I have a Roland RD-300s. Five keys don't work. The key contacts are not the problem. I have swapped the rubber contact strips but the symptom does not change. The key numbers/notes are: 5/C#, 13/A, 21/F, 29/C#, 37/A. Notice the repetition. It turns out the dead notes are every eight half steps.
Octave Notes
1 5/C#
2 13/A, 21/F
3 29/C#
4 37A
Looking at the shop manual diagram (SK-688) it looks like the actual piano sound waves must be going through the key switches. I see nothing telling the processor what octave is being hit. So the keyboard SK-688s must be physically combining all the octaves sounds??? I am confused. Help!
Anyway, do you have any ideas what to look at?
