Archive of the former Yahoo!Groups mailing list: Yamaha CS80

I'm not sure. It doesn't work. I'm hunting for some sort of theory
or explanation that will get me out of this pickle. There's a smaller
resistance through the switches on the new switching IC's too; maybe
that is also causing problems. I think what I'm going to do is find a
chip broker and replace all of the new TI IC's with the original
Toshiba IC's - TCXXXXP.

Before I replaced all of the chips, I didn't really have any big
problems with the exception of the square wave function not working on
Oscillator bank II when more than one key is engaged - probably a
logic problem. One voice rang really loud because of initial
aftertouch in both banks too - I also assumed that that was a logic
problem. I did notice that lots of things were way out of tolerance
in the calibration manual but didn't take note because I assumed that
I had massive 4000 series failures. Working backwards, it seems that
the 4000 series IC's were working. My square wave problem is still there.

Who knows what is causing so many problems. I'm glad I didn't buy the
chip sockets with the internal cap. Now I can just switch out the
IC's and go backwards. I'm amazed that my CS80 could be so far out of
tolerance. Has anybody else had huge tolerance discrepancies
restoring their CS80's?

In retrospect, I think that this is the best way to restore these things:

1.) Recap Power Supply without powering up or calibrating.

2.) Power Up PSU with Remote sense wires jumpered and check with a
load. if PSU checks out ok, connect it to the rest of the unit.
Inventory functions of the unit if PSU is within reasonable tolerance
with the CS80 load. Correct any recap mistakes if found. Do not
calibrate PSU.

3.) Recap the rest of the unit.

4.) Inventory Functions and correct any recap mistakes if found.

5.) Walk through all calibration measurements without calibrating and
take note of everything.

6.) By now, it might be prudent to calibrate, check for contunity, or
replace IC's. Use good judgment and try not to stress the cables.