My new toy: HP85

From: Stan Perkins <stan_at_netcom.com>
Date: Wed Jun 9 17:09:56 1999

Tony Duell wrote:
>
> > > I havn't powered the thing up yet, but apparently it runs BASIC. It
> > > has a printer and what looks like a tape slot.
> >
> > If you also have same tapes, do *NOT* insert any tape that you
> > value ihto the tape drive yet! The capstan rubber on those drives
> > generally has turned to goo by now, which will come off and coat the
> > tape you insert, ruining the tape! Joe Rigdon and Stan Perkins
>
> Well, it'll coat the 'drive puck' in the tape cartridge, not the tape
> itself. It is normally possible to take the cartridges to bits and clean
> the drive puck if this happens, although it's a fiddly job, and normally
> only worth doing if the tape contains valuable data (or you're insane).

Actually, if the drive wheel is gooey enough, it will smear goo onto the
tape itself and make the cartridge almost impossible to clean.

There's a significant problem with the original DC100 tapes as used in
the HP-85, HP 9825, etc. The oxide tends to flake off the backing and
this not only destroys the data (usually it's the catalog at the
beginning of the tape, since most tapes are stored in the rewound
condition), but also the now clear tape confuses the EOT photodetectors.
With repeated attempts to read the catalog and/or rewind the tape
eventually you will unspool the cartridge. Not fatal, but a pretty good
indication that the tape is unusable.

>
> Has anyone got a procedure for rebuilding HP85 tape drive rollers? I've
> got fixing HP9100 magnetic card reader rollers down to a fine art now,
> and it only takes me an hour or two to do one. But I have made a couple
> of special tools to get the old roller off and press the new one one
> without damaging the motor.
>
> -tony

The procedure I've used on several of the HP tape drives involves:

1) Removing the drive assembly from the computer
2) Carefully removing the motor and capstan assembly from the housing
3) Scraping the leftover goo from the aluminum hub
4) Shrinking three layers of heat-shrink tubing over the bare hub
5) Trimming the excess tubing, and
6) Carefully reassembling the mechanism and reinstalling it.

I've done this procedure on about ten drives, and it now takes me about
30 to 45 minutes, start to finish (but don't ask how long the *first*
one took me!).

Stan
Received on Wed Jun 09 1999 - 17:09:56 BST