Casio PX-150 - some black keys trigger full-velocity note on aftertouch

Synth Repair
1

Hi all. My wife has a PX-150 and, a little while ago, one of the black keys started playing a full-velocity note right on the note release. It was sporadic at first, but became more consistent over time. We could recreate it most reliably by holding down the key very firmly then releasing. The issue continued to grow and now a#, c#, f#, and g# (one octave above middle c) all do it to some extent.

I took the piano apart and moved the contact strip from the bottom octave to the area in question. That lower strip doesn’t get a lot of use so I thought it might be better but the problem continues. The board looks clean and I didn’t see any evidence of damage, corrosion, etc. We’re the original owners and nothing has ever been spilled on it.

I’m thinking that getting new contact pads would address the issue but I’m not sure why only the black keys are being affected (different weight/size of the keys?) and why switching the contact pads didn’t help. If it’s the board, I’m not sure why it would be so sporadic and change over time.

Can someone suggest what might be best to replace to get rid of this issue? My wife doesn’t want to play as the sudden, loud notes make playing Claire de Lune an even more anxiety-provoking experience than usual! :sweat_smile:

Thanks for any help you can provide with this!

2

sounds like a corrosion issue. If changing the rubber strip to another area fixes the issue, then bad rubber.

3

chances are if you look at the base of the flexible pads, you will probably see some shine.
That is basically a grime that needs to be removed from all the contacts with some alcohol. (at least 91%). also the contacts on the board need to be cleaned.
What you are experiencing is a classic example of dirty contacts.
Often there is no rhyme or reason to which keys get affected.
You will be surprised how much grime comes off.
So either you do it or get someone to do it or buy new contact pads…get a complete set.
If you do that, just be sure to clean the board contacts.
Also be aware of the direction the strip faces…there is a right way and a wrong way…so don’t get it backwards! (that is easy to do!)