On Mon, May 12, 2014 at 6:01 AM, Bob Vines <bobvines00 at gmail.com> wrote:
Date: Sun, 11
May 2014 12:54:23 +0200
From: Marco Rauhut <marco at familie-rauhut.eu>
To: cctalk at
classiccmp.org
Subject: How to clean DEC Tapes
Hello all together...
i am restorating a DEC TU56 dual drive in the moment. My question is,
how to clean the tapes, not the drive.
The tapes i have are found in a garage, where they been for about 25
years without a case. Some ideas how to clean them without damaging?
Best regards
Marco
I forwarded your question to Charles Lasner and asked if he had any
recommendations. Here's his reply:
"This is pretty straight-forward. Tape on reel, reel not in cardboard
box or preferably cannister.
Tape is probably quite dusty, but should not have any other problems.
First wipe off the obvious surfaces carefully, not aggressively.
Then unfurl the first less than two feet and carefully clean by
placing within a small amount of cotton batting handplaced over the
top and bottom and gently pull away towards the end. That way, you
are exposing tape that will be totally clean other than the edges.
Then gently place the end onto a takeup reel and carefully wrap the
end gently around the hub until it obviously takes tension. [Note:
the takeup reel should COMPLETELY clean!]
Place some gauze and cotton over the head and then manually wind
forward the entire tape off of the reel.
Then completely clean the original reel, and inspect it for problems.
Some reels age badly and crack; it really depend not only on how well
handled, some plastic just will not last, while other batches will
apparently last indefinitely.
If need be replace it.
Assuming the tape has important contents, just wind it back to
original position now cleaned; expect a bit of oxide on the cotton
above the gauze. [The gauze is to protect the head and in case the
cotton slips off, hold it manualy with a free hand or perhaps it can
be stuck on with a bit of surgical tape on some of the edges. The
tape must be touching cotton and go smoothly on the tape movement both
ways.
If the pass onto the takeup reel shows a lot of dirt, of course
replace the cotton, etc.
If the tape is being recycled, consider reversing the tape completely.
This is a little tricky because you want the tape wound the other way
yet still oxide-side down. [It's easier to turn a DECtape into a
LINCtape and vice-versa!] But it can be done with some half-twist
tricks by using the most extreme reels on both drives and don't
involve either head. This has to be done manually because you are
trying to use two drives at once, etc. [Harder on a TU55 might need
some external winder unless they are arranged side-by-side, often that
is not the case.
In any case, you now have the former "inner" end on the outside and it
will likely have a pristine loose end.
And of course never cut anything off the tape. However, if it is
still there do cut off the 3M first 1 inch label. It can be sticky.
Some of the tapes didn't even have this label. In any case, the point
is we do NOT want it near the hub, but never cut off any actual tape!
Remember a format is you just make the tape loop on the takeup reel
and DO NOT WIND IT! Let the formatting program do the rest, don't
"help" it; it has extra-end-zone logic already, etc.
And if you do that right AND you happen to have a generous tape, you
are entitled to make a slight patch to the formatting program and
obtain a 3300 octal block long tape instead of the normal 2702 blocks
octal. With a one-word patch to OS/8 PIP you can get 857 free blocks
[records] instead of the normal 730 blocks [really records]."
Hope this helps!
Bob
Charles just reminded me that "One more thing: Restoring the TU56, is
he aware of the drive guides as a potentially serious issue [as in a
TAPE SHREDDER if it is not up to date!]?" An old. worn, poorly
maintained (over the years) TU56 drive will shred your DECtapes. One
big problen is that the different versions of tape guides wear from
the friction of the tape running over them and the "grooves" can shred
the tapes. They can cause the tape edges to curl up and down, causing
all kinds of serious problems, mostly making the tape unreadable, if
memory serves. DEC made several, mostly unsuccessful (I think), ECOs
in an attempt to solve this problem. One ECO made the problem worse.
All I can recall at the moment, without digging through archives, is
that part of a successful fix was to use a different spring which, I
think, put less pressure on the guides & tapes. Other parts of the
successful fix was to repair the working surfaces of both some of the
versions of the guides and some versions of the plate to which they
are attached.
My 2?,
Bob