HP 9144A tape drive unit.

[Michael Maurice]

This unit was brought to me to repair because it wasn't reading tapes and coming up with a fault code.

I have to say I cant tell you if the fault is with the tape or the machine but at one stage it chewed the tape.

Does anyone know anything about these machines or the tapes?

The unit is part of a printing machine that is running 24 hours a day 6 days a week.

Here are some pictures

[paulsherwin]

It's a mid 80s QIC drive, more or less conforming to the 60MB DC600 standard (I'm not sure how compatible it is). The capstan wheels are known to go bad on old QIC drives and can sometimes be fixed/bodged by retyreing with a rubber grommet or O ring.

If I had a mission critical system that relied on one of these drives I don't think I'd ever sleep at night.

[Michael Maurice]

The rubber on the capstan appears OK, but I glued it in place to make sure, not so sure about the rubber in the cassette itself

[paulsherwin]

Have you tried a different tape cartridge? They do wear out quite quickly if used intensively.

Is the interface SCSI or HP proprietary?

[Michael Maurice]

I dont have another tape, I know the machine is HP but nothing else about it.

[paulsherwin]

If the drive is SCSI it will have a 50 pin connector, either a ribbon cable type simiar to an IDE disk connector, or a Centronics type similar to old parallel printer sockets.

A SCSI interface may allow you to substitute a slightly less ancient drive, depending on what it's used for. You could also connect it to a PC with a SCSI interface, which may give access to diagnostic info.

It's probably a proprietary interface though.

[Radio Wrangler]

I remember using the things, similar mechanisms were built into a generation of desktop calculators, all using the sme 3M cartridge. They were pretty reliable. If anything went wrong it seemed to be the cartridge. There is an endless belt which acts to drive/brake the spools. If things get out of kilter with loose loops of the actual tape, then you can get chewed tapes.

I had to take the screws out of a few and retension the tape to get it running again to avoid losing a wanted programme.

Expect a fault code and a sulking fit if the clock recovered from the data is off frequency while the capstan tacho is on its frequency.

Part of the design, ISTR, used the tach so that data could be read during start up acceleration and slowing down to stop.

David

[AC/HL]

This site implies that the tapes themselves are the main problem
http://hpmuseum.net/display_item.php?hw=257

[paulsherwin]

These drives are nearly 30 years old, and while they may have been reliable when new (60/120/150MB QIC drives did have a good reputation), if they've actually been in active use for all that time there are likely to be multiple marginal components, both mechanical and electrical.

[Radio Wrangler]

If a tape drive has lasted that long before failing, experiencing frequent use, then it's earned the word reliable. Even when young there was the occasional chewed tape, but Michael described fault codes without chew-ups.

I do know that the tacho-pulse disc on the capstan is to allow the reading electronics to track the immediate tape speed so the cartridge doesn't waste tape or time with acceleration/deceleration zones.

I'd guess that there is only a small group of tapes in use with that drive, so it's a question of whether the oxide's gone or whether the head's badly worn.

It ought to be possible to find the head signal amplifier and look for signals with a scope, similarly the tach pulses.

For anything HP, it's often worth searching the HP journal for articles which give a good description of the modus operandi, though it might be lumped in with any one of a number of desktop computers.

HP85A 9835A 9845A were around that period.

David