KN800 weird settings to fix : keys making the same note

Hello dear friends,

I don't know how, but the kids played with my Technics KN800 and now there is a weird setting I can't find how to fix.
I have scrupulously made the following resets, but the problem still persists : I have reset the settings according to the service manual, page I-5 ("initial settings" by pressing the 3 pads "1" "2" et "3" and then I started again the keyboard), the problem persists.
I also did a reset of the initial settings on the "musical director"... It asked "are you sure?" and I selected YES. And the problem persists.

Here is the problem :
- The C and D keys do the exact same note.
- The C# and the D# keys do the exact same note.
- The E and the F# keys do the exact same note.
- The F and the G keys do the exact same note.
- The G# and the A# keys do the exact same note.
- The A and the B keys do the exact same note.

This problem repeats on all the octaves on the keyboard.
Do you know, dear friends, how I could restore the notes in order to put everything back to normal ?


Bien à vous,
Lionel, from France