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Yamaha A-1 volume knob repair disc

H

Hifibythekg

Super Member
Hello all.
The Yamaha A-1 has an aesthetically beautiful stereo volume knob. But, the flat disc section that controls the …. channel has worn lose in the centre.

  • What’s the best cure?
  • Blob of glue?
  • Some substance to ‘pack’ the interior so that it’s a tighter fit?
(Both of the above seem like a ‘bodge’ repair.)

  • Or can the plug in the middle of the disc be extracted and replaced? If so what’s the specific part/brand/model number required?
  • 0E67E1C4-FFC6-4131-B600-D5B98373358B.jpeg 5C573109-6E8B-4958-AA56-83E06872946C.jpeg

  • 5D8CCBCC-979D-40D7-A8DE-47AC627ADEBF.jpeg
 
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Put some vaseline on the shaft and inside flat area of inner knob as a release agent for the up coming Epoxy.
Then put some epoxy putty in the hole, just enough to be able to push the disc onto the shaft with minimal overflow .

Allow to dry. Then see if you can pull off the disc. clean up any putty that oozed out with a Xacto blade. also no clean up the vaseline with denatured alcohol.

the disc should not have the lines in it and work well.

Athanasios
 
Apologies but haven’t yet tried it, other tasks have demanded attention.
Also wondered whether this worn plastic ‘insert’ is actually a very standard component that could be found in the centre of millions of control knobs and might only require a little bit of trimming/customisation to fit perfectly. Just a question of knowing the name / spec of the part.
I bet @avionic has come across this issue before, wonder if I should ask him?
; )
 
What is the diameter of the shaft? Usually they are 6-8 mm .

These may work .

https://www.divapor.com/spares/bath...-adapter-20-spline-76mm-to-24-spline-95mm.php

20-to-24-Spline-Cartridge-Spline-Adapter-TN2.jpg
Tap-Cartridge-Spline-Adapter-TN2.jpg


https://www.divapor.com/spares/bath...-adapter-76mm-20-spline-to-92mm-21-spline.php

482D566-Spline-Adapter-TN2.jpg
Spline-Adapter-TN2.jpg


More selections here

https://www.divapor.com/spares/bathrooms/cartridge-adapters/cartridge-adapters.php

Athanasios
 
Last edited:
Wow, good lateral thinking… a bathroom spares supplier. I couldn’t see one in the appropriate size but thanks for trying.
The A-1 insert is:
interior diameter 6mm
outer diameter 9mm.
 
Also, with this search term “splined shaft pot spline insert 6mm” on Google’s ‘Images’ filter, lots of possibilities show up.
Although, it may well be that your original suggestion will work best, or perfectly well!
 
Just thinking that a replacement insert could be printed. Looking at mine the insert is just a friction fit. You should be able to remove the old plastic and push a new one in.
 
Yes. Although in scanning my original it would be scanning a worn/damaged component which would then be recreated..
But there's probably a workaround going down this route, thanks.
 
Thanks. Yet to try your original putty suggestion. Unbelievably after replacing the speaker relay the amp has just cut out again at medium volume and having had several sessions when it played stunningly beautifully for hours and hours.
Just started a new thread.
 
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