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Yamaha C-80 lost sound switching inputs

ghankstef said:
Well here they are after cleaning don't see anything suspect
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Make sure you clean the shaft at where it connects to the housing. There’s a metal contact ring of sorts (see below) that provides grounding/support(?) at that junction and if dirty/damaged, you get potential malfunction in terms of sound balance (L/R), audio cut-off, audio quality, etc.

Also make sure turning the shaft has absolutely no rotational as well as non-rotational play. Mine did and caused audio disconnects, volume reduction, and cracking noise. I had to finally change the housing.

F35F4878-6BA2-4EDA-8D82-83E7271905F0.jpeg
 
Sparkplug said:
Make sure you clean the shaft at where it connects to the housing. There’s a metal contact ring of sorts (see below) that provides grounding/support(?) at that junction and if dirty/damaged, you get potential malfunction in terms of sound balance (L/R), audio cut-off, audio quality, etc.

Also make sure turning the shaft has absolutely no rotational as well as non-rotational play. Mine did and caused audio disconnects, volume reduction, and cracking noise. I had to finally change the housing.

View attachment 3317757
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Ok will do. Getting it back together with no play seems daunting
 
ghankstef said:
Ok will do. Getting it back together with no play seems daunting
Click to expand...
Putting it back together will not cause any free play, I was referring to any possible damages up until now. If there’s no free play, it means the shaft is healthy and just needs cleaning. Also don’t forget to use fader lube on the wafers (lightly) after cleaning or you’ll get noise and cracks when you turn the volume because of the little combs scratching along the resistive surface.
 
Sparkplug said:
Putting it back together will not cause any free play, I was referring to any possible damages up until now. If there’s no free play, it means the shaft is healthy and just needs cleaning. Also don’t forget to use fader lube on the wafers (lightly) after cleaning or you’ll get noise and cracks when you turn the volume because of the little combs scratching along the resistive surface.
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Thanks I have some deoxit f100 and the wafers will get a single drop and spread out with a q tip . Should I lubricate the shaft? Seems like I should
 
Reassembly begins...

Before this step I forgot to take pictures... Whoops

Not sure which piece is next will have to experiment
 

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Did your shaft get the ultra sonic bath too? Since I don't have an ultrasonic cleaner jones I use PB blaster between the outer & inner shafts. The only liquid I prefer more than beer.

Esoteric Redneckisms
 
Soundscape said:
Did your shaft get the ultra sonic bath too? Since I don't have an ultrasonic cleaner jones I use PB blaster between the outer & inner shafts. The only liquid I prefer more than beer.

Esoteric Redneckisms
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It did go in the utrasonic bath but when it was all together I've cleaned it off with rubbing alcohol and applied a fresh application of fader grease
 
Nah a better tech would have this working right now. Detailed potentiometer restoration is new to me.

I've recreated the scene of the crime
 

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Ok putting it partially back together I'm not getting good readings from the loudness part of the pot which if i understand correctly is closest to the loudness knob. I think I see why. In the image the 2nd wafer for the loudness part of the pot is just worn and the contact with the legs is just gone. The first wafer looks ok and is the last one in the pot.

I think I could order this pot and pull the wafers out of it as long as it's the same size.
 

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ghankstef said:
Ok putting it partially back together I'm not getting good readings from the loudness part of the pot which if i understand correctly is closest to the loudness knob. I think I see why. In the image the 2nd wafer for the loudness part of the pot is just worn and the contact with the legs is just gone. The first wafer looks ok and is the last one in the pot.

I think I could order this pot and pull the wafers out of it as long as it's the same size.
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That’s just a guess, may or may not be the problem. Ordering Alps pots from Mouser, others, is possible but make sure you get the same audio taper B, A, etc. which is usually specified in the schematic.

The pot in the link above is A-curve, and so is the one in the loudness pot in C-80. However, the two in the picture above look somewhat physically different, don’t know if that’ll be an issue.

Edit: One of the wafers in the posted photo (Left) doesn’t seem to have the ‘Y‘ shaped connector/sweeper.
 
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Sparkplug said:
That’s just a guess, may or may not be the problem. Ordering Alps pots from Mouser, others, is possible but make sure you get the same audio taper B, A, etc. which is usually specified in the schematic.

The pot in the link above is A-curve, and so is the one in the loudness pot in C-80. However, the two in the picture above look somewhat physically different, don’t know if that’ll be an issue.

Edit: One of the wafers in the posted photo (Left) doesn’t seem to have the ‘Y‘ shaped connector/sweeper.
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They are from different parts of the pot. The one on the left is from the last gang 53k and the right is for loudness 50ka . Looking at the one on the right I have put my ohm meter on it and I can't get good readings.
 
ghankstef said:
They are from different parts of the pot. The one on the left is from the last gang 53k and the right is for loudness 50ka . Looking at the one on the right I have put my ohm meter on it and I can't get good readings.
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I’d assemble everything and try it once before any further drastic measures. Also, you should measure any resistance through the connected leads only and not directly from the resistive pads themselves … I think you know that already.
 
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