TEAC A-2340 Slowing Down

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Robert Smyth

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I've recently acquired a TEAC A-2340 that works well except for one problem. After about 20 minutes of play, the unit starts to gradually slow down.

I assumed that the belt was likely loose and needed to be replaced. Before ordering a belt, I opened the unit to verify that was the problem. The belt is fine. I checked the motor to see if it was seizing from the heat or lack of lubrication but it seems fine.

It seems that it must be an electrical issue that happens after the unit warms up.

Has anybody seen this kind of behavior.

Robert
 
What tape are you using on the deck?

Tape that's in the early stages of sticky shed syndrome will make a deck behave pretty much as yours is. And in advanced stages of decay, will shed excessively, produce squeaking sounds and can bring the whole deck to a dead stop if sticky enough.

Cheers! :)
 
Yep exactly! And as the supply reel becomes smaller in diameter from the tape moving to the take-up reel, the friction of the bad tape against the tape path becomes more significant due to greater torque of the smaller spool on the supply side. 20 minutes into the tape at 7.5 ips is getting close to halfway through the tape and this is a pretty common spot for sticky-shed tape to audibly slow down a tape deck or stop it dead. It could be other problems, but bad tape is by far the most common issue, so explore that first.
 
Thanks for the quick responses.

I have three tapes that all have the same issue.

Tape 1: Maxell UD-XL 35-90B
Tape 2: Ampex GM 456
Tape 3: Cat Stevens - Greatest Hits (Old pre-recorded tape)

I'm not sure of the age of the maxell and ampex but the cat stevens tape has to be almost 40 years old.
I found it in a salvation army for $2.

The Cat Stevens tape is physically very short. (about 20 minutes per side at 3.75 ips).
The inner reel is larger than a normal reel.
It sounds surprisingly well for such an old tape.

I tried a few things and if I stop and power off the unit at the halfway point for about 10 minutes and start it back up, it plays fine only to slow down again after about 20 minutes.

I will need to at least buy a few new tapes to test this theory out. I would love to avoid shelling $40 for a new motor.

Any suggestions on tape brand/type for this deck?

Bob
 
This is a pic of the large inner reel of the pre-recorded tape...... IMG_0883.webp
 
The Ampex GM 456 will almost certainly have sticky-shed syndrome. The Maxell will not no matter how old it is. However, if you have one tape shedding on the tape path it can contaminate other tapes with the shedding material. The reel for the prerecorded Cat Stevens tape is designed that way to be low-torque.

You may have other problems related to component heating and lubrication, but first clean the entire tape path thoroughly with 91% or higher isopropyl alcohol, or denatured alcohol (my preferred tape path cleaner). Then buy a new sealed tape. The new tape can be new-old-stock (NOS) as long as its sealed and not prone to sticky-shed.

Tapes that are good for testing (that machine) include, but are not limited to the following:

Quantegy 407, 457, 642
BASF or EMTEC LPR35 and LP35
RMGI LPR35
Radio Shack/Realistic Supertape 1800, Number 44-1877 or 44-1877A (Same as Ampex/Quantegy 642)
Scotch 207 and 229
Maxell UD 35-90 and XL 35-90B
 
I will definitely try a new tape(s) and give the tape path a good cleaning. I'll also look into lubrication. I have the service manual for the machine and there is a lubrication section that's pretty detailed.

Thanks for the info.

Robert
 
One other quick thing to try before or after you get new tape is to clean the capstan and pinch roller really well. Oxide buildup here can cause the tape to slip (so can a slick hardened pinch roller). In the beginning the tape will play a bit faster than normal, but will slow over time. The reason is in the beginning the take-up reel is helping to pull the tape along... which it should not be doing. And after a while the take-up reel slows down because its heaver full of tape and again the back tension torque of the supply reel increases. In a properly functioning tape deck the tape should only be moved forward in play or record by the action of the capstan and pinch roller, which keeps it at the correct steady speed. The take-up reel should only have just enough take-up tension to keep up with the speed at which the capstan/pinch roller are moving the tape, so the tape won't spill too quickly for the take-up reel to pick it up. Likewise the only function of the supply-reel back tension should be to keep the tape from spilling off so quickly that the tape-to-head contact is compromised.

If this is still a problem after you've cleaned the pinch roller and capstan, then try lifting up on the pinch roller arm so it is more firmly pinching the tape between it and the capstan. You should see the speed restored to normal while holding it up into position. There are also more complicated mechanical problems that can cause the pinch roller not to engage the capstan with enough tension.
 
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