Yamaha CLP-635 key issues

Hello, I’m having some issues with an entire octave of keys on my keyboard. Some of them sound out with maximum volume even when I play them gently, while others will stick to the bottom, not resetting to their normal position when I press them down. They also feel incredibly stiff, and I have to play with more force to get a sound. What parts do I need to replace?

Thanks for any help :slight_smile:

Edit: also, the keys always make this incredibly loud clicking sound that drives me insane, it’s louder than the piano itself…

Sounds to me like that keyboard needs an overhaul. You could order a number of parts to have on hand, but I would open it up and make a list based on observation rather than ordering parts I might not need.

Maximum volume regardless of velocity could a problem with a contact strip or contact board. If there’s not a short there, you might be looking at something in the decoding circuitry on the main board. Do NOT use a solvent of any kind to clean the rubber contact strips - that includes DeoxIt.

There are 8 different hammers based on white/black keys and which octave they are in. My guess is that some of those are either broken, old grease, or a key return flat spring is broken or out of place.

Is the clicking sound mechanical? That could be a sign that one or both of the two cushions are worn out.

Sorry to be so vague. These keybeds are well designed and there’s a number of parts that can go bad. It will be obvious once you open it up. My suspicion is that a hammer has broken and making contact with a contact board.

Thanks for the reply! Your advice isn’t vague at all, in my opinion–it’s pointing me in the right direction. If by mechanical you mean not coming from the speakers, then yes. If I had to take a shot in the dark, then I would say it sounds as though the hammers are striking against something hard, so there may very well be an issue with the cushions.

Now, if I’m looking at a worst-case scenario here, is this a job a layman like me could do after watching some videos/studying up on the tech?

One more thing, when I open up the keyboard, Would I be able to compare the bad section to the good sections to figure out what some of the issues are?

After opening up the keyboard, I found what was causing the clicking sound and the keys not returning. It seems like the adhesive holding the cushion (the one the hammers strike) has loosened up a bit (the hammers appear to be in good condition). A majority of the cushion is loose, and because of that, not only are the hammers sometimes “bypassing” the cushion and hitting something else, but they’re also getting CAUGHT on the cushion. Since the hammers are caught, there’s no way for the key to return to its original position without me manually lifting the key. It’s a good thing I looked into this sooner rather than later, because I reckon that it wouldn’t be too long before the rest of the adhesive holding the cushion decides to un-stick.

I’m half-tempted to just use some superglue to fix the cushion back in its spot. but I’m not sure if that would hold for several years.

As for the maximum volume regardless of velocity issue, I’m not sure what the issue is. I took the keys out of the piano and unscrewed the contact board, but both the board and strips look fine to me. Should there be a visible issue? I could buy a replacement board and a couple strips to see if that fixes the problem.

The cushions are typically fixed with a double-sided tape/adhesive. For small spots, I’ve used a bit of rubber cement. Not sure if that’s ideal, but it seems to hold everything down okay. And it’s still pliable enough that it can be removed later without marring the frame.

The velocity is detected by the system measuring the time between both of the contacts (of that key) on that rubber strip closing on the circuit board. I’m suspecting a short on the one side is making it look like the key is striking at the same time. I’d test it after you reinstall the keys and see if it is somehow related to the issue you’ve been having with the cushion.

I stuck the cushion back where it should be and went ahead and cleaned some parts that might cause issues in the future. I’ve fixed all my original problems, but I may have caused a new one. The sound quality through headphones has decreased–I think it has also decreased when playing through the internal speakers, but I’m not totally sure, as it’s kind of difficult to discern all the nuances of the sound through them, so I’m not sure whether this is a headphone jack issue, or a computer issue. It’s not a major downgrade, but it’s slightly annoying hearing the sound being slightly muffled when playing with good headphones.

I’d like to know your thoughts, but I’m happy with fixing the issues that I originally set out to fix–it plays like new now!

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Never mind, it’s actually just an issue with my headphones.

Oh! So glad you figured it out. I was trying to think what could be causing such an issue, but really didn’t want to be sending you all over the circuit boards.