[sdiy] What is a korg 2069AD?

[TooManySynths]

> As I recall, the filter chip in the DW-8K is the
> same as the filter chip in 
> the Poly 800 (could be wrong).  If it is, it's a
> very nice little thing, 
> capable of self-oscillating and so on.

That is correct. I discovered the poly800 schemos on
the web and thought to check to see if it uses the
same chip. I presume at most the poly800, dw6000 and
dw8000 would use this chip. I can't imagine anything
else korg was doing at the time that would use that
particular chip.  In fact, I believe the next major
korg synth post dw8000 was the M1.  


So, a little reverse engineering of the DW circuit
board combined with the POLY800 schematics has given
me some information.  Do any of you know any more than
about this chip. Any question marks you could help me
eliminate would be appreciated.

Pin    function
1      Ground ?
       Schematic says that it is a specific ground
       but I can't read what it says.

2      Level 1 (cv input ?)
       This pin goes to a common bus on the DW
       so it is a control input that would affect
       all voices in a polysynth

3      Level 2 (cv input ?)
       This goes to a pot and to a voice specific
       control point on the DW.

4      Resonance control input
5      Not connected on either synth
6      24db VCF output
       connects to pin seven on the DW, but organized
       differently on the poly800

7      VCA in
       I'm pretty sure this is the signal input
       for the VCA, but then, what is 
       sig1 and sig 2 (see below)

8      VCA log control input
       goes to ground on the DW, but the poly800 
       appears to label this the VCA log input.
       Although I know better, it follows as it is 
       next to the VCA lin input, and the VCF control
       inputs are aligned the same way.

9      VCA lin control input
10     VCA out
       I think this is the VCA output, that's what 
       it's labeled. On the DW it goes into an opamp
       buffer and then out to a voice specific point.
       On the Poly800 it goes to pin 19 which is VCF
       input something or other, but on the DW, pin 
       10 connects through a resistor to a point 
       common to all voices.  So pin 19 is NOT the VCF
       input. (see pin 19 below)

11     VEE,GND (this, I believe is the power ground)
12     VSS, - supply voltage, probably -12 to -15
13     VCF lin control input
14     VCF log control input
15     VCF caps connect these pins to ground
16     |
17     |
18     |
       I have no details on the specifics. In both
       synths these pins go to ground through a
       .001 mf poly cap.

19     Ahh, the mystery pin. On the DW it connects
       through a resistor to a common control point.
       On the p800 I think it connects to pin 10,
       however, the p800 schematic is quite hard to
       read so this may not be right.

20     Sig2 input
21     Sig1 input
22     VCC, + supply voltage, +12 to +15


Ok,Here's what I think, if you know better, please 
correct me.

The audio inputs to the filter should be supplied to
pins 21 and 20. The gain of each input is controlled
by a cv input on pins 2 and 3 respectivily. Resonance
CV input should be supplied to pin 4, cuttoff CV
should be applied to pins 13 and 14 for lin and log
control respectively.  The output of the VCF is taken
from pin 6 and, like on the DW, can be fed right into
pin 7, the VCA input. Note, on the DW it goes through
a np electolytic cap of 10mfd.  The VCA is controlled
via pins 9 and 8 for lin and log control respectively.
The output of the VCA is taken from pin 10 and fed
into whatever opamp buffer you wish.  

Pins 1 and 11 go to ground, pins 12 and 22 go to
negative and positive power respectively.  Pins 15
through 18 connect to ground through .001 mfd poly
caps. I presume the values can be varied.

Pin 1 is a minor mystery, what does it ground?

The major mystery are pins 5 and 19.  I think both
relate to the VCF, pin 19 should control something,
what I don't know.  Perhaps pin 5 is a 12db output? I
have no idea, I'm just guessing.

Any help would be apprecieated.  At least if there
isn't any more info, this much will be in the
archives.

Thanks
Daryl
 

PS: I almost forgot about the firmware request:

> I don't offhand know what version of the firmware
> you have, but if its the 
> fixed version (where they got rid of at least a
> little bit of the 
> key-bounce phenom) I wouldn't mind having it....  :)

The bad news is, I have no idea.  Further, since I was
in need of a 27C512 to upgrade the os in my regelwerk,
I scraped half of the label off checking only to find
out it was not a 27c512.  

Tell me how I'd know which rev it is?

Thanks
Daryl



__________________________________________________
Do You Yahoo!?
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger
http://im.yahoo.com