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Discussion about the Korg PolySix synthesizer

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TIME SENSITIVE REPAIR- Polysix tuning problem question

TIME SENSITIVE REPAIR- Polysix tuning problem question

2011-03-11 by Bernie GREENBERG

I am working on a Korg Polysix with the usual tuning problems.  I replaced the 
photo coupler with a VACtrol and resistor mod and still  unable to tune 
keyboard. The high tuning control, VR2, seems  to do nothing. I have tried 
different resistor values with the VACtrol  mod and still have tuning problems 
with the high end of the scale. TIME  CRITICAL repair and going out of my 
mind!(BTW- no battery  corrosion at all!)KLM367 aligned perfectly, KLM 366 board 
is  new production. PLEASE HELP!!! Thanks in advance for your  time.

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

Re: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem question

2011-03-11 by Andrew Jury

Just a thought.... Check the operation of IC31 (s/h in at pin 3, demux at
pin 2).

You won¹t be able to fix the problem in a blind panic. Just stop, think and
take a deep breath.

Good luck,
Andy

On 11/03/2011 03:26, "Bernie GREENBERG" <ptsaudio@sbcglobal.net> wrote:

>  
>  
>  
>    
> 
> I am working on a Korg Polysix with the usual tuning problems.  I replaced the
> photo coupler with a VACtrol and resistor mod and still  unable to tune
> keyboard. The high tuning control, VR2, seems  to do nothing. I have tried
> different resistor values with the VACtrol  mod and still have tuning problems
> with the high end of the scale. TIME  CRITICAL repair and going out of my
> mind!(BTW- no battery  corrosion at all!)KLM367 aligned perfectly, KLM 366
> board 
> is  new production. PLEASE HELP!!! Thanks in advance for your  time.
> 
> [Non-text portions of this message have been removed]
> 
>  
>    
> 
> 



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

RE: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem question

2011-03-11 by backshall1 (dsl)

I've definitely seen some Polysix's where VR2 seemed to do nothing and
others where it behaved as expected. I never did figure that one out.
 
You didn't mention VR14. This is the one most responsible for scaling in the
upper octaves. It's the one marked D#4-E4 ADJ.
 
You didn't mention which resistor you replaced or what values, but I assume
it is R93. When replacing the photocoupler with a Silonex or Vactrol part, I
always try putting in a precision trimmer pot here, moving VR1,2,3,14 to
their center positions and adjusting the new trimmer for best scaling before
making adjustments to the other controls.
 
Don B.

  _____
Show quoted textHide quoted text
From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
Andrew Jury
Sent: Friday, March 11, 2011 2:26 AM
To: PolySix@yahoogroups.com
Subject: Re: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem
question


  

Just a thought.... Check the operation of IC31 (s/h in at pin 3, demux at
pin 2).

You won¹t be able to fix the problem in a blind panic. Just stop, think and
take a deep breath.

Good luck,
Andy

On 11/03/2011 03:26, "Bernie GREENBERG" <ptsaudio@sbcglobal.net
<mailto:ptsaudio%40sbcglobal.net> > wrote:

> 
> 
> 
> 
> 
> I am working on a Korg Polysix with the usual tuning problems. I replaced
the
> photo coupler with a VACtrol and resistor mod and still unable to tune
> keyboard. The high tuning control, VR2, seems to do nothing. I have tried
> different resistor values with the VACtrol mod and still have tuning
problems
> with the high end of the scale. TIME CRITICAL repair and going out of my
> mind!(BTW- no battery corrosion at all!)KLM367 aligned perfectly, KLM 366
> board 
> is new production. PLEASE HELP!!! Thanks in advance for your time.
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> 
> 

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






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

Re: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem question

2011-03-11 by Bernie GREENBERG

I have tried VR14 as well as 1,2, and 3. Correct in the resistor being R93, will 
try a trim-pot to see if that helps, but last I had used a reistor sub-box to 
see if it would make any change and it didn't seem sot have much affect. It's 
almost as if the VACTROL isn't doing anythying, in fact it acts much the same as 
when the original photo-isolator was in place.  BTW oscillators seem to align 
very well and I don't suspect any problems outside of the KLM366B, but someone 
had mentioned aligning the DACs on the KLM368a board; didn't touch them as the 
it seems to work OK aside from the tuning issue. Also, looked through my factory 
service manual and didn't see anything about aligning that board. 


The bulk of the problem seems to be in the upper-most registers but not 
exclusively. Ready to shoot this thing! 






________________________________
Show quoted textHide quoted text
From: backshall1 (dsl) <backshall1@bellsouth.net>
To: PolySix@yahoogroups.com
Sent: Fri, March 11, 2011 7:24:40 AM
Subject: RE: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem question

  
I've definitely seen some Polysix's where VR2 seemed to do nothing and
others where it behaved as expected. I never did figure that one out.

You didn't mention VR14. This is the one most responsible for scaling in the
upper octaves. It's the one marked D#4-E4 ADJ.

You didn't mention which resistor you replaced or what values, but I assume
it is R93. When replacing the photocoupler with a Silonex or Vactrol part, I
always try putting in a precision trimmer pot here, moving VR1,2,3,14 to
their center positions and adjusting the new trimmer for best scaling before
making adjustments to the other controls.

Don B.

_____ 

From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
Andrew Jury
Sent: Friday, March 11, 2011 2:26 AM
To: PolySix@yahoogroups.com
Subject: Re: [PolySix] TIME SENSITIVE REPAIR- Polysix tuning problem
question

Just a thought.... Check the operation of IC31 (s/h in at pin 3, demux at
pin 2).

You won¹t be able to fix the problem in a blind panic. Just stop, think and
take a deep breath.

Good luck,
Andy

On 11/03/2011 03:26, "Bernie GREENBERG" <ptsaudio@sbcglobal.net
<mailto:ptsaudio%40sbcglobal.net> > wrote:

> 
> 
> 
> 
> 
> I am working on a Korg Polysix with the usual tuning problems. I replaced
the
> photo coupler with a VACtrol and resistor mod and still unable to tune
> keyboard. The high tuning control, VR2, seems to do nothing. I have tried
> different resistor values with the VACtrol mod and still have tuning
problems
> with the high end of the scale. TIME CRITICAL repair and going out of my
> mind!(BTW- no battery corrosion at all!)KLM367 aligned perfectly, KLM 366
> board 
> is new production. PLEASE HELP!!! Thanks in advance for your time.
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> 
> 

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

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


 

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

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