What causes cassette tapes to get "eaten"?

Hi guys. I actually cleaned the capstains with isopro alcohol and the qtips. I don't think that is the problem. I removed the plate to see what is going on after pushing play and indeed, at some point the tape does not roll well. But again, the problem is random and always with long tapes (90 minutes or 100 minutes). Strange. Another question: is it logical to clean the pinch rollers with isoprop alcohol?
 
Man...i just google The Walking Head for 1 minute until i got the joke. :)
I will clean and re-clean and no dirt gets on the qtip.
 
Hi Guys,

I did the cleaning process. I was reading about a special cassette called "Mirrorring Cassete". I read, also, you could fabricate that tape too, by breaking a normal cassette in certain parts. The question is, what exactly should i watch on the cassette?
I notice that the "eating process", is like "pinching" the tape but in a diagonal way. There is a weird sound, in which the tape gets eaten and then, after pushing Stop, there is a this diagonal line.
 
Putting the tapes back in the box and keeping the machine clean inside has always prevented that problem. Just Q-tips and alcohol....
 
Hello everyone,
I apologize in advance for the lengthy post. I know this thread is old but I have a very relevant question, that I was wondering if you can help me out with. I found an old top loading cassette recorder from the 70's. It's a radio shack / realistic. Well built, got it for voice recording. Anyway, I have some experience with replacing belts and idler wheels on cassette decks, lubing etc... But when I started testing this particular recorder, it had some issues. I will explain these briefly and also have posted a couple of photos of the inside mechanism. I am asking for your help in identifying the issue.
First of all, the recorder is the Realistic CTR-34. Looks very low use. Before opening her up I tested the functions. Here were the results: Rewind = OK. Forward = OK. Play = pinch roller / capstan engages and pulls tape through but left take up spool doesn't turn, tape spills. I opened 'er up, examined the belts, one was a bit loose, so I changed both (with temporary use of rubber bands to verify function). I rechecked function again. Forward and Rewind are very strong but the left take up spool doesn't spin at all (when in play). I then opened the top to view the idler wheels and the rest of the mechanism. (Photos attached).
The pinch roller looks fine, grips well. The capstan spins strong. The heads and tape path look fine. The idler wheels rubber is totally fine, grips well when in rewind and forward. When I press forward or rewind, the idler wheel mechanism either go to the the left or right, which in turn, turns the spools (verified by hand, the spools present with lots of torque). All fine here. When I press play (as seen in photo), the mechanism slides up (which disengages the idler mechanism). I deducted that the idler wheels' only function is to rewind or forward. The play function (take up of tape by left spool) must be controlled by something else. But what?? Are there any belts or additional idlers that are missing there? And where do they go? Can you see anything that I don't see?
From my own visual inspection, the only things which provide any direct movement are the idler wheels (for REW and FF) and capstan (for controlling tape) and the rest are passive. But what controls the left take up spool (when in play)? (Please click on each image for enlarged view).
Thanks in advance for looking and for your help.
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You had me confused by the "left spool doesn't turn-spills tape", but I see by the orientation of your photos, you mean the take up spool.

I would fool whatever sensors that detect that a tape is inserted, and enter play mode. The take up spool should turn. Examine which idler turns-it appears that the idler nearer the supply side, turns the idler nearest the take up side. Do both turn? If not, then the idler rubber is likely needing replacement. If both turn, but the take up spindle does not, then turn the spindle by hand to see if it's binding. Binding can be caused by old lubricant or lack of lubricant in the spindle assembly (more likely), or by a brake lever that is not moving out of the way during play (less likely).

Another possibility is that the idler nearest the take up is not moving into position to engage the take up spindle-again, something binding in the mechanism preventing it moving into position.

Keep in mind that rubber bands might not allow for proper transfer of motion of the idler. It might be slipping-you would need to look at the transport from below, to see if the pulley slows with play engaged.
 
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Hi, thanks so much for looking into my post. The spools turn smooth and easy by hand. There is no sensor, this thing is purely mechanical. Yes I meant the take up spool not turning, not taking up the tape and spilling at the capstan. And this is where the mystery deepens. There is nothing underneath which spins or controls the spools (R and L). The spools are mounted to the metal chassis, are completely passive. Except the idler wheels moving them only for forward or reverse- both work strong and fine. Do you see that little white vertical plastic shaft in front of the recording / play head (in photo 1 and 2) and that metal fork which slides onto it (in the 2nd photo)? Well, when reverse or forward are engaged that metal "fork" slides that white shaft to the left or to the right, which moves the idler system to the left or to the right, which then moves the spools. But in PLAY (photo 2), do you see how that metal "fork" slides forward (and prevents the white vertical shaft from moving sideways)? This prevents the idler system from moving and remains neutral (doesn't go left or right). This is intentional from that design. I am certain the idler system does not assist in any way in PLAY or in moving the take up spool. That's why I'm wondering if there is any belt or idler that looks to be missing from the mechanism (which operates the take up spool in play). I checked everything, makes no sense. Do you see that seemingly empty white round spool between the capstan shaft and the larger black supply spool? Looks like a place for a belt or idler but problem is that it's also passive, nothing under it powering it. Like I said that this thing is a total mystery. Do you think it would be better and would it be allowed for me to post this question again (with the photos) as a separate new post / topic, perhaps more people will chime in?
 
