HP-85A tape drive conversion

Jay West jwest at classiccmp.org
Tue Mar 31 06:20:04 CDT 2015

So the roller on my -85A tape drive is marginally ok, but finding the tapes
for that which work reliably is not really an option. So I was going to
attempt the conversion to make the drive use DC2000 tapes.


Marc - thanks for the great video of this process at


The process basically involves making the capstan roller "taller". Marc's
approach is to use a lathe and fabricate a taller capstan roller and he
suggests using heat shrink tubing to make the capstan roller taller as an
alternative. I do not have a lathe, so the first option is out. While the
second option would work, according to the video it "just barely makes the
capstan roller contact the bottom portion of the tape capstan wheel". That
concerns me, as if it's "barely making contact" I'm concerned that over time
this would wear the capstan roller motor shaft and perhaps wear down the
wheel, not to mention potential vibration.


So. two questions: What SHOULD the outer diameter of a good capstan roller
be on that drive, and does anyone have other suggestions for how to make the
capstan roller "taller"?



More information about the cctalk mailing list