Tascam 22-2 Play/Record Issues

[periol]

I'm a relative newb to the analog tape world, but I'm learning fast. Anyways, I'm having a problem, and I can't seem to find an answer anywhere.

I purchased a used Tascam 22-2 about six months ago. It *looks* like it's in very good condition, even when I take it apart and inspect the insides. I've had the same problem since day one though, and it's not going away no matter what I do...

Basically, any tape I put in will FF and REW just fine, but when I play/record it works for a bit then slows down and finally stops. At the beginning of the tape, it will actually go too fast, and then adjust to the right speed, and finally start to slow down after about two minutes. It comes to a complete stop about five minutes into the tape.

I've tried used and new (as in unopened) Scotch 207s, same with Scotch 150s, and I've also purchased and been testing lately with brand new RMG LPR-35 tape. Same deal with all of them. I've cleaned and cleaned again everything the tape contacts, used some Rubber Renew on the pinch roller, and replaced the captstan belt, all with no luck. The new capstan belt is working great, but my visual inspection of the rest of the machine isn't turning up any culprits.

Any ideas?

 

[Steenamaroo]

Not to second guess you, but how do you know it goes too fast?
Do you have good reference tapes from another machine or something?


I had an akai cassette machine that did exactly the same thing. I never fully got to the bottom of it, but I'm fairly sure the hall effect sensors had failed.

The 22-2 has an FG dc servo capstan motor, right?
That'd lead me to believe you're looking at replacing it.

If it is only slowing down then that might be a different thing, but if it deviates both sides of normal speed, I can't think of another reason.

Stay tuned for the pros. I'm just a tinkerer with a 22-2.

 

[jpmorris]

What can sometimes happen is that if the pinch roller isn't working properly - e.g. the actual pinching doesn't have enough force, the reel tension can overwhelm it, especially at the start and end of the tape. That can make the tape play back faster than normal.

A good experiment to try is pushing the pinch roller and seeing whether the speed normalises. (I mean pushing it by the cap - obviously pushing the roller itself won't help!)

 

[toddyjoe]

I have encountered those same symptoms three different times, none of which involved a Tascam 22-2. One time it was a sticky-shed tape problem, but that does not sound like your situation given the tape formulas you are using and your repeated cleaning of the tape path.

A second time it was dirty reel motors that had not been lubricated in a long time. As the motors ran for awhile they would start to heat up due to the dirt and lack of oil and eventually would slow down and stop. The motors looked dirty and dusty and were very hot to the touch after they stopped, so I opened them up, cleaned them out, followed the manual as to proper lubrication amounts and lubrication points and they worked fine after that. The motors and bearing were also a bit noisy before cleaning and lubricating them, but I do not know if that symptom would necessarily be true in every case. In this situation I did not have any initial problems with rewinding or fast-forwarding, but then again I was never rewinding or fast-forwarding any tape for five minutes straight. Of course, once the motors would heat up and stop after playback/recording the rewind and fast-forward would no longer work either.

The third time was an Otari with an old, failing run capacitor on one reel motor. Basically the cap was old and drying up and could not hold a charge sufficient to keep the take-up motor running. After tracking down some replacement run capacitors and installing them, problem was solved. Again, there was no problem with rewinding and fast-forwarding when I initially powered the machine on. Even after the machine stopped playing due to playback I could still rewind and fast-forward somewhat, but it took more time for the rewind and fast-forward to start and get up to speed.

Both of the machines with the mechanical issues above were older machines like a Tascam 22-2 is nowadays. Both machines were also three-motor machines -- two reel motors and a single capstan motor -- like a Tascam 22-2. I am purely speculating here, but if you have a bad run capacitor on a source reel motor I suppose it could cause playback to be too fast at first as there may not be enough reverse torque and counter-resistance being provided by the source motor as is usual on playback. However, slowing down after extended playback/recording would also suggest to me that a take-up reel motor could have a bad run capacitor too.

You did not mention this but I thought the Tascam 22-2 has different tape speed settings? Do you have problems at all tape speeds or just one? If the problem is isolated to one speed setting, I would turn my suspicions after from reel motors, capacitors, belts, etc. and start suspecting issues with a DC servo capstan circuit, which could mean problems with a speed switch, circuit board part or capstan motor winding for one particular speed. Voltage measurements and oscilloscopes then become your favorite troubleshooting friends, so it probably makes sense to see if you have problems with all tape speeds before you start ripping stuff apart.

 

[periol]

Not to second guess you, but how do you know it goes too fast?
Do you have good reference tapes from another machine or something?


I had an akai cassette machine that did exactly the same thing. I never fully got to the bottom of it, but I'm fairly sure the hall effect sensors had failed.

The 22-2 has an FG dc servo capstan motor, right?
That'd lead me to believe you're looking at replacing it.

If it is only slowing down then that might be a different thing, but if it deviates both sides of normal speed, I can't think of another reason.

Stay tuned for the pros. I'm just a tinkerer with a 22-2.

Hey thanks man. Feel free to second guess, I have a manual but still feel like a blind man here!

Anyways, some of the tapes I've tried have stuff recorded on them already, and I've been listening in on headphones during playback. They start playing at warp speed, and then slow down. This is only at the very beginning of the tape, but still...

 

[periol]

What can sometimes happen is that if the pinch roller isn't working properly - e.g. the actual pinching doesn't have enough force, the reel tension can overwhelm it, especially at the start and end of the tape. That can make the tape play back faster than normal.

