Re: I want to calibrate 5.25 inch floppy drives myself

[nparker@cie-2.uoregon.edu (Neil Parker)]

In article <robbie-3008561634280001@wopr.mindspring.com> robbie@mindspring.com
(Robbie Honerkamp) writes:
>In article <ericg-2509951337300001@ericg.cpd.tandem.com>,
>ericg@cpd.tandem.com wrote:
>> My wife teaches in a school that still uses Apple IIes and IIcs, and she has 
>> a lot of bad 5.25 inch floppy drives.  I'd like to clean and calibrate
>> them before sending them off to be repaired.  I'd like to try calibrating
>> them
>> myself.
>> 
>> I am an electrical engineer, so I have access to oscilloscopes and such,
>> but I do not have the calibration disk nor the procedure.  How can I get
>> these items?
>Copy II Plus has a disk speed disgnostic program. Also, Memorex (I think)
>used to put out a diagnostic disk that let you align and check the
>rotation speed on a 5.25" drive. It's been a looong time since I've
>worked on them, but if I remember correctly, the biggest problem with the 
>drives was the speed being off.. It's fairly easy to set the speed, there's
>a screw on the drive that you can adjust while running the CII+ program..
>
>Anyone remember which screw it is?

If the drive is an original Disk ][ (the one with the beige metal case and
the black plastic front), then you can find the speed adjustment screw on
the small vertically-mounted circuit board at the back of the drive.  It's
attached to a small ceramic box, sticking out from one side of the circuit
board.

Note that you have to take the case off to get to the circuit board and the
screw.

On newer drives (the ones with the all-plastic cases), the speed adjustment
screw appears to be accessible through a small hole on the bottom of the
case, right next to one of the rubber feet.  (You'll need a screwdriver
with a very small shaft to fit in that itty-bitty hole.)


If you can't find Copy II Plus, or some other program that includes a disk
speed tester, it is possible to test the rotation speed without any special
software at all.  To find out how, point your Web browser at
http://www.ugcs.caltech.edu/~nathan/a2tech/disk.spd.html.

              - Neil Parker
-- 
Neil Parker, nparker@{cie-2,cie}.uoregon.edu, http://cie-2.uoregon.edu/~nparker

                     "Bad move, Neil!"  -- The Tick