info-mac@uw-beaver (02/02/85)
From: Steven B. Munson <sbm@Purdue.ARPA>
OK, I have 14 responses to my survey, and I don't seem to be
getting any more, so it looks like it is time to figure out what the
results mean. I was a little surprised to find that no one that
replied had ever cleaned the disk heads, and most didn't know it was
even possible. Here is the data:
Age of Number that Number that didn't
Macintosh found scratches find scratches
? 2 0
1 mo. 1 1
3 mo. 2 0
7 mo. 0 1
8 mo. 1 0
9 mo. 0 3
10 mo. 0 1
12 mo. 1 1
Total 7 7
Surprised? I sure am. The randomness of these results seems to
indicate that cleaning the heads has nothing to do with scratches on
the disks, although it would have been nice to have a group of people
who clean their heads to compare this to. After thinking about it, I
have a hard time believing that the heads can get so gritty that they
will scratch the heads as a result of normal use. My understanding of
magnetic pick-up heads is that, when they get dirty, they simply don't
pick up the signal as efficiently, not that they scratch the medium.
An interesting note is that two of the people that didn't have
scratches asked me what kind of disks I use, saying that they used the
Apple 3.5" disks *exclusively*. Most of my disks are Maxell, but the
ones I use most are the ones that came from Apple with MacWrite and
MacTerminal. I have examined all my disks, and found that only the
Apple disks are scratched! The surface of the Maxell disks is not as
smooth and shiny as that of the Apple disks, though, and may not show
scratches as easily.
One note mentioned that the scratches could be caused by the head
digging into the disk when it is loaded, and that it might be a
defective drive. I don't feel very comfortable with the idea that half
of the Macintoshes out there have defective drives, though, and the
person who first noticed the scratches had this reply:
One person has written to say he thinks it may be damage being done
when the head gets loaded onto the disk, if these drives have head
load/unload. I don't know if they have that (you can't hear it, if
they do, whereas most drives I've seen make a distinct noise when
the head loads and unloads).
If anyone knows whether the Sony drive loads/unloads the head, it might
be useful information for the rest of us. I am still unsure about what
causes the scratches, but I am not as worried about them as before.
Since one of the disks I use fairly often (it has ResEdit on it) is a
Maxell disk and shows no signs of damage whatsoever, the problem seems
to be related to my Apple disks more than to my drive. I can't explain
why other people using Apple disks do not have this problem, but we
obviously need more information to pin it down.
One way or the other, though, there is now a lot of interest in
head cleaning, so the rest of this message is a summary of my knowledge
of head cleaners for the Macintosh. The dealer I got my Mac from
(General Micro) says that the heads should probably be cleaned every 20
hours; that's 20 hours that the disk turns, not 20 hours of Macintosh
use. ComputerLand doesn't know anything about head cleaners for the
Macintosh. The maker of the head cleaner I bought says they should be
cleaned every week, which probably works out to 20 hours of disk time if
you use the Mac a lot. According to John Roach@RUTGERS, a Macworld
article recommended about once a month, and the manufacturer of his disk
cleaner recommended about twice a month. He went on to say,
Some people have even suggested that cleaning was detrimental to
the heads and warned against ever doing it.
This suggestion always comes up in a discussion of whether to
clean/demagnetize heads or not. I have been cleaning the heads on my
tape deck for years (I can hear the difference when the heads are really
dirty), and I have noticed nothing but improvement. However, I don't
claim to be an expert on magnetic pick-up heads, especially in
computers.
The method for cleaning the heads on a floppy drive is to take an
empty case the size and shape of a diskette, put a cloth disk with
cleaning solution into it, and stick the cleaning diskette into the
drive. I know of two head cleaning systems -- one called Floppiclene by
Automation Facilities Corp. (the one I bought), and the other called
Macintosh 3.5" Head Cleaning Kit (I guess they hadn't given it a name
yet when I saw it advertised) by Nortronics Co., Inc. They both come
with the re-useable diskette jacket, cleaning diskettes, and cleaning
fluid in a spray can.
Floppiclene costs $25 and comes with 10 cleaning diskettes and an
alcohol-based spray (I think). It also comes with special cloths for
cleaning the screen of the Macintosh. The head-cleaning procedure is to
spray half of the cleaning diskette with cleaning fluid, turn on the
Macintosh, insert the cleaning diskette, and let the Mac try to boot
from it. It will spin for a few seconds and spit the diskette back out.
