Some thoughts
On 8/4/2021 4:14 PM, Chuck Guzis via cctech wrote:
Whoever does it, I have a few suggestions when it comes to 40+ year old
tapes.
1) Bake the thing at 58C for a day or two. It might just prevent you
from staring at a tape stuck to the head and a pile of brown dust at the
bottom of the drive. (Before you start, make note of the brand and type
of tape; some are much worse than others). If you're uncertain, check
back here and I'll tell you what I know.
I have found that generally baking more than 12 hours has not made much
additional difference. I have been baking mine at 120F/50C.
2) If you're determined to use a SCSI drive, initially turn off
automatic retries (shoe-shining). With sticky tape, you can do a lot
of damage to the tape. Retries can come later when you're confident
about the condition of the tape.
Good idea. Also, if one notices it is sticking or squealing, STOP and
evaluate the situation before letting it go further.
3) Should the tape turn out to be sticky, don't try to clean it--it
will only foul up the cleaning equipment (I'm assuming a tape cleaning
machine here). Coat the tape with cyclomethicone. At least it won't
stick to anything and you'll get a chance to do a good read.
Folks are also doing that with floppies, though so few of my floppies
have stuck (and those that did didn't have anything that wasn't already
archived earlier file by file rather than image) that I haven't had to
resort to that.
4) If you have a choice of read speeds, use the lowest speed to start
with. Make sure that you can deal with tape errors.
5) Forget using a streamer--they're just not suited to dealing with
fragile tape.
My HP 88780B is a streamer, but also has a feed side tension arm. I
generally read good tapes end to end without any stopping. I have had
no problems with breaking or stretching tape - in the rare case where a
tape did stick badly to a head even after baking (1980's era tape or two
- they were just awful), the drive stopped immediately when it "overfed"
from the feed side which stopped the drive, just as a "standard" drive
(two tension arms or vacuum columns) would.
If you're not equipped to deal with this, don't attempt it. A tape
written 10 years ago, is not the same as one written 40-60 years ago.
The 1980s, in particular, were responsible for some truly wretched
stock. I thank my lucky stars that cellulose acetate never made it as
computer tape base. Curiously, tapes from the 1960s and 70s can be less
of a problem than those from the 80s and 90s.
That timeframe has been my experience as well (but I'd add that the
early to mid 1970's tapes have generally been no problem at all),
generally, but I don't think that is curious at all. It was a result of
the coatings used during those latter eras by some manufacturers.
Before that, those coatings were not used. Somewhere I kept a record of
which brands and series I found to be problematic, but I seem to have
lost track of it.
My .02 for what it's worth.
--Chuck
Also, before starting (after baking and cool-down) I unspool maybe 25
feet of tape onto a clean surface to make sure it isn't sticking. If it
does, I let it sit for a few hours, and then bake it again. Have not
had to bake for additional time very often, and in those cases, it ended
up not helping as much as one might like.
JRJ
