Capstan/Pinch Wheel problem....

treidm

treidm

Spinning Wheels
On my freebie, experimental deck, that was given to me, I have been experiencing a problem.

Preface Details:
1/4", 1/4 track, 7" reels.
Manually cleaned interior & exterior,
Cleaned heads etc...
Demagnetized heads.
Using brand new Quantegy 407 1mil tape.
Recording at 7.5ips

At times, Tape will spit itself out towards you, from between the capstan & pinch wheel, when playing or recording. More often happens at beginning of reel, when take up reel is empty.

If you are deep enough into reel, it usually will operate ok.
Sometimes it will operate ok, wherever you are, even at the beginning, where it more often, is at its worst.

Oh yes, Unloaded/Loaded tape multiple times on reels, at play speed & rew/ffw speeds, to see if there was a difference.

The rew/ffw repacking actually acts up less, but not by a large margin.
(After unpacking, I always try to repack digital tapes or cassettes at play speed, thought the same could be true for reels.)

Also tried different reel combinations ie. swapping sides, flipping, changing which two reels are together. (Limited to the three plastic reels that I have, so not that many combo's, but tried anyway :D)

What adjustments need to be made, to correct this problem?



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One possibility is the rubber pinch roller may be hardened and slick or covered with a layer of residue that won’t come off with alcohol. It could also be weak pinch roller tension. Have you cleaned the pinch roller with a cotton-tip while it's spinning.

To clean it push play while holding the right tension roller up (with no tape on the machine of course). Use Windex on a cotton-tip (Q-Tip) as the roller spins.

For best results get something like RBR Caikleen

http://www.cyberguys.com/templates/searchdetail.asp?productID=3127

You can also try some printer roller cleaner from an office supply store.

Examine the pinch roller for cracks. It should not be hard and slick, but have the feel of a rubber tire.

The pinch roller could be beyond repair and you’ll need a new one.

:)
 
Beck said:
One possibility is the rubber pinch roller may be hardened and slick or covered with a layer of residue that won’t come off with alcohol. It could also be weak pinch roller tension. Have you cleaned the pinch roller with a cotton-tip while it's spinning.

To clean it push play while holding the right tension roller up (with no tape on the machine of course). Use Windex on a cotton-tip (Q-Tip) as the roller spins.

For best results get something like RBR Caikleen

http://www.cyberguys.com/templates/searchdetail.asp?productID=3127

You can also try some printer roller cleaner from an office supply store.

Examine the pinch roller for cracks. It should not be hard and slick, but have the feel of a rubber tire.


The pinch roller could be beyond repair and you’ll need a new one.

:)
Click to expand...
When I cleaned deck, I used 99% Isopropyl. I only cleaned quickly on rubber parts, because I thought the alchohol might damage, and dry out rubber. My mistake.

The pinch roller rubber, is very soft and pliable.

As far as tension, I'm not familiar with how strong the pinch roller should be. I could easily stop it from spinning, with a moderate amount of pressure, but it seems to have enough power to transport tape. The capstan, though, has lots of torque.

I just tried the windex, and you were correct. The moderate alchohol cleaning I did, didn't break down and release what was on rubber. Gone thru 15 Q-tips, and THICK INKY black still coming off.

Should I continue until a Q-tip is completely clean while rubber roller is spinning on it?
Not very familiar with cleaning rubber.
Thought maybe the windex would be breaking down the rubber, and keep showing black on Q-tip, and I should stop after a while.

Thx for help...:)


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cjacek said:
You should also look into having the pinch roller rubber replaced. See here: http://www.terrysrubberrollers.com/
Click to expand...
Well, problem is, this is a freebie, which isn't what I want. Will be buying a deck that suits me, so don't want to spend a bunch of money, on what would have been a temporary, experimenting/learning deck. I will donate it locally to someone that wants a deck of this type, and doesn't mind it being a bit of a project.

I was just hoping this deck could work enough to practice on, before I get a deck that fits my needs & budget.



