Yamaha CS80

Hi all. 

Hoping you're having/had/will have some great holidays.  Don't forget that amazing holiday song featuring tons of CS80 by a certain ex-Beatle.
OK, do forget it. Sorry for even bringing it up.

Anyway, I'm working on a CS80 and found remnants of a mod that had been removed and wondered if anyone knew what it was.  There's a ribbon cable with a wire going to each M board for channel I.  The wire goes to two sky-wired resistors that drive the F1 and F2 pads for controlling the filters' cutoffs.  They are 56k and 26k, which is about the same ratio but half the values (so double the sensitivity) as the resistors from the filter E.G. to the same points.

Any idea what would have driven this and why?  I'm planning to remove all the resistors and wires unless there's some amazing reason to leave them.

 David

Holiday is fine! Soon back to restoring a cs-60 and replacing all 
trimmers with new... phew!

Sounds like it could be an external cv input  for the vcf cutoff, plain 
and simple.  I had a a four voice which had a ribbon cable installed 
with a d-sub for external cv/gate.

Fredrik Segerfalk
www.analogsweden.com
www.segerfalk.com



David skrev 2010-12-29 03:16:
>
> Hi all.
>
> Hoping you're having/had/will have some great holidays. Don't forget 
> that amazing holiday song featuring tons of CS80 by a certain ex-Beatle.
> OK, do forget it. Sorry for even bringing it up.
>
> Anyway, I'm working on a CS80 and found remnants of a mod that had 
> been removed and wondered if anyone knew what it was. There's a ribbon 
> cable with a wire going to each M board for channel I. The wire goes 
> to two sky-wired resistors that drive the F1 and F2 pads for 
> controlling the filters' cutoffs. They are 56k and 26k, which is about 
> the same ratio but half the values (so double the sensitivity) as the 
> resistors from the filter E.G. to the same points.
>
> Any idea what would have driven this and why? I'm planning to remove 
> all the resistors and wires unless there's some amazing reason to 
> leave them.
>
> David
>



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