DEGAUSSING FACTS

To erase recorded data, it is necessary for the strength of the degaussing field to be significantly greater in value than the coercivity of the magnetic media.

Data is typically not lost until its level has been decreased around 60% below its original 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.

By using AC current the degausser creates 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.

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.


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 Caution: Degaussing will render Media un-usable! See Note 1
TR-5, SLR40, SLR50, SLR60, SLR100 1650 Oe Caution: Degaussing will render Media un-usable! See Note 1
DLT tape III, DLT tape IIIXT 1540 Oe
DLT tape IV
1850 Oe
SuperDLT tape 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 Caution: Degaussing will render Media un-usable! See Note 1
Magstar: 3590, 3590-E 1600 Oe Caution: Degaussing will render Media un-usable! See Note 1
STK-9840, STK-T9940 1625 Oe Caution: Degaussing will render Media un-usable! See Note 1
LTO-Ultrium1 1850 Oe Caution: Degaussing will render Media un-usable! 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
5¼ 360 KB DD Minidisk 300 Oe
5¼ 1.2Mb HD Minidisk 650 Oe
VHS Standard & Betacam 700 Oe
SVHS 850 Oe
M II Betacam SP/Digital Betacam 1500 Oe
U-matic Video 750 Oe
Zip 100 MB Disk 1550 Oe Caution: Degaussing will render Media un-usable! See Note 1
Zip 250 MB Disk 2250 Oe Caution: Degaussing will render Media un-usable! See Note 1
SuperDisk 120MB 1500 Oe

NOTE 1

These products have 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.

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