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  #41  
Old 11-30-2016, 03:30 AM
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keithatrochdale keithatrochdale is offline
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Right to me the capstan is in a very dirty state, give it a really good clean and try again.

Is the rest of the tape path in the same disgusting state, if so give it all a really, really good clean and see if that helps.

I would also be giving the pinch roller a very gentle clean with some 600 wet and dry. The tape may have made a slight indent in it causing it not to grip the tape properly.

If you need to re-surface the capstan, but I doubt it after these steps, do a search on the forum. The sandpaper rolls round the pinch roller while it rotates and pushes against the capstan - it is not held against it as if to "sand it down".

.
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  #42  
Old 11-30-2016, 06:29 PM
eddisc eddisc is offline
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>>>spinning the roller, I might get 2-3 full rotations with one hard swipe.<<<

Mine spins many many more times than this. IF pivot points have never been cleaned and relubed, that could very well be the root cause.
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  #43  
Old 11-30-2016, 07:25 PM
tpir72 tpir72 is offline
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Thanks for all the feedback. So the photo is taken after the roller and capstan was cleaned with brand new tape head cleaner solution and Q-Tips. I'm at the point where nothing else is showing up on the Q-Tips.

Should I use something else to clean both without damaging anything? I have read several suggestions here and on the internet but would appreciate suggestions.

I did remove the pinch roller clean and lube but still only get 2 or 3 rotations with a swift finger swipe.
  #44  
Old 11-30-2016, 09:08 PM
eddisc eddisc is offline
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Quote:
Originally Posted by tpir72 View Post
Thanks for all the feedback.
I did remove the pinch roller clean and lube but still only get 2 or 3 rotations with a swift finger swipe.
You're welcome... sooner or later we'll nail it!
I just went to the storage closet here @ work (major FM sta.) and spun a closet unit that's been sitting for ~ 8-10 yrs & it went for 3-5 seconds...
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  #45  
Old 12-01-2016, 01:17 AM
tpir72 tpir72 is offline
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Thanks for checking the spare unit. I'll pick up some lithium grease tomorrow and start with a full clean & lube of the Pinch Roller again.

Will see if I can find a scale locally to do the test, if not Amazon I go...

This has been so much fun for me and I'm sure everyone here is getting sick of dealing with the reel-to-reel forum newbie....

Heads up everyone, a major TV network has loaned me a couple of actually working MacKenzie cart machines to help recover a couple hundred carts from 1966 forward. Prepare for endless obscure questions about MacKenzie decks...

Regards,

Terry
  #46  
Old 12-01-2016, 01:25 AM
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tapetech tapetech is offline
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I don't think there is anything wrong with your pinch roller bearing based on your report. BTW, you don't use grease to lube a pinch roller bearing.

Photo is not great, but I see nothing wrong with the pinch roller or capstan as far as cleaning.

Try resurfacing (embossing) the capstan. It looks polished.

-cover the pinch roller with double-sided cellophane tape. Don't overlap tape.

-then wrap ~150 grit sandpaper around the roller. Don't overlap the sandpaper.

-run deck in play for 5 minutes to emboss the capstan shaft. It should now have a mat finish.

To really test a deck's absolute speed and speed stability (drift) and speed oscillations (wow/flutter) you need an MRL speed tape and a wow/flutter analyzer. Anything less, and you are just sort of guessing if the deck is good or not (speed-wise).
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Last edited by tapetech; 12-01-2016 at 01:27 AM.
  #47  
Old 12-01-2016, 01:58 AM
tpir72 tpir72 is offline
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Thank you very much, I have a lot to consider with this and how much money I really want to throw at this
  #48  
Old 12-01-2016, 08:10 AM
cornel cornel is offline
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A simple way to check the speed is to ask a friend who still owns a tape recorder to record a signal of certain frequency ( could be 1000 Hz ) from an audio generator or even from computer and play the tape on your machine while checking the frequency with a frequency meter or using your computer.
I do not remember if sticky tape syndrome has been excluded in your case - did you try with another tape ?
Is the left hand impedance roller spinning free ?
Is the left break completely disengaged in Play mode ?
  #49  
Old 12-01-2016, 01:15 PM
eddisc eddisc is offline
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Quote:
Originally Posted by tapetech View Post

Try resurfacing (embossing) the capstan. It looks polished.

-cover the pinch roller with double-sided cellophane tape. Don't overlap tape.

-then wrap ~150 grit sandpaper around the roller. Don't overlap the sandpaper.

-run deck in play for 5 minutes to emboss the capstan shaft. It should now have a mat finish.
IF the p/r is not making full contact - as stated several times, how will embossing the capstan help? NOT trying to be a smart ass - just asking... m/b I'll learn somethin'
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  #50  
Old 12-01-2016, 01:27 PM
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Quote:
Originally Posted by eddisc View Post
IF the p/r is not making full contact - as stated several times, how will embossing the capstan help? NOT trying to be a smart ass - just asking... m/b I'll learn somethin'
His statement that it's very difficult to stop the pinch roller by hand when in play indicates that the pinch roller pressure is correct or at least close to spec. For pinch roller pressure, close is good enough. It is not a critical spec I have found over the years. If, however, PR pressure is only 20% of spec, then yes, that would cause a problem and it would be quite easy to stop the PR by hand.
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Last edited by tapetech; 12-01-2016 at 01:30 PM.
  #51  
Old 12-01-2016, 11:39 PM
eddisc eddisc is offline
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Quote:
Originally Posted by tapetech View Post
His statement that it's very difficult to stop the pinch roller by hand when in play indicates that the pinch roller pressure is correct or at least close to spec. For pinch roller pressure, close is good enough. It is not a critical spec I have found over the years. If, however, PR pressure is only 20% of spec, then yes, that would cause a problem and it would be quite easy to stop the PR by hand.
my thanks !!
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  #52  
Old 12-02-2016, 12:15 AM
tpir72 tpir72 is offline
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Thank you all for the help! I have a few things to work on with your suggestions this weekend. There was a mention of using a spring scale to check the pinch roller pressure. I have looked at Harbor Freight Tools, Lowes and Home Depot for a cheap spring scale. We have a Bass Pro Shops here, would a cheap fish scale work or can you recommend something from Amazon?

