Re: DRIVE SPEED

[dalloff@freenet.columbus.oh.us (Dave Althoff)]

Michael A Chambers (chambers@plains.nodak.edu) wrote:
: Can someone tell me how to calibrate the drive speed of a unidisk on an 
: apple //c

Internal or external?

The UniDisk 5.25/Apple 5.25 Drive is not fun to disassemble.  Especially
if it is inside your //c.  Fortunately, you don't have to.

You will need a speed adjustment utility (built into the better copy
programs), and a really tiny flathead screwdriver.

On the external drive, you are looking for a small round hole located on
the bottom, about two inches back from the front of the drive, on the
left-hand (with the drive upside-down) side, about an inch from the edge. 
On my drive, this is right next to the little rubber foot.  Grab a
flashlight and shine it down into the hole, and you can see the adjustment
screw.

On the //c internal drive, there is also an adjustment hole, which should
be in about the same place.  That would be about 2" from the
disk-drive-side of the machine, and at least an inch from the back panel;
probably a little further.  Again, if you peer into the hole, you can see
the screwdriver slot in the end of the trim pot.

Run your utility program, and carefully adjust the trimmer until the drive
is in spec.  Note that a little turn goes a long way, even though it is
about a 20-turn pot.

Caveat:  Do not attempt to adjust the speed of a 3.5" drive.  I don't even
know if it is possible to adjust those drives; if it is, I have never seen
a procedure for doing it.  You didn't say you have a //c+, so I presume
you are talking about adjusting 5.25" drives.

]Dave Althoff, ][.
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