Discussion about the Korg PolySix synthesizer

Hi,

The caps are Cx10 ... where x is the voice number. On the schematics
only voice #7 is drawn in detail, so you can see C710. Maybe it is not
the cap but the accompanying resistor (R739), or the demux (IC8).

This is a great machine. Two really independant VCOs!

Johannes


gil_we wrote:
> 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 have 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 
>>>blowing on 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
>>>
>>>
>>>
>>>
>>
>> 
>> 
> 
> 
>