New subject: Ultrix 2.2 was: (Re: Ya know, I really dislike TK50 drives...)

14 Apr 2001

...
 > What did you in are the sensors on the 2 tape
rollers.  If either of the
> rollers stick in either direction the drive decides it does not know where
...
 > on the tape it is and shuts down.  I use a marker
on the top of the rollers
...

I assume these are the 2 rollers, about 1" in diameter, either side of
the head assembly. 
Correct.

...

I've pulled a TK50 to bits (non-destructively), and the front roller
doesn't seen to have a sensor on it. It does appear to have a height
adjustment, which would not be the thing to twiddle.

The rear roller has a slotted disk + optoswitch at the bottom end. I
assume this is the sensor you are refering to. 
Yes but I am sure the front one has a sensor also since the slightest
heasitation there also shuts it down.
I have not taken the time to find a front sensor but it must have one.

...

> to determine which roller is causing the problem.  Then just watch the marks
...
   while loading
a tape.

 Don't feel bad - I have gone through over a dozen drives to get good ones
 and the biggest cause failure are those roller bearings. 
Is it possible to replace the bearings? I've not attempted to dismantle
the senosr (yet!), but it looks possible. Of course after doing that
you'd probably had to do a tape path and head alignment (which could be
'interesting')... 

The rear one is not bad but the front one does involve some alignment.
Again I have not taken the time.  I did try lubricating the top bearings
with a syringe and still had problems.  I then removed it and did the bottom
bearing.  It ran free then but I had alignment problems and no alignment
tape or info.  At that point even with over a dozen drives on the way to
scrap metal it was not worth any more time to me.

Dan