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Could also be the rubber is too soft... the other extreme of what can go wrong with rubber rollers. Unless there's some serious residue from never being cleaned you shouldn't have black coming off indefinitely.

Try a final application of windex and then use dry Q-tips until there's little or nothing coming off. That should do it if the rubber is salvageable.
 
treidm: Oh yeah, I definitely understand but all rubber of this vintage should be ideally replaced. A bad pinch roller, not to mention belts, are the most common problem one has with an older tape deck. It causes lots of tape handling (and playback/recording) problems, as you may have already found.

I had a similar Akai deck to yours and recall I only had to treat it (pinch roller) with a special rubber cleaner. It not only cleaned but restored the pinch roller's grip and all worked flawlessly.

If, on the other hand, you have a pinch roller which is coming appart, too soft and gummy, then obviously a replacement is the only solution.
 
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cjacek said:
treidm: Oh yeah, I definitely understand but all rubber of this vintage should be ideally replaced. A bad pinch roller, not to mention belts, are the most common problem one has with an older tape deck. It causes lots of tape handling (and playback/recording) problems, as you may have already found.

I had a similar Akai deck to yours and recall I only had to treat it (pinch roller) with a special rubber cleaner. It not only cleaned but restored the pinch roller's grip and all worked flawlessly.

If, on the other hand, you have a pinch roller which is coming appart, too soft and gummy, then obviously a replacement is the only solution.
Click to expand...

cjacek:

Rubber is very pliable, but doesn't look to be too soft or coming apart. After cleaning some more with windex, then dry Q-tip, tried it out. The tape spitting out, is now fixed. But did notice, that takeup spindle in slightly bent. I can fix that tomorrow at work bench. But tape spitting from capstan/pinch wheel has stopped.

Now have new problems :D

After recording a mixdown to deck. The playback seems to drag a little. And dB level is about 6dB less at playback on right channel & 3 to 4dB less on left channel at playback.

Does the dragging indicate, maybe I am not done cleaning, or could try something like Caig caikleen RBR, that was mentioned ealier?

Or just quit trying, because it needs a new pinch roller, and give it away? :(


ps: Before, when I could get it to run without spitting tape, the level differences were there, but there was no dragging, like it does now.

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Apart from, or in addition to pinch roller condition and pressure, reel tensions can have a big effect. You say the problem was worse at beginning of reel. It usually is because take up tension is greatest and supply reel tension smallest. That's the worst combination. Just using your finger, gently put some drag on the take up reel, and/or do the same to the supply reel (on a tape not important of course). You should see less tape waver or it may stop altogether.
This is a major cause of tape chews with thinner based tapes and a real problem with cassette machines which of course use thin tapes.

Reel tensions should be adjusted as per service manual figures, using a spring balance and a suitable piece of cord on the specified diameter reel hub.
Machines with mechanical reel tension, often felt clutches, can go high or low. Problems should be less common with 3 motor machines.

Cheers Tim.
 
Tim Gillett said:
Apart from, or in addition to pinch roller condition and pressure, reel tensions can have a big effect. You say the problem was worse at beginning of reel. It usually is because take up tension is greatest and supply reel tension smallest. That's the worst combination. Just using your finger, gently put some drag on the take up reel, and/or do the same to the supply reel (on a tape not important of course). You should see less tape waver or it may stop altogether.
This is a major cause of tape chews with thinner based tapes and a real problem with cassette machines which of course use thin tapes.

Reel tensions should be adjusted as per service manual figures, using a spring balance and a suitable piece of cord on the specified diameter reel hub.
Machines with mechanical reel tension, often felt clutches, can go high or low. Problems should be less common with 3 motor machines.

Cheers Tim.
Click to expand...

