Bulk tape eraser

[Jerome H. Fine]

 >Chuck Guzis via cctalk wrote:

>>On 04/30/2017 07:38 AM, Mike Loewen via cctalk wrote:
>  
>
>>Looking for recommendations for a bulk tape eraser for SDLT and DLT 
>>IV tapes.
>>    
>>
>
>If it's just a small quantity to be erased, there are many Radio Shack
>videotape erasers being offered, some NIB, all for about $20.  I've used
>one for years on floppies and tapes.   It's not for erasing piles of
>tapes, as there's a thermal overload protector on it, limiting the
>amount of time that you can use it.
>
>--Chuck
>
I don't know if my experience with tapes for the TK50 / TK70 applies, 
but for
what it is worth, here is what was the problem.  When a tape has been 
written
by a TK50 drive, the TK70 drive will no longer be able to write on the tape
until the tape have been BULK erased.  Since I had a number of tapes written
by a TK50 and I wanted to use the tapes for producing backups using a TK70,
I obviously needed to be able to BULK erase those tapes.

FORTUNATELY, I had an old voice coil fram a speaker available.  It must have
been a large speaker because the coil was a cylinder about 3" in 
diameter and about
3" long.  The permanent magnet seems to have a few pounds of pull on any 
iron
object, so I thought it might be useful.  It probably takes about 30 
seconds of slowly
rotating the voice coil over the surface of the TK50 / TK70 tape to 
sufficiently
BULK erase the tape such that the TK70 drive would write on the tape.  
Since I
believe that the TK50 / TK70 tapes are early DLT tapes, this method may also
be successful, if a bit slow, for a small quantity of tapes.

Jerome Fine