18 Aug
2015
18 Aug
'15
2:48 a.m.
The bearings were actually easy to replace, no special tools required.
The hardest part was getting off the nut that was holding the spindle
together.
Other than that, the bearings side into place pretty easily (the top
one, which is the most critical, required the heel of my hand to press
it in place in the hole in the deck, that was all).
The whole operation took only about an hour, from start to finish.
For future reference, the original bearings are marked similarly to the
replacements:
Top bearing (with flange):
SSR - 4ZZ NMB
Bottom bearing (no flange)
NHBB R4
(It is possible that the replacement bottom bearing had that "R4" as
well, and I missed it).
Once I get the power supply fixed, I'll test the drive to see if this
helped. If there is ANY difference, maybe I can move a
shaft/screwdriver inserted in the old bearings just a little bit further
from vertical - they allow a tiny bit more rock.
JRJ
On 8/17/2015 4:22 PM, Jay Jaeger wrote:
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
NHBB
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.
JRJ