Screeching 5 1/4 FDD

From: Bill Dawson <whdawson_at_mlynk.com>
Date: Fri Oct 6 21:51:18 2000

-> 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.

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
Received on Fri Oct 06 2000 - 21:51:18 BST