Discussion about the Korg PolySix synthesizer

Hi gil,

the SSM* are OK, I checked them. I had a nice day with the oscilloscope
and found out: The output of the signal generator board is already bad.

Then I replaced two opamps 4558 which I suspected to be the problem but
it didn't help. Still 0V out instead if the signal on oszillator 2 (VCO
1 (sic)).

Next suspect was the CMOS switch which I replaced by a similar type. But
Somehow it wasn't similar enough, so I got -9V in the output now, which
is definitely not good.

I'll keep on soldering. ;-)

Best,

   Niels


gil_we schrieb:
> Did you switch SSM2056 and SSM2044 between voices to see if it may 
> lay there ?
> 
> 
> --- In PolySix@yahoogroups.com, Niels Ott <niels.ott@...> wrote:
>> Hello there,
>>
>> my Trident MK2 is defective.
>>
>> Symptom: VCO 1 is defective for one voice.
>>
>> Up to now I was able to found out: Input 1 of IC704 (4x CMOS 
> switch) on
>> KLM-379 doesn't get the VCO signal on voice 7. On all others it 
> does.
>> There are some oddities with op amp IC707 but I'm not yet sure. The
>> schematics and the circuit board design hint to the direction that 
> IC707
>> "feeds" IC704.
>>
>> The IC707 is a 4558, I assume that it is similar in the Polysix.
>>
>> Did anybody of you experience a similar problem? What about 
> replacing
>> the 4558, did this help?
>>
>> Furthermore, some of the 4558s carry a date stamp of 1997 which 
> means
>> they must have been replaced by an earlier owner.
>>
>> Unfortunately there is no shop selling electronic parts in reach so 
> I
>> can't just go for it and try replacing it. Mail order is an option 
> but
>> not for a few ICs...
>>
>> Thank you for commenting.
>>
>> Best,
>>
>>   Niels
>>
> 
> 
> 
> 
> 
> PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6 
> Yahoo! Groups Links
> 
> 
> 
>