Hard to Turn Tuning Knob (CR-220)

captouch

Addicted Member
Hi All,

I have a very hard to turn tuning knob on a Yamaha CR-220 receiver. I have it open and applied lube to all the plastic pulleys as well as the rotation points on the wheel of the tuner (brown wheel immediately outside of tuning mechanism). Seems that at least part of the problem is the external knob itself being very hard to turn, though the interior brown wheel is also pretty stiff if I manually turn it. Took some half-hearted attempts to pry the exterior tuning knob off with two spoons to lube around the knob, but not sure if something more fundamental is going on. I know it's not the best idea, but since I couldn't get the knob off, I sprayed some WD-40 (vs lube) where I couldn't reach near exterior knob and immediately behind faceplate, but didn't help much.

To be clear, after doing abovem the exterior knob will turn and span whole frequency range, it's just really, really much harder to turn than it should be.

Anyone have any suggestions?
 
The shaft of the tuning knob between the exterior knob and the flywheel needs to be disassemble cleaned. the chassis bushings thoroughly cleaned and , relubed with white lithium grease and reassembled. It will spin like a top after that.:thmbsp: I use mineral spirits to clean the old solidified grease off the metal parts and then apply a thin coating of fresh grease.
 
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half-hearted attempts to pry the exterior tuning knob off with two spoons

May have 1 or 2 set screws at the base of the tuning knob.Which is located between the front bezel and the chassis. They can be accessed from the side of the unit.
 
The shaft of the tuning knob between the exterior knob and the flywheel needs to be disassemble cleaned. the chassis bushings thoroughly cleaned and , relubed with white lithium grease and reassembled. It will spin like a top after that.:thmbsp: I use mineral spirits to clean the old solidified grease off the metal parts and then apply a thin coating of fresh grease.

Hi Avionic,

There were indeed two set screws to get the knob off - thanks, saved me from destructive and frustrating pulling. :thmbsp:

What I see from the outside after I pull off the knob is below. I see there's a thin nut I can unscrew. Is the shaft turning at this point the part that needs to be cleaned/relubed? (Somehow, I doubt that I'd be lucky and it'd be this simple. . .)

P1050410_800.jpg


Or, if I look inside, I see this bigger metallic cylinder that the tuning string is wrapped 3x around. Once I remove the nut in the picture above, do I need to pull this entire assembly inside, unstring the tuning string, and take apart and clean/relube this big metallic cylinder (perhaps this is the bushing?) If so, once I get it out, is it pretty intuitive?

P1050408_800.jpg


Finally, when I manually turn the brown wheel (flywheel?) in the picture below, it takes some effort as well (doesn't turn easily) - not sure if this is because the above parts need re-lubing, or it itself also needs relubing. If it's difficult to turn, do I also need to take this apart and relube it separately?

P1050412_800.jpg


I'm trying to figure out how big a job this is for a first-timer. I actually don't listen to the radio a lot, but was more wanting this to be fully operational because it would make me feel better. But if it's a fairly extensive job that I stand a chance of screwing up, I'm better of leaving it as is.

Welcome any additional thoughts and inputs. Thanks again.
 
First photo--The center shaft will need to be removed from the bulkhead threaded bushing.See if you can pull the flywheel off the other end without having to disturb the dialcord winds. I use masking tape to secure dialcord to there various pullys. Those two phillips setscrews at the flywheel end, securing the brass collar will need to be loosened up.That should allow the flywheel to slide off the back side.Once the flywheel is off the shaft ,you should be able to pull the center shaft out of the bulkhead bushing.Most likely will be a little stubborn coming out.
The old lubricant now has the consistancy of old sticky corn syrup.
 
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How goes the battle?:D

Thanks for asking. Honestly, I'm still trying to visualize exactly what I need to do, step by step, based on your earlier responses. Problem is I'm not familiar with what are single assemblies that don't come apart and what are individual pieces.

For example, when I loosen the two Philips set screws, do I need to completely remove the brass collar and the dialcord winds around the shaft, then slide the flywheel off the shaft, then pull the shaft out the front and lube that?

Or is the flywheel, assembly somewhat larger and perhaps the flywheel comes off with the dial cord winds intact? My biggest hesitation on this particular job is the dial cord - it's taut enough that if I make a mess enough out of it and can't string it back up properly, I'm defeating the purpose of making the tuning wheel easier to turn.
 
For example, when I loosen the two Philips set screws, do I need to completely remove the brass collar and the dialcord winds around the shaft, then slide the flywheel off the shaft, then pull the shaft out the front and lube that?
Most likely..
To do it right the shaft needs to be removed and thoroughly cleansed of the sticky crap from both, inside the bushing and the center shaft.Then lightly relubed and reassembled.
Restringing dialcord can be a daunting chore.I can understand not wanting to risk unstringing it.
The service manuals have a re-stringing diagram. I take plenty of photos,notes and try to minimize the chance of key areas from unwrapping ie. Flywheel and the tuning cap pulley.
 
I hope I'm not intruding...thought I'd share my related newbie experiences with dial string.

I wrapped the tuning cap pully with masking tape to keep the string in position. Seemed to help me at least to have a level of comfort before I freed the string from it's other wheels.

I have also inadvertantly rewound the tuning shaft backwards which caused the string to miss-align with the adjacent wheel. Make sure you wind the string the correct direction and correct number of rotations.

Lastly, I once set my CR-2020 tuning knob too deep onto it's shaft. Had to reopen the case and loosen the set screws for to pull the knob out just a tiny bit. It was rubbing against the subpanel.
 
Not intruding at all - I appreciate the input. I probably will tackle it this week or next. No guts, no glory, right? Though I will probably make sure it receives FM fine so I don't make it nice and easy to turn only to fine the tuner has other issues.

Need to get some white lithium grease as well.

Now, re-capping is something I'll need more courage to take on. I wonder what % of vintage collectors do re-capping themselves - I'm personally pretty intimidated by it.

Btw, I hear the 2020 is a nice unit. Maybe someday if I can pick up one cheaply enough!
 
Well, I can't say exactly what resolved it, but when I was trying to unscrew the two screws on the brass collar so I could remove the flywheel and shaft, the shaft started moving very smoothly again and now glides like a champ.

Strange, but in a good way that simplified my effort to fix this. About to listen to this for awhile this afternoon. Thanks for your help guys!
 
I wanted to revive a dead thread to thank Avionic for his guidance on this issue… I bought a CR-420 a few weeks back and that tuner was literally a workout. Once I understood how to pull that pin assembly out (literally undo the two internal clamp screws and pull that sucker out using the tuning knob as your clamp and base), I used the white lithium grease and felt like a kid who just built his first erector set.
 
I wanted to revive a dead thread to thank Avionic for his guidance on this issue… I bought a CR-420 a few weeks back and that tuner was literally a workout. Once I understood how to pull that pin assembly out (literally undo the two internal clamp screws and pull that sucker out using the tuning knob as your clamp and base), I used the white lithium grease and felt like a kid who just built his first erector set.
:thumbsup:
 
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