5.25 floppies that read but don't write
Chuck Guzis
cclist at sydex.com
Thu Aug 20 23:46:41 CDT 2015
Re: Degaussing floppies.
Only part of degaussing a floppy is getting a strong enough degausser--I
use on made for wiping VHS carts--it gets very hot after only about 3
minutes of use and the thermal cutout belays my impatience until it
cools off. So it's definitely not wimpy.
However, to use it, you have to observe the correct mumbo-jumbo. You
press it against the floppy in question, hit and hold the power button
and *slowly* pull the disk away, moving said disk in a roughly circular
motion.
A quick check using Kyread shows no discernible magnetic pattern remaining.
On a related matter, I've found that using a very strong rare
earth/neodymium magnet (i.e. if you get your fingers between it and a
hunk of iron, you should not be surprised with broken bones or severe
tissue damage) on a "bad" high-density 3.5" floppy, followed by a pass
with the degausser will often return the floppy to usability. This
comes up occasionally when I'm asked to repair a factory-labeled floppy
that's developed issues. You want to keep the original labeling and
short of inserting a new "cookie", this approach actually works.
For what it's worth, I use the magnets with large steel ball bearings to
roll dents out of sheet brass--so I do have a valid reason for having
one around.
This goes to an observation that DSHD 3.5" media appears to develop some
sort of "fatigue" after a certain number of write passes.
For what little it's worth,
Chuck
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