You keep pushing it back in until it has spun for about 30 seconds.
Then you throw away the cleaning diskette. Each diskette is good for
one cleaning. A refill is available with 25 cleaning diskettes for $13.
The Nortronics cleaner costs about $40, according to the winter
1984 issue of "The Macintosh Buyer's Guide", and comes with 2 cleaning
diskettes, a freon-based spray, and software that tells the user what
to do, moves the head to a clean part of the diskette for subsequent
cleanings, and tells the user when to throw the cleaning diskette away.
The cleaning diskettes with this system are re-useable; I don't know
how many times. I don't know anything about the refills for this
system.
I don't think freon has any advantage over alcohol for cleaning
heads. When you clean an audio deck, it is better to use freon on the
pinch roller, because alcohol will dry out the rubber, but I don't
think there are any rubber parts in the Sony disk drive; anyone know
for sure?
My conclusion is that, although dirty heads *may* never cause any
harm, it is a good idea to clean the heads every once in a while.
Twice a month sounds pretty safe to me.
Steve Munson
sbm@purdue
Fine print:
These opinions are entirely my own. I have no affiliation with any
company, no employer, and I don't even know anyone that entirely shares
my opinions.
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From: Steven B. Munson <sbm@Purdue.ARPA>
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To: Hans.Moravec@CMU-RI-ROVER.ARPA
Cc: info-mac@Purdue.ARPA
Subject: Re: Dirty disks?
In-Reply-To: Your message of 31 Jan 85 05:08:41 EST.
<8502011954.AA27067>
Thank you for clearing up the confusion. The revelation that the
data is stored on the bottom surface of the disk, of course, makes the
extensive article I posted the morning before you sent the note look
really stupid, but it takes a real load off my mind.
Steve Munson
sbm@purdue
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Date: Thu, 31 Jan 85 17:41:35 pst
Subject: Re: Cleaning disk heads
Newsgroups: fa.info-mac
In-Reply-To: <645@uw-beaver>
Organization: Fortune Systems, Redwood City, CA
You'll have to pardon me if this is a little disjointed, there are a lot
of factors that interact to cause problems resulting in media damage.
Although the surfaces of diskettes are burnished by the manufacturer,
your disk drive finishes the task. Better diskettes mean less head
wear and less build up on the heads. Disk drives which are used
exclusively for copying new diskettes wear out much faster than drives
under normal use.
Diskettes vary not only from vendor to vendor, but also from batch to
batch so it is difficult to generalize. However, some vendors have
better burnishing equipment and therefore a better media surface.
If you have been using a diskette for a while and examine the surface,
you can sometines see shiny spots where the heads have polished the
surface. The spots sometimes show gross coating defects: splatter,
runs, or drops. In most cases you won't notice a problem because the
defects are not serious enough to affect the head to media contact or
the discontinuities are not large enough to cause significant bit
(flux) movement. Remember, bits are never written in exactly the
same place due to the speed variations in disk rotation so a small
defect may cause intermittant failures. If you trust your diagnostic,
you should toss diskettes with any failures, if you are rich, or any
repeatable failures, if you are poor.
Anyway, back to the main track. The use of lower quality diskettes
require more frequent head cleaning. However, some floppy drive head
cleaning kits, like some VCR head cleaning kits, are too abrasive to
be used regularly. Which ones you ask? I can't tell you, but there are
two rules of thumb: 1) never use a cleaning kit that has not been
recommended by the drive manufacturer unless you are willing to go it
alone and 2) generally the best kits come from the most reputable
vendors. I know for a fact that large companies like Verbatim and
Dysan spend a lot of time consulting with major floppy drive vendors
before releasing their head cleaning products. Sort of "don't bite
the hand that feeds you".
All of the foregoing assumes that the drive was designed, manufactured
and adjusted correctly. The act of loading the heads onto the diskette
surface can cause damage if the drive or heads are not correct...like
catching an edge on a ski.
Dan Jones
UUCP: {ihnp4,ucbvax!amd70,hpda,sri-unix,harpo}!fortune!jones
DDD: (415)595-8444 x 440
USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065