Tim:

I re-cleaned everything, previously cleaned, and with windex, thoroughly cleaned rubbers. Still didn't help. (Good to do though, as rubbers needed it badly)

Did as you said, and tried light pressure on reels. Pressure on the take-up reel, made no difference, that I could see in the wavering. Pressure on the supply reel, almost stopped it from wavering completely on supply side of capstan. It still had some slight wavering on take-up side of capstan, but pressure on T-U side, did not stop the small wavering it did. Doing this, will keep it from spitting tape out, even at very beginning of tape.

I explained that this deck is a freebie, and not what I want, so it's an experimental deck. I don't want to sink alot of $$ in it, but will spend as much research, sweat & time as needed, if it will help. Probably will anyway, as I love learning new things.

Where can I learn about fixing tape tension. the manual with this deck, is very limited in it's content. Is there any info out there, that I can study up on?

Are service manual figures, only in "service manual", that I don't have? And could you be more specific as to type and size of spring balance? :D

Thx....Reid

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treidm said:
Tim:

I re-cleaned everything, previously cleaned, and with windex, thoroughly cleaned rubbers. Still didn't help. (Good to do though, as rubbers needed it badly)

Did as you said, and tried light pressure on reels. Pressure on the take-up reel, made no difference, that I could see in the wavering. Pressure on the supply reel, almost stopped it from wavering completely on supply side of capstan. It still had some slight wavering on take-up side of capstan, but pressure on T-U side, did not stop the small wavering it did. Doing this, will keep it from spitting tape out, even at very beginning of tape.

I explained that this deck is a freebie, and not what I want, so it's an experimental deck. I don't want to sink alot of $$ in it, but will spend as much research, sweat & time as needed, if it will help. Probably will anyway, as I love learning new things.

Where can I learn about fixing tape tension. the manual with this deck, is very limited in it's content. Is there any info out there, that I can study up on?

Are service manual figures, only in "service manual", that I don't have? And could you be more specific as to type and size of spring balance? :D

Thx....Reid

.
Click to expand...
What make and model tape machine was it again?
As a general idea, the take up tension should be considerably less than the Fast Forward tension. You can get an idea by braking the edge of the take up reel with your hand in each mode and get a feel for the difference. With the supply reel, try to turn the reel anticlockwise while there is no tape on the machine and it's in play.(may have to temporarily fool tape shut off arm etc with a rubber band holding it in position). It depends on the machine how much back tension there should be. A 3 motor machine will actually gently turn the reel backwards while a non 3 motor machine might just have a slight braking effect when the reel is being pulled around by the tape.
What does the capstan shaft look like? Is it clean? After much use the shaft can get a groove worn in it, or even just slight ridges which can make the tape ride up them. Just inspect it carefully, perhaps with a magnifier.

I use 300gm and 3kg spring balances but that's been my paid work as a tech. It's up to you whether you want to go to the hassle of getting these when you said this deck is just experimental.


Changing the tensions on non 3 motor machines can be a hassle. There can be springs, felt pads and discs, little washers which must be replaced in exactly the right order, horrible little e-clips which can be easily damaged, sometimes experimenting with different thickness spacer washers to get tensions within specs, cleaning and/or replacing felt pads and rings. In short it can be a lot of messing around. And the manuals dont always tell you all you want to know. OTOH if it's just experimental and a hobby, what have you got to lose? if you do start removing E-clips etc be very careful where they ping off to. You could lose them or they could end up in your eye. You need good small tools too and good eyesight.

Anyway hope this helps.

Tim
 
Tim Gillett said:
What make and model tape machine was it again?
Tim
Click to expand...

AKAI GX 220-D
Glass & X'Tal-head
1/4", 1/4 track.
7" reels
3-speeds(7.5ips highest)
records, one direction, plays both
SOS recording
Some switch on it called S.R.T., Have no idea, about that one.
I will read the rest of your post, now....Thx

Reid


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Reid,
I think that model had three motors, ie: direct drive motors on the reels.
It's less likely for the reel tensions to go out as it's not dependent on clutches going out of tolerance.
I'm not sure what else to say other than what's already been said.

Tim
 
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