[?] Bulk tape eraser - doesn't erase DAT tapes.

[David Chapman]

For security reasons I've been trying to use a Weircliffe BTE200 bulk
tape eraser to wipe a number of already recorded DAT tapes that I have
been given. Most of them are data tapes (Fuji DG4-150), and a few are
digital audio tapes (TDK Studio 124) - all of the same physical size and
appearance.

I've been following the instructions for the eraser, and it lights up
and 'buzzes' appropriately whenever the drawer is slid in, but the
recorded information on a tape is still there after an erase sequence,
and quite readable even after the tape has had several more passes
through the eraser. Unfortunately the company that made the eraser no
longer exists so I can't ask them for help.

I'm wondering if a possible reason for this might be that a digital
recording modulates the tape to such an high level that the magnetic
particles on it can no longer be randomly rearranged by the tape eraser.

I could, of course, put each tape back into the DAT recorder and
overwrite it with 'blank data' but this would take hours and hours in
view of the number of tapes that I have got, as well as causing a lot of
unnecessary wear to the recorder itself.

I don't know enough about this subject and wonder if anyone in this
NG can explain why the eraser 'doesn't'. I've got lots of these tapes -
does anyone (in the UK) need any if/once they have been properly erased?

ATB - Dave

 

[David Chapman]

That is a "standard" tape eraser that is made essentially only for
audio tapes - that is to say, only for tapes using low coercivity
ferrite.
DAT and other computer tapes use a high coercivity ferrite and take
about three times (or so) the AC magnetic field for effective erasure.
You need to use a BIG tape eraser, not a wimpy one hiding in a "big" box.

Ah! That explains it then. Many thanks for responding so clearly and
quickly. Now I must look around and try to find out where I can
hire/borrow a BIG tape eraser in the SE London area.

ATB, and thanks again - Dave