https://www.amazon.com/s/ref=nb_sb_n...s=spring+scale
  #53  
Old 12-02-2016, 09:15 AM
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Terry,

Check your PM's here on Tapeheads.

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  #54  
Old 12-03-2016, 12:19 AM
tpir72 tpir72 is offline
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Pinch Roller Forensics

Ok, I had a nice chunk of time tonight to reread all the replies and examine everything again.

Two things were a pinch roller question mark, was it a different cap and were both shims in the correct order/place.

The pictures are not great but I observed wear inside the cap and no thin shim between the cap center and the brass roller center. Since I had never taken this cover off before starting this thread, it appears it was never there.

If you look at the pinch roller arm the top out of focus arm, there appears to be a lock ring on that arm and the arm doesn't rotate but the only shim was between the roller brass center and that lock ring. There is definite wear on the rear aluminum portion of the roller.

The other question is the copper or brass ring inside the aluminum pinch roller supposed to be independent and free-wheeling like a bearing? It is not.

The only shim I have is the one wafer-thin piece that was between the lock ring and the roller.

I'm wondering if I should make new shim from this: https://www.mcmaster.com/#teflon-(ma...ptfe)/=15axwh9

And other post guides from this: https://www.mcmaster.com/#teflon-(ma...ptfe)/=15axxti

Thoughts gang???

Regards,

Terry
Attached Images
File Type: jpg Cap Front.jpg (32.7 KB, 11 views)
File Type: jpg Cap Inside.jpg (37.3 KB, 9 views)
File Type: jpg Cap - Side View.jpg (21.2 KB, 10 views)
File Type: jpg Pinch Roller Arm with Rear Guide.jpg (37.4 KB, 11 views)
File Type: jpg Rear Washer-Shim.jpg (53.0 KB, 9 views)
File Type: jpg Roller Front.jpg (46.9 KB, 10 views)
File Type: jpg Roller Rear.jpg (46.2 KB, 10 views)
  #55  
Old 12-04-2016, 01:51 AM
eddisc eddisc is offline
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>>>The other question is the copper or brass ring inside the aluminum pinch roller supposed to be independent and free-wheeling like a bearing? It is not.<<<

No, it is not supposed to be 'freewheeling'. THAT is the sintered bronze bushing which provides the "bearing" surface for smooth, friction reduce spinning. IIRC there needs to be a shim or spaced on the shaft and one under the cal. In other words - one on each side of the bronze bushing.
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  #56  
Old 12-04-2016, 02:49 AM
cornel cornel is offline
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Your upper shin is missing !
Put the machine in play mode without the roller black aluminium lid.
Test with tape and hear for correct speed .
If OK , put the lid back and screw just for blocking the lid , without friction between the lid and the roller hub.
Pay attention , the pinch roller can be put on opposite way on its shaft , but just one position is the correct one , where the shaft of capstan goes out from the inner whole of roller hub just one milimeter or so , in order for a shin/spacer to fit between the lid and the roller hub.
  #57  
Old 12-04-2016, 05:33 PM
tpir72 tpir72 is offline
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Thank you very much. I'll try this experiment this evening.

If you happen to have a set of calipers what size should the upper shim be?

It looks like the rear one is 0.001 inches thick.
  #58  
Old 12-04-2016, 10:50 PM
cornel cornel is offline
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My original shim has been lost long time ago...
I have made one using a plastic ( I guess was polyethylene foil ) , possible 500 microns width, not sure .
But I noticed the friction force between roller and the upper lid is very sensitive to outer diameter and width of the upper shim.
So , you can try yourself some hand made shims and screw just a little bit the upper lid on the capstan shaft.
Did you check if left brake is completely disengaged when in play mode ?
What about the impedance roller ? Does it spin freely ? Are you sure is not about a sticky tape syndrome ?
  #59  
Old 01-09-2017, 07:32 PM
tpir72 tpir72 is offline
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Cart Machine?

Happy Holidays Everyone!

The Otari MX5050 speed dips are still an issue. I have had to put further tweaking/testing on hold. A friend loaned me a Teac to digitize everything so I could get the library back to the owner's storage. I do want to revisit the issue after everything is done.

Unrelated question, and not trying to take this off topic...

Also in the tape library are a bunch of plastic, 1/4 inch tape cartridges. Is there a propper place to ask if any members at Tapeheads has a working player they no longer want? I'm told it was used for Radio & TV and may have been called an NAB Cart Machine???

Thank you very much!

Regards,

Terry
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File Type: jpg Cart Image.jpg (87.3 KB, 4 views)
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