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UPDATE: Someone just pointed me to a thread elsewhere (same exact issue):
http://www.tapeheads.net/showthread.php?t=63017
This confirms that a belt (or some kind of ribbon or string) is indeed missing from that area but what a strange mechanism design. Never saw that before! I hope a temporary rubber band brings back functionality, at least for testing. Weird design. And I still don't understand how it's supposed to "take up" tape. I'll try it though.
 
There appears to clearly be a belt missing (easily seen on the first two pictures) that routes around the take up reel, the capstan and an idler. I have never worked on one lime this, so appears it is unusual because it is a cheap design that requires a single motor to do everything. So possibly the supply reel is actually a brake that regulates the tape feed to the capstan while the capstan drives the take up. In order for the capstan to drive the take up reel, then it must always turn faster than the capstan & supply to prevent tape build up. This is an incredibly imperfect system because the tape pack size is completely different from beginning to end, so capstan speed would have to be all over the place from beginning to end. Hopefully this is not how it works, or tapes made on this unit could only be played back on it. Similarly, prerecorded tapes would be fast in the beginning and slow at the end.
 
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Interesting way of doing it. The single motor setups I've seen did all this from the back side using a clutch underneath the takeup and rewind reels, and usually an idler or a gear that would swing in to bypass the clutch in fast forward and reverse. I'm guessing this one has the clutch as part of the large takeup reel, or maybe its in the intermediate pulley. There has to be a way of allowing for variable takeup wheel speed though. The amount of tape pulled in by one turn of an empty wheel vs a full wheel is considerable. The speed of the tape past the head is constant based on the capstan and pinch roller.

fast forward/reverse has to be on that moving idler in the center. Swing one way and it winds back the supply reel, swing the other and it runs the takeup reel through that second idler wheel to make it spin the other way.


to answer the original post, most of the time when I've had tapes get eaten, the takeup wheel isn't going and usually its been a belt problem. At this point in time gummy lube and failed plastic mechanism parts can't be ruled out in the deck, and problems with the cassette itself are also not off the table.
 
Back when, during the cassette machine craze there were only two dependable producers of cassettes. Maxell and TDK. From the 70's until I got rid of all tape in 2019, there were only two Maxell cassettes that every failed me. It didn't matter if I were using my Nakamchi 550, 581Z, 682, or my Sony car stereos, or Ford, Dodge Ram, Mercury, Chevrolet, Oldsmobile or Buicks, Hondas or Acura players. Every other tape failed all the time. We sold. Sony, BASF, Ampex, TDK, Maxell, Scotch, etc over the years and only the Maxell's and TDK's performed as I thought they should. I mean if they can hold up in cheap car factory players they can perform in anything. That said I never used C-120's only C-60's and 90's. Also mostly Chrome and metal tapes after they came on the market. I never used C-46 either.
 
This thread brought back memories (of frustration) --- I thought I would weigh in on a completely different experience of decks munching tapes...

Back in high school I bought myself a Pioneer CT-F2121. It was a beautifully built deck and with a minimum of features and did everything quite well... Well… Almost everything...

The tapes I was using became exclusively Maxell XLI and XLII C-90's -- which consistently worked flawlessly. (The rare time I get them out, those tapes still play fine today.)

The problem was when I attempted to use what should have been a competitive tape -- the TDK SA-90's. (Regardless of brand, I stayed away from the C-120s and rarely had reason to use a C-60.)

Any attempt to use a TDK SA-90 (including brand-new right out of the wrapper) would within seconds result in the tape drifting off path and being eaten. If the tape had already been recorded, I could hear the highs fade out followed by that crunch crunch crunch sound. Every single time.

I don't recall the TDK having the appearance of being a thinner tape -- at least as far as less tape volume on the reels shown through the windows.

45 years later and with an engineering degree behind me, it remains a mystery to this day as to what the difference was between those two tapes when used in that machine. The TDK always let me down and the Maxell never let me down. Both worked just fine on my brother's Sankyo (not Sanyo) top loading deck (scroll down).

CTF-2121.jpg

Sankyo STD 1510.jpg
 
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