Discussion about the Korg PolySix synthesizer

I had to set my 367 clone aside for some time and finally had a chance to get back to it. Sadly I can't get past that first step in the calibration. Patch LEDs 1-8 won't light up no matter what I do. I combed the earlier threads in the hopes of pinpointing the problem but so far it hasn't yielded results. One downside to my build here was that I originally set up headers that turned out to be problematic.

I followed the steps in an earlier thread:

- Check the continuity of the test mode switch
- Make sure C28 is correctly positioned
- Check resistive values around IC27
- Carefully examine circuitry around IC33

I checked all resistor values. Some had some dips in resistance now that they were soldered onto the board but it didn't strike me as abnormal. Numerically they checked out so I carried on.

I checked all the caps and diodes against one of my original boards.

I've started to check all the voltages on the ICs. If a scope can show me the logic pulses you refer to on CN10 I should be able to hook something up but I'm pretty new to that. I only have a probe that connects to a sound card and I'm using an app called 'Scope' [go figure :)].

Any help would be greatly appreciated. Thanks!

Hi!

You know I had the very same problem last week with a new board I was
building. I just couldn¹t get the calibration of the d/a converter right.
What had happened was I had selected the wrong resister for R84. It should
be 1K 1%. 1% resistors have a four band colour scheme where the fourth
denotes the number of zeros. I had mistaken it for a three band resistor and
soldered in a 10K 1%. So do be absolutely certain that R56, 57, 73, 74, 75,
83, 84, 85 and VR6/7 are the right values. Also check that you have soldered
the test switch in the right way and that you are in the default mode (see
Fig 1 service manual, section 8) and that the Œmanual¹ mode is selected.

Although I doubt it highly you might also want to substitute IC27 and let us
know which DAC chips you used for the clone board?

Cheers,
Andy


On 13/01/2011 01:01, "ML" <f115@rocketmail.com> wrote:

>  
>  
>  
>    
> 
> I had to set my 367 clone aside for some time and finally had a chance to get
> back to it. Sadly I can't get past that first step in the calibration. Patch
> LEDs 1-8 won't light up no matter what I do. I combed the earlier threads in
> the hopes of pinpointing the problem but so far it hasn't yielded results. One
> downside to my build here was that I originally set up headers that turned out
> to be problematic.
> 
> I followed the steps in an earlier thread:
> 
> - Check the continuity of the test mode switch
> - Make sure C28 is correctly positioned
> - Check resistive values around IC27
> - Carefully examine circuitry around IC33
> 
> I checked all resistor values. Some had some dips in resistance now that they
> were soldered onto the board but it didn't strike me as abnormal. Numerically
> they checked out so I carried on.
> 
> I checked all the caps and diodes against one of my original boards.
> 
> I've started to check all the voltages on the ICs. If a scope can show me the
> logic pulses you refer to on CN10 I should be able to hook something up but
> I'm pretty new to that. I only have a probe that connects to a sound card and
> I'm using an app called 'Scope' [go figure :)].
> 
> Any help would be greatly appreciated. Thanks!
> 
>  



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

Hi Andy et al!

Here's what I have so far:

R56 - 14.95K
R57 - 10.09K
R73 - 0.995K
R74 - 250.4
R75 - 19.93K
R83 - 1.796K (1/4 Watt though)
R84 - 0.995K
R85 - 4.63K

VR6 - W201 
[http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1285]
VR7 - W501
[http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1293]

Test switch is positioned this way:
	- Normal: Open
	- Test Mode: 1 & 2 selected

Synth is set to default mode
Manual mode isn't functioning in either normal or test mode so 

IC33 DAC is DAC08CPZ #1014
[http://canada.newark.com/jsp/search/productdetail.jsp?sku=59K7898]


I can pull R83 from an original board and I could certainly try to de-solder an original DAC too. I've had mixed results de-soldering ICs in the past so I'm apprehensive (but willing).





