Discussion about the Korg PolySix synthesizer

Thanks very much !

The tuning is bad on both VCO1 and VCO2 of that oscillator (although 
it seems more extreme on VCO2).

I uploaded the schematics diagram for the VCO board to the files 
section - what would be the caps to check on that one ?

Thanks again.


--- In PolySix@yahoogroups.com, Johannes Hausensteiner <johau@g...> 
wrote:
>
> Hi,
> 
> I only have the schematics for the MK I; which I do not know whether
> it is similar to the MK II. Which VCO has the problem? Is it VCO-1 
or
> VCO-2 or both? If it is both then hacve a look at the hold 
capacitors 
> after the VCO CV demux IC15 (a 4051) on KLM-301 board.  These are 
the
> caps C25 - C32.
> 
> Good luck,
> 
> Johannes
> 
> 
> gil_we wrote:
> > I've been recovering this one, found in the flea market. Overall 
it 
> > had about 8-9 different faults that I fixed, leaving two problems.
> > 
> > The first is a bad SSM2056 chip which I need to find. The second 
i 
> > probably inherent in the discrete ciruit of the second oscillator.
> > 
> > Upon powering it up, that particular oscillator will be out of 
tune, 
> > till it gets to its max. internal temperature where the tuning of 
> > that VCO is geting more or less - stable.
> > 
> > All other oscillators are immediately in tune, no matter what is 
the 
> > temperatue inside the machine.
> > 
> > I, of course, tried to figure out what the bad component is by 
> > blowing with a straw on each and each of the suspected compnents, 
but 
> > blowingon every component on the circuit of that oscialltor which 
> > seems to be pitch related, seems to effect the pitch.
> > 
> > I also tried to switch transistors between the bad oscillator and 
> > another (working one) but the problem persisted.
> > 
> > Does anyone have any other idea / direction ?
> > 
> > Thanks
> > 
> > 
> > 
> > 
> > 
> > 
> > PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> >
>