I have a weird problem with my CASIO keyboard where individual keys work but pressing a certain combination of different keys ends up with giving no sound from the keyboard

[Reymond Drill]

As the pretty long title says. On top of that, even some individual keys are not working either and that might just be a problem with the keys not making proper contact with the strip that lets the casio knows a note is being pressed maybe?? I'm completely not sure for the other problem though. Any help would be appreciated.

[AndrewL]

My wild guess is that pressing several keys kind of bends the keybed and probably it's not doing proper pressing of the sensors, especially if it's on a stand... although it's still weird. Does placing the keyboards on a solid surface like a table change its behavior at all?

[Reymond Drill]

It has that problem regardless of the surface it is situated on

[Brad Saucier]

How old is it?  

[Jokeyman123]

are you saying random chords will cut off all the other sounds? Is there a specific octsve or octaves that cause this? IMO, after having torn down my PX560 a few times-including getting the entire key assembly out and about on its own, there is no particular contact strip in there except for the IC boards, so I am diagnosing practically blind but my best guesses...

 

1) Could be as simple as the main key assembly contact ribbon coming a bit loose, shifting in its socket. This is a pretty frail strip and although it should be in its socket pretty tight, it could shift out enough to cause this rather odd malfunction. it is a ribbon connection, not a socket.

 

2) Since individual notes seem fine, but more than that causes a disconnect-some of the screws that mount the keys to the top part of the keyframe may have worked loose-this would cause some of the keys to lose fulcrum action and not sit properly on the rubber boots underneath-one key might work OK, but if several have come loose-and it can happen simply from playing-the weighted action needs to sit pretty secure in its frame-pressing a few keys might cause a complete disconnect-since the IC boards are connected in serial-if enough keys are not making contact at once-might shut down the entire key assembly since the scanning chip for the keys could be completely thrown off.

 

3) The IC boards under the keys-also may have come loose, in some sections and not others-again from repetitive playing-and this could cause a problem like this.

 

Sounds like this would need a complete teardown to physically inspect what I am guessing at. And you might do all this inspecting yourself and discover it is a deeper electronic problem-such as a bad mainboard since that is the only component I remember that is directly connected to the key assembly.

 

If this is under warranty, I would let Casio tech wrestle with this. Even if it isn't under warranty, its still worth repairing IMO. I'll be bringing mine in soon as the audio system for the speakers went south-very odd as everything else has always worked perfectly. But that's another horror story-as I disassembled mine for the 4th time!(!!!!) and found no easy solution-everything looked perfectly intact inside so to repair it goes. And mine is at least 4 years old now or I think 5.

 

[Reymond Drill]

For one, it's actually quite old, more than 7 years old I think. And also to clarify for Jokeyman123, pressing individual keys is fine but if I decide to press a key with another key, certain keys just don't make sound even if they did when I pressed them individually. 

Also, whenever I press any random key, it seems only a few certain keys don't work with it, but when I press another key, a different combination of keys don't work with it. For example, if I press a C note in one octave, A B C and E might not work with it, but if I press A, D E B and G might not work with that key