Yamaha CS80

from my tech


Hi
  I'm working on a CS80 for the first time in years. I am looking at the 
after touch areas of this one, and after replacing and socketing all 
chips on the TKC & TSB bds and I still have 4 notes (C', f' , f#, and 
G') through all octaves not responding to after touch.
	As I scope the A,B,C lines, I notice pin 9 on all 4051's is inactive, 
regardless of playing multiple keys, or activating after touch. Pins 10 
& 11, become active under certain states. I have gone back through the 
immediately obvious circuitry and even re -replaced the chips involved, 
to no avail.
	 My question is, if you probe a working CS80 at pin 9 of any of the 
4051's, is the line active? If not, do you have a viable approach to 
this issue ?


thanks


Stephen Teller
Stephen Teller Music
805/480-9614
s.teller@...
www.stephentellermusic.com

Educated guess: replace IC4 & IC5 on the KAS board.  It sounds like a 
note encoder line (_N3, to be exact) is not operating correctly.

Crow
/**/

On Sun, 3 Apr 2005, STEPHEN TELLER wrote:

> 	As I scope the A,B,C lines, I notice pin 9 on all 4051's is inactive, 
> regardless of playing multiple keys, or activating after touch. Pins 10 
> & 11, become active under certain states. I have gone back through the 
> immediately obvious circuitry and even re -replaced the chips involved, 
> to no avail.
> 	 My question is, if you probe a working CS80 at pin 9 of any of the 
> 4051's, is the line active? If not, do you have a viable approach to 
> this issue ?