Subject: Re: TK50/TK70 tapes
To: None <>
From: emanuel stiebler <>
List: port-vax
Date: 06/22/1999 06:44:51
-----Original Message-----
From: Stan Pietkiewicz <>
To: port-vax <>
Date: Monday, June 21, 1999 9:37 PM
Subject: TK50/TK70 tapes

>While trying to use a  TK50 tape in my MV3600's TK70 drive, the drive
>went into read-only mode, and tar complained that it couldn't write to
>the tape. This happened on a number of tapes, even though I eventually
>found one that I could write to.
>Is this happening because the tape was previously written on a TK50
>drive??  If so, can the timing track be erased with a powerful permanent
>magnet (and from which side?) or is an alternating magnetic field
>needed? I'm asking about the permanent magnet because the audio/video
>equipment dealers I've talked to don't stock a *good* bulk tape


I guess, there should be slowly a TK50/TK70 FAQ ;-))

The world, how it should be:

1.) A TK70 drive works on a TQK70 controller, writes/reads TK70 tapes, TK50
tapes are read only.

2. A TK50 drive works on TQK50/TQK70 controller, writes/reads TK50 tapes.

Some remarks to the "world" above:

a.) Sometimes, some people like to play with magnets/bulk erasers. So you
can get TK50 tapes that are formatted as TK70, and vice versa. You should
erase them and use as intended. Means a TK50 as TK50, TK70 as TK70.

b.) The TK50 tapes are also known as CompacTape (COPMAC WITH TWO 'C' !!!)
The TK70 are known as CompacTape II.

c.) If you want to push your luck ;-))

It is possible to use a TK50 tape in a TK70 drive, after formating the tape
on a TK70.

BUT: (It should be taken seriously !!!)

THIS IS NOT SPECIFIED !!! The TK50 and TK70 tape material is different, and
the write current of the TK70 drive is different (IIRC, lower)

Once again, this is for playing/temporary storage only, or for BACKUPs, you
never need again ;-))

But it works, and nobody knows why. (Magic ?)

d.) What you need for erasing a tape. A $1000 bulk eraser, or a $0.20

If you can operate your drive outside the computer, remove the metal cover
of the drive, and put the magnet near the tape while the drive try to feed
the tape in.


If you can't operate the drive open, use the bulk eraser ;-))

e.) If you can choose between a TQK50 or TQK70 controller for the TK50
drive, take the TQK70. It's faster.

f.) If you have problems with your TK50/TK70 drive:

Clean it !!!
I have no real/good explanation for this, but the TK50/TK70 drives are
better dust/dirt magnets as most of the vaccum cleaner I know. So most of
the problems you usually can get with a TK50/TK70 are due to dirt/dust on
the tacho/LEDs inside the drive.

HOWTO: If the drive is dirty, open the metal cover nothing more !
and clean it carefully. There should be 4 LEDs, which should be made clean,
and the area around. And, because you opened the drive already: there is
this "Take Up Leader" to feed the tape in. Check it too, if it is bend, or
If you have to replace it, the DEC-PART-NUMBER is 74-28268.

That's for the moment, if there is something wrong here, sorry.
This was written in the morning, and after the first cup of coffee ;-))

Hope it helps,