Roman Black wrote:
>
> John La Rooy wrote:
> >

> >
> > ANY tape???
> > we were trying to erase some DLTs just before christmas
> > the MRI machine didn't work, neither did the induction furnace
> > we were trying to remove the formatting from the tapes :o)
> >
> > john
>
> Wow!! Firstly, whats a DLT? And secondly it amazes me that
> you couldn't demagnetise a tape with a strong AC field.
> My bulk tape eraser is a lot stronger than the degauss wands
> we use on TV's. Some TVs have a metal frame that slowly gets
> magnetised by the earth's field over many years. These are
> hard to degauss. I use my bulk tape eraser, which always
> works although it might take a lot of minutes. That's
> annoying because of its low duty cycle.
>
> Surely a strong AC magnetic field WILL demagnetise
> anything if given enough time?? Hmm...
> -Roman

DLT=digital linear tape. the ones we had were 20 or 40 Gigabyte i think
we upgraded our tape drives only to find that they worked fine with new
tapes
but not the $10,000 worth of tapes we used in the old drive. the
manufacturer
advised us to bulk erase the tapes. the MRI machine wiped the tapes
enough
to make the data on them unreadable, but not enough to work with the new
drive.
We finally had to send them to singapore to get them erased.

at a guess i'd say the tapes do have magnetic shielding built in

john

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