Discussion about the Korg PolySix synthesizer

Hi,

I now had a short look at the schematics. It might be quite simple to 
add such a trimmer.
Have a look at the service manual
http://www.florian-anwander.de/korg_polysix/polysix_service_manual.pdf
On the PDF-page 9 you find the bender and the tune potentiometer in the 
lower right quarter of the page close to the vertical dividing lines.  
Tune is VR2 which is connected by R18 (1.8MOhm) to the summing line. You 
may duplicate those two parts: a 50k trimmer between +5V and -5V with 
the center pin connected via a 1 - 2MOhm resistor with to the summing line.
The most easy way should be to solder the trimmer with its two outer 
pins on the solder side of the left panel pcb KLM-369 at the same 
location as the tune potentiometer. The 2MOhm resistor from the center 
pin of the trimmer can be wired "free flying" to the right side of R18.
A mechanically quite likely suitable trimmer should be a Piher "PT 15 NV 
50K" (example: 
https://www.conrad.de/de/trimmer-linear-025-w-50-k-270-piher-pt-15-nv-50k-1-st-432040.html)

Florian

Am 25.04.2017 um 14:23 schrieb t_tangent2003@yahoo.co.uk [PolySix]:
>
> Hi Florian,
>
> The bender itself is set to middle position so that should be fine. I 
> will have a look at schematics and see if I can find any VR and look 
> if that might need adjusting. Thanks for the idea :)
>
> Tim
>

-- 
http://www.florian-anwander.de