HP & 800BPI / was Re: Tape cleaner on eBay

Marc Verdiell marc.verdiell at gmail.com
Fri Oct 9 12:28:04 CDT 2015

I'm right in the middle of resuscitating an HP7970E (1600 bpi with the HP-IB
interface). The main problem I had so far was the rubber in the reel hubs
had completely fused to the tape reels that were left on the hubs. I had to
disassemble the hub locking mechanism and use lots of careful X-Acto knife
work to separate the two. A few tape rollers were rough or stuck - just
oiled them for now. Then it started to work, I am very surprised. There are
three red switches on the motor control board inside to make the tape go
forward, reverse and fast rewind. So it's pretty easy to test if the
transport works and the motor servos and tension arms move how they are
supposed to.

Wow, looked at your site, and you actually wrote a HP 2100 cross-assembler?
Nice. Would it work for the HP21MX too? Did you compile it using the command
line tools in XCode?


Date: Wed, 7 Oct 2015 13:29:37 -0700
From: Brent Hilpert <hilpert at cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
	<cctalk at classiccmp.org>
Subject: HP & 800BPI / was Re: Tape cleaner on eBay
Message-ID: <858603D2-2D79-45D6-993C-A8939D996815 at cs.ubc.ca>
Content-Type: text/plain; charset=us-ascii

On 2015-Oct-07, at 12:56 PM, Glen Slick wrote:
> I have an 800BPI 7970B in a 2113B rack system. I've never gotten 
> around to trying to get it up and running. Are they fairly reliable 
> drives to get going again? I don't have any other 800BPI drives to 
> write any tapes to read with it.

>On Wed, Oct 7, 2015 at 12:46 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
Well, the unit here was in pretty good physical condition as received.
It had a cascading failure in the capstan driver but it was a fairly
straightforward fix.
I think there was one sluggish/partially-seized pulley bearing (freed up
with some oil).
Pretty rugged drives as you know. I wonder about the capstan rubber in the
long term but I think that's about the only thing to worry about on age
I think bitsavers nowadays has manuals and schematics for the B version as
you have, years ago I had to do some reverse-engineering for the capstan
This page is over ten years old and needs some updating, but FWIW:
Note the tape drive repair log page linked there.

More information about the cctalk mailing list