TK50 cleaning and unloading issues, new thought:

Chris Zach cz at
Sat May 23 11:16:52 CDT 2020

With the 11/83 running pretty well I decided it was time to derack it 
and try putting in a TK50 tape drive. I have two and a TQK70 controller 
(which should work with a TK50) so I popped it in and started to test.

On the first unit the tape was already loaded and "stuck". Cleaned the 
head by lifting it up, cleaning with isopropyl alcohol on clean no-lint 
swabs and it unloaded properly. Now loads and unloads with no issues on 
two tapes.

Second unit was a bit more interesting, even with a clean head it would 
not unload. It would spin the tape, get to the point where the leader 
was on the way through the head system then it would blink endlessly. 
Took it out and moved the tape with a screwdriver through the hole and 
found the problem:

The leader tongue had bent backwards a bit and as a result it was 
getting caught in the head slot when rewinding. The TK50 controller must 
be smart enough to detect the increased torque and stopped before 
ripping the tongue through. I took it off, bent it back to straight, put 
it in and now the tape loads and unloads properly.

I wonder if later model LTO tape units have the same tongue and leader 
and can be swapped into a TK50.

Another question: Under RT11 what device is a TK50? Is it MQ or 
something else? And is there a utility to allow a TK50 to be written 
from a SIMh image to real tape like PDP11GUI?


More information about the cctalk mailing list