Discussion about the Korg PolySix synthesizer

Great! My congratulations for the successful troubleshooting!


On 20.11.2013 17:30, Frank Carvalho wrote:
>
>
> 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
>> >>
>> >
>> >
>> >
>>
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