A good experiment to try is pushing the pinch roller and seeing whether the speed normalises. (I mean pushing it by the cap - obviously pushing the roller itself won't help!)

OK, I'll try. I should mention, the majority of the problem is the tape going too slow. It only plays too fast for not quite a minute or so at the beginning of the tape. I've wondered about that pinch roller though, so I'll check it out.

 

[periol]

I have encountered those same symptoms three different times, none of which involved a Tascam 22-2. One time it was a sticky-shed tape problem, but that does not sound like your situation given the tape formulas you are using and your repeated cleaning of the tape path.

A second time it was dirty reel motors that had not been lubricated in a long time. As the motors ran for awhile they would start to heat up due to the dirt and lack of oil and eventually would slow down and stop. The motors looked dirty and dusty and were very hot to the touch after they stopped, so I opened them up, cleaned them out, followed the manual as to proper lubrication amounts and lubrication points and they worked fine after that. The motors and bearing were also a bit noisy before cleaning and lubricating them, but I do not know if that symptom would necessarily be true in every case. In this situation I did not have any initial problems with rewinding or fast-forwarding, but then again I was never rewinding or fast-forwarding any tape for five minutes straight. Of course, once the motors would heat up and stop after playback/recording the rewind and fast-forward would no longer work either.

The third time was an Otari with an old, failing run capacitor on one reel motor. Basically the cap was old and drying up and could not hold a charge sufficient to keep the take-up motor running. After tracking down some replacement run capacitors and installing them, problem was solved. Again, there was no problem with rewinding and fast-forwarding when I initially powered the machine on. Even after the machine stopped playing due to playback I could still rewind and fast-forward somewhat, but it took more time for the rewind and fast-forward to start and get up to speed.

Both of the machines with the mechanical issues above were older machines like a Tascam 22-2 is nowadays. Both machines were also three-motor machines -- two reel motors and a single capstan motor -- like a Tascam 22-2. I am purely speculating here, but if you have a bad run capacitor on a source reel motor I suppose it could cause playback to be too fast at first as there may not be enough reverse torque and counter-resistance being provided by the source motor as is usual on playback. However, slowing down after extended playback/recording would also suggest to me that a take-up reel motor could have a bad run capacitor too.

You did not mention this but I thought the Tascam 22-2 has different tape speed settings? Do you have problems at all tape speeds or just one? If the problem is isolated to one speed setting, I would turn my suspicions after from reel motors, capacitors, belts, etc. and start suspecting issues with a DC servo capstan circuit, which could mean problems with a speed switch, circuit board part or capstan motor winding for one particular speed. Voltage measurements and oscilloscopes then become your favorite troubleshooting friends, so it probably makes sense to see if you have problems with all tape speeds before you start ripping stuff apart.

There are two speed settings, 7.5 and 15 ips. I've tried using both settings with no luck getting the tape to keep playing, though I haven't tested from the beginning of the tape.

I've kind of figured this is probably due to one of the motors, either the take-up motor or the capstan motor. That said, the capstan motor keeps going no matter what, at what seems to the naked eye to be a pretty constant speed, whereas the reels themselves just stop turning eventually.

Lubrication of the take-up motor was probably my next step, so I'll try to take a more thorough look at that and report back. Thanks.

 

[Steenamaroo]

That said, the capstan motor keeps going no matter what, at what seems to the naked eye to be a pretty constant speed, whereas the reels themselves just stop turning eventually.

Hold on, the capstan spins away but the reels halt? So eventually the capstan would be spinning against static tape?
Check out the pinch roller as above first. JPmorris might have hit it on the head.


If not, what you're saying rules out issue with the capstan motor AFAIK, and it also rules out any take up issue because the tape would go slack on the takeup side and play would stop dead if there was a problem there.

Could this be a friction problem. The brakes binding, maybe?

While the machine is grinding to a halt, have a feel to see if the supply reel is hard to 'encourage'.
If it is, but becomes completely free when you hit stop, it could well be that.

 

[periol]

What can sometimes happen is that if the pinch roller isn't working properly - e.g. the actual pinching doesn't have enough force, the reel tension can overwhelm it, especially at the start and end of the tape. That can make the tape play back faster than normal.

A good experiment to try is pushing the pinch roller and seeing whether the speed normalises. (I mean pushing it by the cap - obviously pushing the roller itself won't help!)

This is totally the problem. As soon as I put a little pressure on the pinch roller, everything starts working normally.

It looks like the plunger/spring that goes into the solenoid is not quite pulling enough on the pinch roller to bring it into contact with the capstan shaft.

Now I just have to figure out how to adjust that. What a relief to actually see what the problem is.

THANKS

 

[Steenamaroo]

Congrats, and nice one JPmorris!

 

[periol]

And I got it adjusted. Wow. Sometimes I'm too stubborn for my own good, I've been pulling my hair out over this one. Thanks again everyone, and especially JPmorris! WOOHOO!

 

[A Reel Person]

!!!...

This is totally the problem. As soon as I put a little pressure on the pinch roller, everything starts working normally.

It looks like the plunger/spring that goes into the solenoid is not quite pulling enough on the pinch roller to bring it into contact with the capstan shaft.

Now I just have to figure out how to adjust that. What a relief to actually see what the problem is.

THANKS

I'm not gonna posture and say that was my diagnosis,...
oh wait, yes I am!!
too late on the trigger here, I guess!