[sdiy] Yamaha CS-60 issues

[Roman Sowa]

I would try to replace the gates - IC9 and IC10.
And also see what's happening to the voltage at pin 16 of YM26700 when 
you play different octaves.
Entire KBC circuit looks overcomplicated for no aparent reason. Maybe it 
was done on purpose that middle octave is not responding to both 
brilliance pots.

Roman

W dniu 2020-10-02 o 19:06, al spitzley pisze:
> Thanks for the input.
> So I traced the main problem being caused by the GND 2, the GND for the 
> -6.5 and +8.5, not getting to the KBC via the KAS board.
> So now the Brilliance controllers work on all but one of the octaves. I 
> checked the logic on the 3 lines that select the octave and they are 
> working as expected. I checked the resistors around the octave ladder 
> and they are correct. So it seems I do have a partially functioning 
> YM26700. I can't see what else it could be. Just for piece of mind i 
> replaced the shift registers and flip flops. Still no joy.
> A retrofit would be amazing for me and many others. It could save many 
> of the Yamaha CS series in the future. They are ticking time bombs for 
> these beautiful synths. I know Old Crow was working on something similar 
> a couple of years ago, not sure what happened with that project.
> I do not have the design skills for this, but would happily help anybody 
> brave enough to take it on!
> best
> Al
> 
> 
> On Friday, October 2, 2020, 4:25:41 AM PDT, Roman <modular at go2.pl> wrote:
> 
> 
> Plus of course the glissando adder, so this rules out discrete logic 
> design, and here comes small microcontroller.
> 
> Roman
> 
> Dnia 2 października 2020 12:32 Roman Sowa <modular at go2.pl> napisał(a):
> 
>     YM26700 is just a bunch of multiplexers. It selects octave voltages from
>     one external resistor ladder and semitone voltages from another resistor
>     ladder and drives 8 outputs sequentially with Hz/V voltages, all
>     controlled by key assigner.
> 
>     If it goes for $2000 (I saw them on ebay for $600) it's hard to believe
>     noone has ever done a replacement yet.
> 
>     So, who's going to be first offering YM26700 retrofit?
>     Don't look at me, I don't have time for this.
> 
>     Roman
> 
> 
>     W dniu 2020-10-02 o 11:21, Gordonjcp pisze:
> 
>         On Thu, Oct 01, 2020 at 07:48:47PM -0700, TERRY SHULTZ wrote:
> 
>             Hi Al,
> 
>             I spoke with Paul Morte and he indicated that the YM2600 is
>             going for about $2000  USD these days.
> 
> 
>         What does the YM26700 do, and how easily do you think it could
>         be cloned or emulated?
> 
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