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

>
> Hi!
> 
> You know I had the very same problem last week with a new board I was
> building. I just couldn¹t get the calibration of the d/a converter right.
> What had happened was I had selected the wrong resister for R84. It should
> be 1K 1%. 1% resistors have a four band colour scheme where the fourth
> denotes the number of zeros. I had mistaken it for a three band resistor and
> soldered in a 10K 1%. So do be absolutely certain that R56, 57, 73, 74, 75,
> 83, 84, 85 and VR6/7 are the right values. Also check that you have soldered
> the test switch in the right way and that you are in the default mode (see
> Fig 1 service manual, section 8) and that the Œmanual¹ mode is selected.
> 
> Although I doubt it highly you might also want to substitute IC27 and let us
> know which DAC chips you used for the clone board?
> 
> Cheers,
> Andy
> 
> 
> On 13/01/2011 01:01, "ML" <f115@...> wrote:
> 
> >  
> >  
> >  
> >    
> > 
> > I had to set my 367 clone aside for some time and finally had a chance to get
> > back to it. Sadly I can't get past that first step in the calibration. Patch
> > LEDs 1-8 won't light up no matter what I do. I combed the earlier threads in
> > the hopes of pinpointing the problem but so far it hasn't yielded results. One
> > downside to my build here was that I originally set up headers that turned out
> > to be problematic.
> > 
> > I followed the steps in an earlier thread:
> > 
> > - Check the continuity of the test mode switch
> > - Make sure C28 is correctly positioned
> > - Check resistive values around IC27
> > - Carefully examine circuitry around IC33
> > 
> > I checked all resistor values. Some had some dips in resistance now that they
> > were soldered onto the board but it didn't strike me as abnormal. Numerically
> > they checked out so I carried on.
> > 
> > I checked all the caps and diodes against one of my original boards.
> > 
> > I've started to check all the voltages on the ICs. If a scope can show me the
> > logic pulses you refer to on CN10 I should be able to hook something up but
> > I'm pretty new to that. I only have a probe that connects to a sound card and
> > I'm using an app called 'Scope' [go figure :)].
> > 
> > Any help would be greatly appreciated. Thanks!
> > 
> >  
> 
> 
> 
> [Non-text portions of this message have been removed]
>

I¹ve just been re-reading your post and you say that none of the LEDs light
at all? Does A1 light when the P6 is first switched on and not in Œtest¹
mode? 

Cheers,
A


On 13/01/2011 17:07, "ML" <f115@rocketmail.com> wrote:
>    
> 
> Hi Andy et al!
> 
> Here's what I have so far:
> 
> R56 - 14.95K
> R57 - 10.09K
> R73 - 0.995K
> R74 - 250.4
> R75 - 19.93K
> R83 - 1.796K (1/4 Watt though)
> R84 - 0.995K
> R85 - 4.63K
> 
> VR6 - W201 
> [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1285]
> VR7 - W501
> [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1293]
> 
> Test switch is positioned this way:
> - Normal: Open
> - Test Mode: 1 & 2 selected
> 
> Synth is set to default mode
> Manual mode isn't functioning in either normal or test mode so
> 
> IC33 DAC is DAC08CPZ #1014
> [http://canada.newark.com/jsp/search/productdetail.jsp?sku=59K7898]
> 
> I can pull R83 from an original board and I could certainly try to de-solder
> an original DAC too. I've had mixed results de-soldering ICs in the past so
> I'm apprehensive (but willing).
> 



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

No, not even then. No 1-8 LEDs at any time.




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

>
> I¹ve just been re-reading your post and you say that none of the LEDs light
> at all? Does A1 light when the P6 is first switched on and not in Œtest¹
> mode? 
> 
> Cheers,
> A
> 
> 
> On 13/01/2011 17:07, "ML" <f115@...> wrote:
> >    
> > 
> > Hi Andy et al!
> > 
> > Here's what I have so far:
> > 
> > R56 - 14.95K
> > R57 - 10.09K
> > R73 - 0.995K
> > R74 - 250.4
> > R75 - 19.93K
> > R83 - 1.796K (1/4 Watt though)
> > R84 - 0.995K
> > R85 - 4.63K
> > 
> > VR6 - W201 
> > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1285]
> > VR7 - W501
> > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1293]
> > 
> > Test switch is positioned this way:
> > - Normal: Open
> > - Test Mode: 1 & 2 selected
> > 
> > Synth is set to default mode
> > Manual mode isn't functioning in either normal or test mode so
> > 
> > IC33 DAC is DAC08CPZ #1014
> > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=59K7898]
> > 
> > I can pull R83 from an original board and I could certainly try to de-solder
> > an original DAC too. I've had mixed results de-soldering ICs in the past so
> > I'm apprehensive (but willing).
> > 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

Right, check the voltages at CN10! If you have a logic problem or scope you
will need to see if you have pulse trains on pins 1 to 14. A very common
problem is that you really do need to solder the connections on the top of
this socket as it is a right angled one and needs to be as strong as
possible. If you are getting logic levels at CN10 but nothing at the other
end on the right-hand top panel board, check where the coloured wires
terminate. They have a habit of snapping off whilst the lid is opened!

