Shugart 800 spindle bearings (Re: Shugart 800-8 media centering problem)

Jay Jaeger cube1 at
Mon Aug 17 16:22:44 CDT 2015

Well, in the process of repairing the Altos power supply I managed to
break the center lead off of the TIP31A that feeds the 2N3055 series
pass transistor.  This time, I need to order parts.

In the meantime, I swapped drives to make the problem more drive accessible.

Also, the Shugart 801 drive I was testing is part of a pair in a Data
Systems ADS-440 dual floppy system intended for use in a PDP-11 that I
have never used.  (Would have to look - looks like it needs its own
special interface card).  Along with that machine, which came from or
was at least touched by the U. Wisconsin Instrumentation Systems Center
(ISC) back in the day, came a set of (gasp) brand spanking new bearings
for a Shugart 8" drive.  Looking at the parts diagram, I think I'll pull
the spindle apart while waiting for my power supply parts, and see how
hard it would be to replace the bearings.  Not all that hard, I'd think.

For future reference, the bearings are:

Part #9 in the diagram - flanged bearing markings:
   SSR - 4HH    NMB

Part #8:  - (unflanged) bearing markings

NMB still exists as part of Minebea Mineature ball bearings.
NHBB still exists - New Hampshire Ball Bearings

The new old stock bearings are a little stiff, but will roll when held
against a piece of paper.


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