Discussion about the Korg PolySix synthesizer

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
> 
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