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About Degaussing (Erasing)
Magnetic Media
 For more information or to Order: Click Here
or call 1-800-468-6888 for immediate assistance. |
An alternating current
(AC) bulk eraser (degausser) is used for complete erasure of
data and other signals on magnetic media. Degaussing is a
process where magnetic media is exposed to a powerful,
alternating magnetic field. Degaussing removes any
previously written data, leaving the media in a magnetically
randomized (blank) state.
The degausser must
subject the media to an alternating magnetic field of
sufficient intensity to saturate the media and then by
slowly withdrawing or reducing the field, the magnetic media
is left in a magnetically neutral state.
To erase recorded
data, it is necessary for the strength of the degaussing
field to be greater in value than the coercivity of the
magnetic media. Simply stated, coercivity is the magnetic
field strength, rated in oersteds (Oe), required to change
the magnetic orientation of the magnetic material. Check
with knowledgeable dealers or degausser manufacturers to
identify degausser models that meet your requirements.
Examples of typical coercivities for computer magnetic tapes
and disks are shown in table I.
Data is typically not
lost until its level has been decreased 65% to 75% (or more)
below its original saturation recording signal level,
dependent upon the drive system.
A complete erasure level, for most users, is considered to
be 60 dB below the original signal level – this of course
depends on user requirements. A 60 dB signal decrease
equates to reducing the signal to one tenth of one percent
of its original value.
Magnetic media
products that have factory prerecorded magnetic servo
patterns should not be degaussed. Degaussing would erase the
factory written magnetic servo signals and leave the media
unusable. For all other magnetic media (without magnetic
servo signals), after proper degaussing, the quality of
subsequent data recording should be unchanged or even
improved.
It is very important
to understand and follow the degausser’s operating
instructions. This is especially important for manual units
where the operator controls the media’s movement through the
degaussing field. For higher coercivity media, four passes
are often recommended – two passes, with a 90 degree
rotation for the second pass, and then repeat the process
with the media turned upside-down. Of course, these and
other important operating considerations will vary with the
type, power and construction of the individual degausser
models.
|
MAGNETIC TAPE PRODUCTS |
TYPICAL COERCIVITY |
COMMENTS |
| 9-Track
Reel-To-Reel Computer Tape |
300 Oe |
|
| TK50, TK70 |
350 Oe |
|
| 3480, 3490
OE |
520 Oe |
|
| SLR1, SLR2,
TR-1, DC2120, DC6150 |
550 Oe |
|
| SLR3, SLR4,
SLR5, TR-3, DC9100 |
900 Oe |
|
| SLR24,
SLR32, TR-4, ADR30, ADR50 |
900 Oe |
Do Not
Degauss, See Note 1 |
| TR-5,
SLR40, SLR50, SLR60, SLR100 |
1650 Oe |
Do Not
Degauss, See Note 1 |
| DLTtape
III, DLTtape IIIXT |
1540 Oe |
|
DLTtape IV
|
1850 Oe |
|
|
SuperDLTtape1 |
1900 Oe |
|
| D8: 8mm
112m, 8mm 160m |
1600 Oe |
|
| DDS1: 4mm
60m, 4mm 90m |
1590 Oe |
|
| DDS2 4mm
120m |
1750 Oe |
|
| DDS3 4mm
125m |
2250 Oe |
|
| DDS4 4mm
150m |
2350 Oe |
|
| DD-2 19mm |
1550 Oe |
|
| DD-2QD
(Quad Density) 19mm |
1850 Oe |
|
| DTF-1 |
1579 Oe |
|
| DTF-2 |
2300 Oe |
|
| Redwood
SD-3 |
1515 Oe |
|
| Magstar MP:
3570-B, 3570-C, 3570-C/XL |
1625 Oe |
Do Not
Degauss, See Note 1 |
| Magstar:
3590, 3590-E |
1600 Oe |
Do Not
Degauss, See Note 2 |
| STK-9840,
STK-T9940 |
1625 Oe |
Do Not
Degauss, See Note 1 |
|
LTO-Ultrium1 |
1850 Oe |
Do Not
Degauss, See Note 1 |
| Mammoth
8mm, AIT-1 8mm, VXA-1 8mm |
1320 Oe |
|
| AIT-2 8mm |
1380 Oe |
|
| M2 Mammoth2
8mm |
1350 Oe |
|
| 3.5" 720KB
DD Microdisk |
650 Oe |
|
| 3.5" 1.44MB
HD Microdisk |
720 Oe |
|
| 5 _ 360 KB
DD Minidisk |
300 Oe |
|
| 5 _ 1.2Mb
HD Minidisk |
650 Oe |
|
| Zip 100 MB
Disk |
1550 Oe |
Do Not
Degauss, See Note 1 |
| Zip 250 MB
Disk |
2250 Oe |
Do Not
Degauss, See Note 1 |
| SuperDisk
120MB |
1500 Oe |
|
| NOTE 1: DO NOT DEGAUSS |
| This product has factory prerecorded magnetic
servo tracks. The media will be unusable, if the servo tracks are bulk
erased (degaussed). Products that use factory prerecorded magnetic servo
signals should not be degaussed unless destruction of the recording
media is desired. |
| NOTE 2: DO NOT DEGAUSS |
| This product has factory prerecorded magnetic
servo tracks. But Peripheral can degauss, test, and remanufacture them
for you. |
Please call us for more information or a quote
(800) 468-6888,
email us at periphman@periphman.com ,
or fax us at (303) 371-8643.
You can also fill in the Information Request Form here .
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