FF/REW fix ctf-8282,9191,1000 RXA-581, NOT DIY

[markthefixer]

ON HIATUS. I AM STILL IN HOSPITAL SINCE 9-9-23 IT'S 3-21-2024


I AM VIRTUALLY INCOMMUNICADO

I don't want to spread false hopes:
All is not well, i may never even get out, no less home- I'm being forced to sell my house..
modern medical nursing care is gonna suck me dry. leave me dependent upon illinois "programs"
i,m starting to envy the mode of merlynski's demise.
i'm not 'bouncing back' like i did the last time in 2012, typing this much is difficult, explanations in depth are hard to do
and there are other things going on behind the scenes that consume daily budget of effort.

August 2023!!!, STILL fixing them, to contact me about the Clutches, PLEASE PRIVATELY MESSAGE me on AudioKarma's (Private) " Start a Conversation" message system, please do not post that question at the end of this thread. That would constitute commercial activity and get this thread disappeared. As it is, this notice comes perilously close.

To start a Private Conversation, click on my name under the avatar, then in the pop up box there is a "Start a Conversation" in blue, click on it.

I have learned quite a bit in how to recover clutches that have been mistreated by ad-hoc repair attempts, as well as which clearances to watch like a hawk, as well as a few more to adjust - depending upon how things measure up....
Also even though I am "on hiatus", I have NOT left clutch owners in the lurch, I am STILL fixing clutches (and STV-2,3,4H diodes) even while I am on hiatus (posted Oct 2016).

ON HIATUS. I AM IN HOSPITAL SINCE 9-9-23 IT'S 3-21-2024

I AM VIRTUALLY INCOMMUNICADO


The ctf-8282, ct-f9191 and ct-f1000 cassette decks are built like tanks, with one exception:
The FF / REW idler clutch. It's failure kills the deck's ability to Fast Forward and Rewind tapes.

The idler clutch is allowed to move in two directions (top/bottom of deck, left/right), and depending upon whether the driving tire is turning clockwise or counter clockwise, the idler comes to rest, wedging between the motor drive tire and either the cassette tape supply reel drive or the takeup reel drive and causes that reel to turn - thus Fast Forwarding or Rewinding.



This first (exploded assembly) drawing is of the arm and idler clutch assembly from the ct-f9191 service manual.


But this thing is more than just an idler, it has a clutch (idler "B", RNK-187) built in, to presumably reduce rubber wear when the cassette refuses to move, so instead of tearing up the rubber, the nylon to felt clutch joint slips. This clutch pack(idler "B", RNK-187) is the upper white wheel with the vertical grooves for friction. The motor's tire (looks a bit like a pencil eraser) turns on these vertical grooves. The lower idler with black tire (idler "A", RNK-188) is what hits the supply and takeup reel drives for the cassette.




This is a view of the partially disassembled arm, with the clutch pack (idler "B", RNK-187) on the left. Note the rather strong spring standing better than 1/2 inch tall. On top of that is the spring holder. In the center is the idler (idler "A", RNK-188) that contains (or is supposed to contain) the force of that spring. You can see the black tire on the bottom, and the felt friction/slip material on the flat surface that the post sticks up from. On top of the post is a button that presses on quite tightly, with a friction fit to the post. this friction fit is strong enough to contain (when new) the force of the idler B spring.


With the force contained, the idler a/ idler b assembly is floated OVER the supporting arm by the spring cup and spring shown on the right side, shown ON the shaft that the idler a/b assembly turns on.

That's how it's supposed to work. Time had a surprise for us.

 

[markthefixer]

Surprise!!!! Sproingggg.......
That tight friction fit between the post and the top button got WEAK!!! The assembly now does NOT float over the arm, instead the force of the big spring causes everything to bind - and tear up (formerly irreplaceable) expensive rubber on the drive motor's tire. Some early fixes tried to drive the frozen idler by increasing a spring size elsewhere, to increase the force of the motor drive tire onto the idler. Fail. Tear up that drive wheel really quick. Another fix tried to LIFT the binding surface of the botton of the idler ABOVE the arm. Fail. Still kills that drive tire.




The problem? Look at the post, there's a vertical CRACK in the post, and the part of the button that went down inside the post now just expands the post, rather than generating friction. The nylon dried out and lost some strength, and there IS a lot of tension there, so the nylon just split. The fix, a brass sleeve made out of brass tubing. Reinforces the entire post, the nylon is no longer in tension, it is in COMPRESSION. PASS.
Of course it's a lot of fun cutting something smaller than a pencil eraser, making sure the ends are square (not tilted or wobbly) and getting rid of any burrs inside which would make it impossible to get on, and any burrs on the outside that would make it impossible to get the idler B on. We're talking clearances of 0.001 inches. A lot of machining is 0.005 clearance... AND THEN, to make life miserable, KEEP from knocking the tube out of ROUND while doing all of this... fun...
but I figured it out. Die makers files, stuff like that...





BUT TANSTAAFL: there ain't no such thing as a free lunch..........
That sleeve increases the diameter of the post, and we DO get a freebie, the spring holder (green circle) clears it (edit - NOPE!! it gets bored out too because the button's outer wall expands). BUT the B idler doesn't fit over it. OK, easy enough... open up the hole in the B idler to restore the original clearance (the RED circle) - the sleeve isn't THAT thick..... well... close but no cookie...... LOOK AT THE BUTTON, on the Left.
Here comes the HARD part.



See the "halos", the green circle with the red circle inside of it, we'll get back to them. There is a tall nub that fits INSIDE of the idler B post, THAT'S the friction fit. The green cylinder drawn above it means that not only is the diameter correct, it is the all important friction fit surface that we must PRESERVE AT ALL COSTS.

