Discussion about the Korg PolySix synthesizer

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]
>