[Info-vax] DLT Tape degaussing services

[Rich Jordan]

On Mar 18, 5:35 pm, Chris Scheers <ch... at applied-synergy.com> wrote:
> Rich Jordan wrote:
> > On Mar 13, 5:34 pm, John Santos <j... at egh.com> wrote:
> >> In article <gpeblu$cj... at naig.caltech.edu>, g... at ugcs.caltech.edu
> >> says...>
>
> >>> Richard B. Gilbert <rgilber... at comcast.net> wrote:
> >>>> Simply degaussing DLT tapes is not a good idea.  They have some sort of
> >>>> "formatting" or a "clock track" that is necessary for proper operation.
> >>>> Once degaussed, they may never work again.
> >>> As I understand it, that isn't true for DLT.  
> >>> (Or at least not the current versions of DLT.)
> >>> It is for Ultrium (LTO) and some others, though, so one
> >>> should be careful before degaussing a new tape system.
> >>> Also, in some cases degaussing is required.  DLT1 uses the
> >>> same tapes as a DLT IV, but the magnetic signal is different.
> >>> A signal left from the older drive will not get fully erased,
> >>> and will interfere with the new data signal.  
> >>> According to wikipedia, the DLT formats that do use a
> >>> servo track use an optical track on the back of the tape.
> >>> -- glen
> >> Many years ago, I got a degausser at Radio Shack for less
> >> then $20 IIRC.  It is *not* a static magnetic field; it uses
> >> A/C current to generate a 60Hz (probably 50Hz would work
> >> just as well) varying magnetic field, and you had to move
> >> it slowly around the tape, not just hold it in one place.
>
> >> It worked great for 9-track open reel tapes, and for TK50s
> >> and TK70s (DLT versions -1 and 0, I think, based on the
> >> current numbering scheme.)  People used to occasionally
> >> try to write to a TK50 in a TK70 drive, which would muck
> >> them up, or write to a TK70 in a TK50 drive, which would
> >> work fine, but render the cartridge unwritable in a TK70
> >> drive.  (Bad because you couldn't tell by looking at it
> >> this had been done and TK70's cost about 2-3 times as
> >> much as TK50's at the time.)  Degaussing usually fixed
> >> both these conditions.
>
> >> No idea if it would work with a DLT IV tape or not,
> >> but it sounds like a cheap enough experiment to try.
>
> >> --
> >> John Santos
> >> Evans Griffiths & Hart, Inc.
>
> > John,
> >      unfortunately Radio Shack tells me they no longer carry those.  I
> > haven't seen one on ebay this past week either (there are a couple of
> > others though).  Without knowing the 'oersted rating' there's no way
> > to know if one of those would be powerful enough; the manual warns
> > that hand held tape degaussers may not be strong enough to do the job.
>
> The Radio Shack unit I have is part number 44-233.  You might see if the
> store can track it down under that number.  I don't find any
> specifications on the box or manual.
>
> I've used it successfully to degauss TK50 tapes written in TK70 drives
> and TK52 tapes (TK70) written in TK50 drives so that they could be used
> in the "correct" drives.
>
> It is also good for degaussing DAT tapes.
>
> I've also done some DLT IIIs and DLT IVs.  Degaussing DLT IVs for use in
> a Benchmark VS80 had mixed success, but it is not clear if the problems
> were with the degaussing or if the problems were with the Benchmark drive.
>
> --
> -----------------------------------------------------------------------
> Chris Scheers, Applied Synergy, Inc.
>
> Voice: 817-237-3360            Internet: ch... at applied-synergy.com
>    Fax: 817-237-3074

The (HP) VS80 drive we're looking at definitely doesn't like the
lightly degaussed tapes I was able to get tested.  That was just using
(large, heavy) disk drive magnets though, not a real degausser.

The Radio Shack units are no longer available from RS.  However I see
I made the wrong guess on fleabay.  Degausser doesn't bring up much.
"Tape Eraser" brings up a lot more, and some at better prices.  Maybe
I'll pick one up to try.