Discussion about the Korg PolySix synthesizer

Hi! First post, but let's just get right to it.

I bought a P6 11 years ago, and it hasn't been used much, but  a recent interest in going hardware made me dig it out again. I'm getting it MIDIfied, so I'm giving it a thorough look to get everything in top shape. I bought it with the battery fix already done, and the PCB hasn't been ravaged by corrosion, but the MG Mod switch will only work on the VCO and the VCF.

A search yielded similar issues but little and incomplete information regarding a fix for this, which leads to my question: is there an easy fix for this and have anyone successfully sorted it?

Hi,

Check to make sure that the signal entering IC1 pin 3 leaves on pin4 when in
VCA mode. If not (and I suspect not) check the switching action of IC1 on
pin 5. If not working check the quarter comparator in IC3 at pin 5. Finally
check the latch at IC 29. You can test most of the different logic states
using a scope or, even better, a logic probe. This¹ll all be CMOS ons and
offs. Tip: you can get comparative reading from the VCO mod circuit which
follows the same lines, but on a different switching channel. (Please study
the 367 schematic first!) Although you have had the 367 repaired I seriously
suggest you start off doing a cold DC continuity check between the tracks I
have mentioned. I¹d favour a break in the print over silicon in this case!

Good luck and tell us all how you get on...

Thanks,
Andy


On 01/03/2010 20:24, "djvlr" <xheigrestadx@gmail.com> wrote:

>  
>  
>  
>    
> 
> Hi! First post, but let's just get right to it.
> 
> I bought a P6 11 years ago, and it hasn't been used much, but  a recent
> interest in going hardware made me dig it out again. I'm getting it MIDIfied,
> so I'm giving it a thorough look to get everything in top shape. I bought it
> with the battery fix already done, and the PCB hasn't been ravaged by
> corrosion, but the MG Mod switch will only work on the VCO and the VCF.
> 
> A search yielded similar issues but little and incomplete information
> regarding a fix for this, which leads to my question: is there an easy fix for
> this and have anyone successfully sorted it?
> 
>  
>    
> 
> 



[Non-text portions of this message have been removed]

Issue resolved. 

I had to go open it up to swap some of the tact-switches and "middle-pieces" , and decided to look into this issue again. 

I found a similar thread about a broken trace under the test point near CN-03 - I thought I'd give it a go and tested for connectivity there, and yep there was a broken trace. Soldered a wire to reconnect the points, fired it up and now the VCA can be modulated. 

I'm pleased.

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:

>
> Hi,
> 
> Check to make sure that the signal entering IC1 pin 3 leaves on pin4 when in
> VCA mode. If not (and I suspect not) check the switching action of IC1 on
> pin 5. If not working check the quarter comparator in IC3 at pin 5. Finally
> check the latch at IC 29. You can test most of the different logic states
> using a scope or, even better, a logic probe. This¹ll all be CMOS ons and
> offs. Tip: you can get comparative reading from the VCO mod circuit which
> follows the same lines, but on a different switching channel. (Please study
> the 367 schematic first!) Although you have had the 367 repaired I seriously
> suggest you start off doing a cold DC continuity check between the tracks I
> have mentioned. I¹d favour a break in the print over silicon in this case!
> 
> Good luck and tell us all how you get on...
> 
> Thanks,
> Andy
> 
> 
> On 01/03/2010 20:24, "djvlr" <xheigrestadx@...> wrote:
> 
> >  
> >  
> >  
> >    
> > 
> > Hi! First post, but let's just get right to it.
> > 
> > I bought a P6 11 years ago, and it hasn't been used much, but  a recent
> > interest in going hardware made me dig it out again. I'm getting it MIDIfied,
> > so I'm giving it a thorough look to get everything in top shape. I bought it
> > with the battery fix already done, and the PCB hasn't been ravaged by
> > corrosion, but the MG Mod switch will only work on the VCO and the VCF.
> > 
> > A search yielded similar issues but little and incomplete information
> > regarding a fix for this, which leads to my question: is there an easy fix for
> > this and have anyone successfully sorted it?
> > 
> >  
> >    
> > 
> > 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

Hi,

As ever your persistence was rewarded! Good job and thanks for letting the
group know. 

Cheers,
Andy


On 23/01/2011 18:45, "djvlr" <xheigrestadx@gmail.com> wrote:

>  
>  
>  
>    
> 
> Issue resolved. 
> 
> I had to go open it up to swap some of the tact-switches and "middle-pieces" ,
> and decided to look into this issue again.
> 
> I found a similar thread about a broken trace under the test point near CN-03
> - I thought I'd give it a go and tested for connectivity there, and yep there
> was a broken trace. Soldered a wire to reconnect the points, fired it up and
> now the VCA can be modulated.
> 
> I'm pleased.
> 



[Non-text portions of this message have been removed]