Discussion about the Korg PolySix synthesizer

I have an old P6 that I'm restoring. I've manged to get every part 
working but the damn thing will not tune. I substituted the voice board 
and CPU board over and still the problem is the same. The power supply 
rails are rock solid. It has been suggested that the boards I have 
fitted (obviously second hand) could be suffering from an 
inherent/common problem and I'm beginning to agree this is possible. 
Basically if I tune C6 as described in the service manual all is well, 
I then adjust VR1 to get C2 into tune but when I do this C6 is now 
pitched at D#6. On checking C0 or C1 it reads B flat (C2 remains in 
tune and C3 is more or less in tune). I have set up several Poly 6's in 
the past and have never come across this problem. When I measure the CV 
with C0-C5 held, the voltages are not exactly 0.5v apart but I can't be 
sure if they are usually precisely 0.5, 1.0, 1.5v etc at the octaves 
are triggered. I've read on the forum about the opto but because the CV 
descrepancy I'm not too convinced at the moment. Any ideas,,please help

Thanks

Hi all again, 

Just to let you know that it was in fact the opto on the oscillator 
board. I have several of these boards with the same problem and this 
has been the same problem on all. Basically it's impossible to tune 
the unit  and the "intonation" is out when you attemp to tune it. 


--- In PolySix@yahoogroups.com, "darke_one666" <darke_one666@y...> 
wrote:
> I have an old P6 that I'm restoring. I've manged to get every part 
> working but the damn thing will not tune. I substituted the voice 
board 
> and CPU board over and still the problem is the same. The power 
supply 
> rails are rock solid. It has been suggested that the boards I have 
> fitted (obviously second hand) could be suffering from an 
> inherent/common problem and I'm beginning to agree this is 
possible. 
> Basically if I tune C6 as described in the service manual all is 
well, 
> I then adjust VR1 to get C2 into tune but when I do this C6 is now 
> pitched at D#6. On checking C0 or C1 it reads B flat (C2 remains 
in 
> tune and C3 is more or less in tune). I have set up several Poly 
6's in 
> the past and have never come across this problem. When I measure 
the CV 
> with C0-C5 held, the voltages are not exactly 0.5v apart but I 
can't be 
> sure if they are usually precisely 0.5, 1.0, 1.5v etc at the 
octaves 
> are triggered. I've read on the forum about the opto but because 
the CV 
> descrepancy I'm not too convinced at the moment. Any ideas,,please 
help
> 
> Thanks