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#1
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"Tight" pancakes
In my continuing (futile?) efforts to diagnose performance problems
with carts, I decided to try varying the winding tension on the reel of a noticeably stiff late Audiopak to 1.) prevent jams, which had obviously taken place on this particular cart, a troublesome "double album" one) and see if there was a "rule of thumb" I could devise that would serve as a guideline for future repairs. Although this particular cart ("Yesshows"...no biggie) was operating when I got it and after installation of a Win-Gib® and the usual cleaning and application of PTFE, it was noticeably "stiff" when running the tape around manually, which I usually do by using a the eraser end of a pencil on the center of the casting. Tape "peel off" seemed stiff and begging for a hub jam, the #1 killer of cartridge tapes. I had removed the pancake and had cleaned the reel, something I do with most carts with a closed reel table, but it didn't help on this one. When I replaced the splice, I notice that taking up any further tension from the pancake would cause the tape to "squeal" a little bit...I could feel the "stiction" of the tape binding against itself as I took up more tension. Knowing everything was as pristine as possible, I decided to loosen the tension on the pancake by moving the outer edge clockwise (looking down on it) with a pencil eraser. After giving it about three turns, I again pulled on the end, and the squeal was gone. Pulling about to where the tape was originally caused it to start again. So, I back it back up another turn to where the squeal just went away, made the splice, and then ran up the slack, about another turn's worth. Now, when I ran the tape around manually, the tape, after redistributing the tension in the pancake, came out of the center hub almost effortlessly and there was far less drag on the guides, but no discernable slack while the tape was in motion. Slapping the cart back together, I popped it into the 8075 for a test listen...perfect! No more flutter, and the cart was nice and quiet, which is wasn't before. Out into the Paragoric car player, same thing...ran as well as the best of them. Thus, this is my new "rule of thumb" for tape tension...take up the slack on the pancake until it squeals, and then back off 2 or 3 turns on a ¼ mil tape (like most "double albums" and 90 minute carts) or maybe 1 turn on a ½ mil tape, as found in most 10-12 minute/track tapes and 45 minute blanks. Another technique I've adopted is no longer completely scraping and cleaning clumped up graphite off of the guides. It seems instinctive to me, after years of dealing with profession RTR machines, to clean the entire tape path before each serious usage, but I got to thinking that the graphite left behind is slicker than plastic, and should make the tape move more easily. Problem is, most times deposits of graphite and other back coating material is seldem if ever even; it usually is found on guides and hubs in clumps and is usually unevenly distributed on the guide. So now, I scrape off obvious clumps and uneven buildup while trying to leave the guide uniformly "black" in color. For most carts that have a mistracking problem, I've found without fail that the leading guide going to the contact block has crap built up on it, thus setting the tape up for a misaligned run across there and into the head guide. Cleaning that up always eliminates the problem. If the surface of deposited graphite appears to be flaking off of the guide in spots, I'll take a piece of burnishing cloth and try to evenly distribute it across the contact area of the guide. So far, this method has worked some wonders with "problem" carts, especially those which have a tendency not to track properly. It even tends to get rid of a lot of small flutter problems in carts prone to that, like later TC8s, which I've had speed headaches with from Day 1. I used to religiously remove any trace of graphite from everything inside the cart. No longer, but I do still scrupulously clean both the pinch roller and the reel hub, on which can usually be found lots of crumbs of back coating and dirt. Anyway, there's today's tech post! Enjoy. dB |
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#2
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Is there a way to fix a very tightly-wound (practically immobile,
crinkling up any tape pulled out from the center when forced to do so by hand) tape without completely unwinding the tape and winding it back on the spool again (that would be a nightmare) or using the solution presented by the 8-track FAQ, which (I believe) involves cutting the tape and splicing it together again? |
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