Discussion about the Korg PolySix synthesizer

Hello

I may have diagnosed and fixed the problem. I had unscrewed the keyboard 
and pulled it away from the PCB board, so that the two were not close. 
Then the P6 behaved as it should for a long time. I could play the 
(loose) keyboard, and I had the arpeggiator running for an hour. 
Everything acted normal.
Then I put the keyboard back in place and started to play some more, and 
surely, withing a minut or two it started to behave badly again.
This made me suspect that it is the proximity of the keyboard to the PCB 
board that really is the problem. I then put a piece of paper in between 
keyboard and PCB board, and now the P6 behaved normally again. I also 
noticed that the paper was actually pinched between keyboard and PCB 
board. So something on the keyboard is touching and possibly shorting 
something on the PCB board. Probably the new optocoupler which is right 
there under the keyboard touches a screw or something.
So.... I have put a piece of isolation in there, and added two spacers 
to the rear keyboard fastening screws, to add a little distance, and 
this seems to have cured the problem. I guess the problem is that the 
VTL5Cxx is taller than the original optocouplers, and his brings it 
close to the keyboards. So beware when you fix the scaling problem, that 
the opto is mounted with sufficient distance.

Best

/frank

On 11/18/2013 11:16 PM, Johannes Hausensteiner wrote:
>
> OK, so the keys that do not work are F#1, G1, D2, D#2, A#2, B2, F#3, G3,
> D4, D#4, A#4, B4, F#5, and G5, correct?
> When starting the arpeggiator (besides playing wrong notes) does it
> light the small voice-LEDs on KLM-366?
> When connecting a footswitch to the CHORD MEM footswitch jack, does the
> CHORD MEM button LED work as expected (can be switched on and off by
> footswitch)? Note: if you do not have a footswitch you can you a normal
> phone cable and short the tip to the sleeve on the far end connector
> with a paperclip or similar for a test.
> And the HOLD button works?
>
> From the noworking keys I would say the lines P16 and P17 are not
> working correctly. But the buttons and the VCO control voltage should
> work OK...
>
> Try: disconnect CN12 from KLM-366 (this goes to KLM-371). Are the notes
> in tune?
>
> Johannes
>
> On 18.11.2013 19:15, Frank Carvalho wrote:
> >
> >
> > Poly/Chord/Uni do not seem to have any effect, and the LEDs don't 
> come on.
> > Hold is on when the synth is turned on, but can be turned off and on.
> > Hold now lights up.
> > If the keys are numbered repeatedly with 1 to 8, beginning with the
> > lowest key, then it is every number 6 and 7 that is off.
> > The arpeggiator sends repeated trig signals, but as the same note sounds
> > every time, I cannot hear anything but the repetition. Actually the
> > sound is much like a detuned unison mode.
> >
> > And, yes, I have an ancient Philips oscilloscope, if necessary.
> >
> > I certainly hope I can fix it. I love this synth.
> >
> > Oh, before anyone asks, I did the battery mod long ago, before any leaks
> > occurred.
> >
> > Thanks
> >
> > /Frank
> >
> > On 11/18/2013 09:09 AM, Johannes Hausensteiner wrote:
> >>
> >> The issue is related to the KLM-366 Key Assigner CPU circuitry. 
> Probably
> >> two of the I/O lines are dead (remember, it is an 8bit CPU).
> >> Which keys do work and which don't?
> >> Do the key assigner buttons (POLY/UNI/CHORD/HOLD/ARP) work?
> >> Does the arpeggiator don anything?
> >>
> >> Do you have access to an oscilloscope?
> >>
> >> This surely can be fixed!
> >>
> >> Johannes
> >>
> >
> >
> >
>
>