-> On Thu, 5 Oct 2000, Lawrence Walker wrote:
->
-> > I have a hard to replace dsdd floppy disk that produced a
-> > screeching noise while attempting to read it on a win98 box under
-> > Dos using a Dos program.
The screeching is caused by lack of lubricant on the disk surfaces.
The drag caused by this will sometimes slow the disk rotation enough
to cause errors, even though enough of the original disk surface
remains to allow reading.
-> >I quickly removed it and tried to read it
-> > on another Dos box also with a HDFDD. No screech but only the ->
directory was readable, not the contents. I
checked the original ->
FDD again using a scrap dsdd floppy and had no trouble with it. -> >
Anyone
have any thoughts as to what would have caused this ? -> ->
Whenever I have heard that horrid squeal, it has been followed with
the -> disappearance of the magnetic media on a track or cylinder.
Whenever I've had this problem occur it has been caused by improper
storage of the subject disk, usually in an area of high humidity and
warm temperature. When the disk surface shows a white
splotching/spotting, lighter brown splotching or other discernible
discoloration, it is caused by a mold or fungus that eats away the
lubrication from the disk surface. This splotching can cover large
areas and be very noticeable or it may be hard to discern. It may
cover the entire surface of the disk, or it might only be seen in the
head slots. If the rotational position of the disk has not been
disturbed since its removal from storage, rotate it 1/2 the width of
the head slot and look for a difference in coloration on the magnetic
surfaces.
There does seem to be a slight discoloration in spots. What was
the original lubrication comprised of. Was it just something
naturally occuring in the oxide ?
I've come up with a solution (no pun intended)
that will usually allow
the data to be recovered if the disk isn't too badly damaged, like Don
mentions (above). This procedure also applies to 3.5" disks. Examine
the surface of the floppy before you put it in a drive for the first
time, especially if it has been stored in a humid, warm area or if you
don't know where it has been stored. Look for the splotching. If it
is present, then be ready to immediately make a copy the first time
you insert the floppy into a drive. You may only have this one chance.
Apply some 91% (non-scented) or preferably 99% Isopropyl Alcohol to
both sides of the disk in the head slot area. You want the alcohol to
be absorbed onto the anti-friction liner of the floppy jacket, and you
want enough of it so that it lasts through the reading/copying
process. It may help to pucker the jacket to aid in the absorption of
the fluid. Rotate the disk inside of the jacket enough that you are
sure it is thoroughly wetted. Don't wet it so much that fluid is
dripping off, though. If it is, shake off the excess, head slots away
from you. The dripping and slinging of alcohol inside the disk drive
mechanism is not good for the lubricated parts inside nor for the
powered up electronics. INSURE EVERYTHING IS READY TO READ/COPY. Now,
insert floppy and quickly perform the read/copy. I highly recommended
that you have two floppy drives for doing this, unless you can read or
copy the diskette in one pass. If not, you may have to wet the floppy
more than once.
If you get errors while reading, (S)kip or (I)gnore them if (R)etry
doesn't work on the first couple of retries. The alcohol evaporates
quickly, and you risk destroying areas of the disk that may have been
readable had the alcohol remained.
The alcohol accomplishes several things. It acts as a replacement for
the missing lubrication, it helps scrub the fungus residue from the
disk surface (which ends up on the jacket liner), it protects the
heads from the abrasion of the molded areas and it keeps the heads
flushed during the data recovery process. Due to the lubrication, the
diskette will also rotate at the proper speed and timing/sync caused
errors are eliminated.
Alcohol is fairly inert in respect to the plastics used in many floppy
drives. Also, if the drive used in this process is single sided,
alcohol will not weaken the adhesive commonly used to attach the
pressure pad.
I've found that the best type of floppy storage for preventing this
lubricant eating fungus, other than a proper storage environment, is
an airtight container. Ziplock type bags work well.
Bill
whdawson
Thanks Bill. This is just what I was looking for.
I have an old Xerox 51/4 cleaning kit with spare cleaning disk
issues which uses isopropyl. Perhaps using that first on the fdd will
clean the heads and also leave a little on the heads for better
lubrication. I'll also use a little on the disk itself as you suggest.
This set was one that I acquired recently, so I don't know under
what conditions it was stored. Seems like I'll have to check some
of my older disks as well even tho my place is not especially hot or
humid. I have seen splotches occasionally on disks but just
considered it water or alcohol residue like you often have on old
audio records.
Great info, the cc m-l comes through again.
ciao larry
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