I originally reported a problem w. my CS80 in that the top octave of keys wasn't triggering any sound. I had some good suggestions from various techs and I verified that the actual keybed was sending the correct voltages from all keys.
The testing and debugging centered around the KAS board. After carefully measuring the values for various keypresses up and down the keyboard, I came to the conclusion that the YM26600 was creating and assigning the right codes, but the YM26700 IC was not working properly.
Thanks to the kindness of a listmember, I popped in a replacement YM26700 and now I have the full range of keys again.
The testing and debugging centered around the KAS board. After carefully measuring the values for various keypresses up and down the keyboard, I came to the conclusion that the YM26600 was creating and assigning the right codes, but the YM26700 IC was not working properly.
Thanks to the kindness of a listmember, I popped in a replacement YM26700 and now I have the full range of keys again.