mitchell)
Subject: How do I align a disk drive?

In article <XX000118c2@pallio.UUCP>, dg@pallio.UUCP (David Goodenough) writes:

>I recently got an old computer with a pair of full height 5.25" drives in
>it. One of them is out of alignment because disks formatted in this drive
>can't be read by the other (or any other 5.25" drive in the house), and
>disks formatted by a good drive (of which I have several), can't be read
>by the bad drive. For those that are interested, the drives are made by
>Tandon, and use a split band actuator to move the heads.

David - you might also want to check that the drive's rotational speed
is up to spec.  I had two 5 1/4" floppys that could format disks for themselves
but no other drives could read them.  I found that the rotational speed was
off by about 5 milliseconds.  It should be about 200ms between index pulses.
Once adjusted (via a potentiometer on the circuit board) the drives worked
fine.  I used some diagnostic software that came with my computer but an
o-scope or counter or mabe even seat-of-the-pants adjustment while trying to
read a good disk would work...

                               Good luck,

                               Mitch

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