Re: Platinum 5.25" drive problem

[mjmahon@aol.com (Michael J. Mahon)]

Brian K. Lambert asked:

>I have an American Micro Research 5.25" drive which was doing something
>similar, w/ respect to the speed jumping erratically.  I took the cover
>off the drive... turns out it was caused by the disk itself periodically
>slipping from the grasp of the drive motor.  This was really hard to see
>at first, you have to watch it closely.
>
>I can get it to work by placing pressure on the lever which you close
>after inserting the disk, thereby increasing the friction between the
>drive mechanism and the disk.
>
>I thought it was because the inner ring of the disk was worn out, but the
>same thing happens with relatively new disks.
>
>Has anyone else seen had this experience?  Any suggestions for safely
>improving the grasp that the mechanism has on the disk?

There are two possibilities for the disk spindle slipping.  The first is that
the disk clamping mechanism has weakened through use or age and is
no longer applying sufficient clamping force.  Fixing this would be a
mechanic's delight, and dependent upon the specific mechanism.

The second possibility is somewhat easier to deal with, assuming that
not too many disks are affected.  (What you said about having the same
problem with several (?) "newer disks" causes me to suspect that your
problem may be of the first kind, and not the second kind we're talking
about.)  In the second case, the problem is excessive friction between
the disk and its plastic cover.  This can be fixed (in almost every case)
by carefully sliding the edges of the diskette over the corner of a desk,
avoiding the notches and not touching the exposed disk surface in the
process.  Moderate pressure while sliding will cause the plastic cover
to "expand" away from the disk, greatly reducing the friction.  If this was
the problem, the disk can then be used in the drive without slippage.

-michael

 Email:  mjmahon@aol.com
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