Cheers,
Andy


On 13/01/2011 19:33, "ML" <f115@rocketmail.com> wrote:

>  
>  
>  
>    
> 
> No, not even then. No 1-8 LEDs at any time.
> 
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > I¹ve just been re-reading your post and you say that none of the LEDs light
>> > at all? Does A1 light when the P6 is first switched on and not in Œtest¹
>> > mode? 
>> > 
>> > Cheers,
>> > A
>> > 
>> > 
>> > On 13/01/2011 17:07, "ML" <f115@...> wrote:
>>> > >    
>>> > > 
>>> > > Hi Andy et al!
>>> > > 
>>> > > Here's what I have so far:
>>> > > 
>>> > > R56 - 14.95K
>>> > > R57 - 10.09K
>>> > > R73 - 0.995K
>>> > > R74 - 250.4
>>> > > R75 - 19.93K
>>> > > R83 - 1.796K (1/4 Watt though)
>>> > > R84 - 0.995K
>>> > > R85 - 4.63K
>>> > > 
>>> > > VR6 - W201 
>>> > > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1285]
>>> > > VR7 - W501
>>> > > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=62J1293]
>>> > > 
>>> > > Test switch is positioned this way:
>>> > > - Normal: Open
>>> > > - Test Mode: 1 & 2 selected
>>> > > 
>>> > > Synth is set to default mode
>>> > > Manual mode isn't functioning in either normal or test mode so
>>> > > 
>>> > > IC33 DAC is DAC08CPZ #1014
>>> > > [http://canada.newark.com/jsp/search/productdetail.jsp?sku=59K7898]
>>> > > 
>>> > > I can pull R83 from an original board and I could certainly try to
>>> de-solder
>>> > > an original DAC too. I've had mixed results de-soldering ICs in the past
so
>>> > > I'm apprehensive (but willing).
>>> > > 
>> > 
>> > 
>> > 
>> > [Non-text portions of this message have been removed]
>> >
> 
>  
>    
> 
> 



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

Will do. Incidentally mine is now upright. I had to replace those smaller headers I had put in with molexes. I know I had continuity between the 367 and the top panel at hte other end but I'll confirm the voltages and see if I can figure out what I'm looking at on the scope :) Does the the location of ground matter in this case?



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

>
> Right, check the voltages at CN10! If you have a logic problem or scope you
> will need to see if you have pulse trains on pins 1 to 14. A very common
> problem is that you really do need to solder the connections on the top of
> this socket as it is a right angled one and needs to be as strong as
> possible. If you are getting logic levels at CN10 but nothing at the other
> end on the right-hand top panel board, check where the coloured wires
> terminate. They have a habit of snapping off whilst the lid is opened!

OK. Pin 16 on CN10 is ground but just about anywhere earthy will do. What
you are looking for a nice set of rectangular pulses on pins 1-14. If you
see nothing measure the voltages on these pins. If they are all lower then
2v then I think we can assume the CPU has stalled or something just as
tragic! If you reused the black ceramic resonator from the old board make
sure the legs haven¹t dropped off. They do come adrift at will. Come to
think of it also see if there is a pulse at pin 1 of the CPU, that should
tell us a lot.

Cheers,
Andy


On 13/01/2011 19:54, "ML" <f115@rocketmail.com> wrote:

>  
>  
>  
>    
> 
> Will do. Incidentally mine is now upright. I had to replace those smaller
> headers I had put in with molexes. I know I had continuity between the 367 and
> the top panel at hte other end but I'll confirm the voltages and see if I can
> figure out what I'm looking at on the scope :) Does the the location of ground
> matter in this case?
> 
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > Right, check the voltages at CN10! If you have a logic problem or scope you
>> > will need to see if you have pulse trains on pins 1 to 14. A very common
>> > problem is that you really do need to solder the connections on the top of
>> > this socket as it is a right angled one and needs to be as strong as
>> > possible. If you are getting logic levels at CN10 but nothing at the other
>> > end on the right-hand top panel board, check where the coloured wires
>> > terminate. They have a habit of snapping off whilst the lid is opened!
> 
>  
>    
> 
> 



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

Thanks so much. I'm on it.

A faulty crystal! My goodness. Relieved. At least I'm at step 1! :)

Nice job everybody!

On Thu, Jan 13, 2011 at 1:14 PM, ML <f115@rocketmail.com> wrote:

>
>
> A faulty crystal! My goodness. Relieved. At least I'm at step 1! :)
>
>  
>


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

Looks like the key assign switches also light up and in my case Chord Memory remains on the whole time, whether in test mode or not. I also can't seem seem to fire up Manual in order to begin the DA calibration, but maybe I'm getting ahead of myself...

Well ~ getting there slowly! :)