thank you very much for your advice, rhino!
now, i found the failure. fortunately it was just several tracks on the panel pcb that were broken.
i fixed it with some wire, no problem, the jx is like new, again! i´m glad that i didn´t have to change
a mainboard ic.

cheese nucleus

hi! I have a problem with the tone select buttons on my JX-3P. Button 1-8 in the row don´t work, 9-16 are fine. The problem is always the same when i select the different soundbanks or the sound edit modes, the buttons 1-8 are dead. I´ve already checked the switch matrix on the control-panel board. ...