Then there's the wall around it, forming a groove that the idler B post fits into, OR USED to fit into, until the brass sleeve was added.... OUCH.... so, options: 1. remove the wall, or 2. increase the groove's width (make that wall thinner) WITHOUT hurting the inner surface of the groove. Now we're back at the "halos", the red circle is the outer face of the groove, that must be made wider. The distance between the red halo part and the green halo part will end up being 0.008 inch ( eight thousandths of an inch ) when I'm done cutting..... So, I made another tool. It was a real %^$#^%%^%$ to make.... If I ever have a fire, I'm gonna grab that tool BEFORE the computer....

Note: the shavings around the button and in the groove are the result of stopping in the middle of the groove cutting to take a picture.

Success: this is what a good clutch looks like, the button is holding it all together without the assistance of the center shaft. So far I have done two (edit: aug 2017 - probably over 50 by now). I will do these clutches like I do the STV-2H, STV-3H, STV-4H diodes. I get and fix the broke ones...



and this is what good versus bad looks like when on the arm, the one on the left is good, the one on the right is binding.


this picture was taken FIRST, before the clutch on the right was repaired, all the other pictures are THAT CLUTCH being repaired.... I now have NO binding clutches.



This is the part that is mailed for installation of the sleeve:
The CT-F1000 has a plastic arm versus metal arm shown here. Keep it on, send it.

 

[calman46]

Nice job ,thank you .

 

[tomwil]

Wow, Mark, get writeup!

I just have two questions that didn't seem obvious to me why it would not work.

1) Is it possible to glue the button (RR Idler Bearing RNK-189) to the post (FF Idler A RNK-188)? Even if that post is cracked, it would still hold the retaining spring button via the glue.

I know it would probably be impossible to separate those parts again, but would there be a reason to separate them again in the future?

2) Could a slightly shorter piece of that brass fitting be used, so that the button would still fit on the post tightly without modification and the brass fitting would still not allow the split post to expand?

Again, thanks for a great writeup!

 

[markthefixer]

Wow, Mark, get writeup!

I just have two questions that didn't seem obvious to me why it would not work.

1) Is it possible to glue the button (RR Idler Bearing RNK-189) to the post (FF Idler A RNK-188)? Even if that post is cracked, it would still hold the retaining spring button via the glue.

I know it would probably be impossible to separate those parts again, but would there be a reason to separate them again in the future?

2) Could a slightly shorter piece of that brass fitting be used, so that the button would still fit on the post tightly without modification and the brass fitting would still not allow the split post to expand?

Again, thanks for a great writeup!

Gluing nylon to nylon is difficult, and some people have (regretfully and quietly ) done it (and I'M not spilling the beans as to whom), without advocating it as a DIY fix. Yes there are reasons to open it, and there is the great danger of gluing other parts of the clutch assembly into a solid mass.

A shorter piece of brass wouldn't reinforce the split under the button exactly where it is needed. A shorter piece under just the button could be used to avoid enlarging the idler B hole, but there's plenty of material where the hole is slightly enlarged.

 

[PacificStereo]

This is great stuff, Mark! Kudos, and very well-done.

 

[markthefixer]

Nice job ,thank you . How about the auto stop. I have notice that some of my decks take longer for the auto stop to engage and seem to struggle. I'm just not sure how it works . thanks

That's a subject for it's own thread (later), plus you don't say (confirm) which models are doing this. The loss of tape movement sensors are radically different between model series. I'm specifically addressing only the 8282 , 9191 and 1000.

8282 rsx-040
9191 rsx-035
1000 rsx-042

are mechanically actuated switch contacts, on the 9191 the rsx-035 opens and closes twice per rotation of the input shaft. Resistance and backlash is felt that implies an oval cam pushing against parallel leaf contacts.

Other models have opto-interruptors with "fan" disks or blades.

 

[Schanz]

Wow. Had to read through this slowly twice. I think I get it now. My non-working 9191 is arriving today. I'm praying that the roller and belts are all it needs. At least I can identify the problem now. Many thanks.

 

[Eagle1]

Fantastic write up and explanation Mark. That's exactly what my 9191 clutch assy looked like when I took it apart and I'm sure the 8282 is cracked as well. Now it's all very clear what is causing the binding problem. Thanks again for the great info and pics. My two clutch assy's should be on their way to you next week. Just waited to hear the word that you got the tooling. :thmbsp:

 

[DENNYDOG]

Excellent writeup Mark. I have a feeling you will be quite popular after this.

 

[Hokieman]

:thmbsp: Well done.

 

[Bigkahuna]

Nice job

Mark,
Nice job looks pretty intense.. Do you have a figure in mind if I were to send one of these to you?

 

[markthefixer]

PM sent. saying more in a thread will turn it into an ad and get it deleted.

 

[Schanz]

How's this clutch?

Disassembled the tape mechanism. How's this clutch look? Seems OK to me. Spins OK but not real lose.

 

[Eagle1]

Disassembled the tape mechanism. How's this clutch look? Seems OK to me. Spins OK but not real lose.

Nice Pic, but you can't tell until you the clutch assy apart. It should not bind/touch against the elbow bracket.

 

[Schanz]

I was hoping that wasn't the case.

 

[PacificStereo]

If your deck fast-forwards and rewinds correctly (and hasn't been modified to try to overcome a defective clutch assy), then the clutch is fine.

 

[Schanz]

I just took the clutch apart. The little center shaft is indeed cracked.

 

[tarior]

Brilliant!!

 

[shimniok]

Nice. I know where to go when/if my 8282 clutch gives it up.