Help w/ HP 88780 Tape Drive (corrected email).

Ali cctalk at
Thu Dec 3 12:05:11 CST 2015

*sorry a copy went out prematurely...

So I got my hands on an HP 88780 1/2" Tape Drive from list Member Mark
(Thanks!). The drive physically looks to be in good shape but was pretty
dirty when I got it. I've cleaned up the drive and powered it up. 

The good news: 

The drive powers up. Initially I had trouble getting it to load a tape but
that seems to have been resolved. The BOT, EOT sensors are good and the
basic drive mechanism (motor, eject, etc.) seem to be working.

The bad news:

Some of the front panel buttons are not working. Running test 72 shows
failure in the unload/rewind and online buttons. Luckily it seems to be a
mechanical problem. If I short the switch on the circuit board then the test
passes. The switches are mechanical push buttons that are soldered on so
should be easy to replace. Anyone know of a good or OEM equivalent
replacement? If need be I can get pictures of the buttons off the PCB.

The worse news:

The tape drive will not read/write. I ran test 01 which per the service
manual does a full general checkout of the drive. The test is a conglomerate
of other test routines. It fails when it tries to run test 177 (Buffer Write
Density ID). This is where I am currently stock and need advice on how to

Any help is appreciated. TIA


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