Discussion about the Korg PolySix synthesizer

I did find -13v at Ic18  .
I changed it with a working one ( I tested it before and have -3 v).
It partially solved the issue . Thanks 
I can reach a C.But still I can tune the low or the highBut not together (from the same voice , I can t have c2 and c6 together bra cause the trim high don't allow to go till c6 from the key c6)  ... so I can tune right on an octave but not at the whole keyboard ...+ i remarked that VR2 ( tune high , right ?) has no effect when I turn it. Can the issue come from there ?
Thanks 


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Le mercredi, septembre 20, 2017, 9:08 PM, mr gham mrgham@yahoo.com [PolySix] <PolySix@yahoogroups.com> a écrit :

    

Thanks I ll check that 

    On Wednesday, September 20, 2017 5:53 PM, "Tony McAdam swamp.gigs@googlemail.com [PolySix]" <PolySix@yahoogroups.com> wrote:
 

     Hi - here's how to check the opto... http://huebnerie.de/blog/2013/07/polysix-photocoupler-myths/

"This leads to an eady way to check whether a tuning problem is related to the photocoupler circuit at all: measure the voltage on pin 7 of IC18. Within regulation it should be somewhat between -2 and -6 volts, -3 are more normal.
When the loop breaks open due to failure of the photocoupler or related parts, it will be stuck on the maximum negative output, something around -13 volts. There must always be a small current through the LED, otherwise the loop does not work and the TUNE HIGH preset has no effect!"

For the older daughterboard version it's pin 6 on IC18 as it's an 071 instead of an 072....

On Wed, Sep 20, 2017 at 3:44 PM, mr gham mrgham@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:

     Hi Tony,
This is a new 366


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Le mercredi, septembre 20, 2017, 4:28 PM, Tony McAdam swamp.gigs@googlemail.com [PolySix] <PolySix@yahoogroups.com> a écrit :
    What version 366 board is it ? Sounds like an optocoupler problem...