Discussion about the Korg PolySix synthesizer

Hello

Dons analysis is excellent. After your description of pressing the panel 
buttons, I'd say the cause for the stuck note/dead keys problem is a 
corrupted/broken diode either on the panelboard or the keyboard. If you 
look at the service manual page 7 (new board) or page 5 (old board), you 
will see, that the bus P10-P17 is shared between the keyboard matrix and 
the panel board KLM371, but the panel switches are returned to a 
different bus than the keyboard. If a diode in this matrix is letting 
currents pass in the wrong direction unpredictable things may happen.

If you had a battery leaking, then a diode might suffer from it. I had 
it several times, that the glass body of diodes got leaking, because the 
metal of the wire corroded, so a gap between the wire and the glass 
appeared and humid air could reach the inner of the diode, which again 
causes the diodematerial to change its characteristics.

Unfortunately the service manual doe not contain a schematic of the 
keyboard, so we cant tell which port line this is.

Florian


On 20.04.18 03:33 , jhatzia@gmail.com [PolySix] wrote:
>
> Thank you Don- you really nailed describing my situation. I'm working 
> on it again now. And was trying to reply to your comment to get a new 
> description on the hanging note but it started working again..?
>
> After leaving the synth on for a while I couldn't even get Chord Mem 
> or Hold buttons to react. After cycling the power they reacted again 
> but had hanging notes.. I was then pressing all the key assign buttons 
> and after some clicks it started behaving properly... Now all those 
> dead notes are playing fine (except the last G, A & A# are still very 
> dead).. Very odd. I wouldn't be surprised if it happens again. I'm 
> still unsure where a fault like that would be found in the circuit.
>
> Well- I still have to install about 3 new button cap holders and clean 
> the volume pot, so I would be surprised if the issue arises again, if 
> it does I'll make sure to update this thread.
>
>
>
>