Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

shadoooo shadoooo at
Tue Mar 1 15:17:09 CST 2016

I have two TSZ07 here.
As they were sold as "for parts" obviously they both needed some repair.

One of the two had severe mechanical problems.
One motor had a loose unglued magnet inside, so there was a motor fault 
error, and the motor couldn't rotate freely,
making a rattle noise inside when operated by hand.
Of course it was better not to act on that before repair, to avoid to 
damage the magnet.
To repair it I needed to unscrew the reel (in my case the front reel 
with the loading mechanism to
hold the interchangeable reel with the tape), unscrew the motor from the 
frame, then remove the tacho (very delicate!)
and then finally open the motor.
The loose magnet appeared to be originally glued to the metal housing 
with cyanoacrilic glue, so I positioned it by hand
aligning it with the remaining glue traces on the housing, held it in 
place with a clamp tool then finally added new abundant glue all around, 
letting it to flow under the magnet. Then waited for 24 hours and 
The tacho wheel needed to be cleaned, as the very thin steel growth with 
some oxide in the small holes,
not being optically open enough to work.
You can see how this wheel is delicate... maximum care not to bend or 
crack it!

It worked!

PS= check very carefully your PSU, as both drives had severe problems on 
it, they are very prone to fail!
One simply ceased to operate after some time, and needed some component 
replacement to work again.
The second one did worst! It did fail beginning suddenly to put out 
pulsed voltage (8-10V peak) on the 5V.
I turned it off within a couple of seconds, but unluckly it fried some 
ICs on the digital board...
It had to change two Z80-serie ICs on the board, to let it finally work...
And of course to repair the PSU and test it for some hours with load 
before testing it again with the real hardware.


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