[Coco] FD-501 Service Manual

Stephen Castello srcastello at gmail.com
Tue Feb 5 09:46:24 EST 2019

Make sure the IBM drive isn't a 1.2mb drive.  One of the differences
is the tracks for that drive will be skinnier than a 360Kb drive.

On Tue, 5 Feb 2019 09:31:08 -0500, Frank Thompson
<frank.thompson.iv at gmail.com> had a flock of green cheek conures
squawk out:

>I'm looking for a copy (digital or physical) of a service manual for the
>CoCo floppy drives.  I recently picked up a really nice FD-501 drive and
>controller.  I have an older generation coco floppy drive (the generation
>just prior to the FD-501) that includes two drives (the original as drive
>0, and an IBM labeled drive as drive 1).
>My problem is that disks made using the upper drive (the IBM drive) of my
>old unit won't always work on the lower drive (which reads disks made on my
>new FD-501 drive just fine).  The disks read fine on my new FD-501 drive.
>I've tried the process of elimination with formatting and creating a backup
>disk with each of the drives, but I don't get a result that indicates to me
>which drive is definitely the culprit.  (The IBM drive reads disks made on
>either of the other drives)
>I set/confirmed the drive speed using flourescent lamp illumination of the
>checker pattern on the bottom of the motor (60 Hz scale).  Assuming that
>this is accurate (given the tolerance of the line frequency of my household
>AC) I'd like to check the tracking adjustment.
>I've not been able to really find information on the official process for
>adjusting the head tracking.  Thinking about it, it seems like I would
>adjust the tracking to achieve the highest amplitude of an analog signal at
>some point in the signal path on the drive PCB.  I really don't know, but I
>have an oscilloscope and the desire to learn (and drives that don't all
>play well together).
>Thanks in advance for any info the group can provide.



. . . . File not found. Should I fake it? Y/N

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