Korg Poly800/EX800 Users

On Wed, 2009-02-18 at 05:40 -0800, Michael Hawkins wrote:
> Tim,
> 
> I recommend you wait until we have a bit more discussion about the
> operation of the joystick board.
> 
> I wouldn't want to see you blow your Poly up.
> 
> I am quite busy today, but will attempt to provide some additional
> instructions tomorrow.
> 
> Zoinky is right that we need to use linear pots. What are all of the
> markings on your pot's? When you move the pots through their full
> rotation, does the voltage move smoothly or does it move slowly and
> then at each end, suddenly jump up or down?

The pots are a bit funny, with a kind of centre-tap on them.

As far as the output from the joystick board goes, there are two
connectors - CN1B and CN8B.  CN8B goes to the bend range slider, CN1B
goes to CN1A on the main board.  CN1A is as follows:
1 - +5v
2 - 0v
3 - -5v
4 - X output
5 - Y output

The X and Y outputs are centred around 2v, and go from 0v fully right or
up to 4v fully left or down.

I haven't drawn out the circuit on the joystick PCB yet, but I suspect
it's some sort of voltage regulator and biasing thing.

Have a look at the circuit below for an idea of what might work.

http://www.gjcp.net/synth/joystick.jpg

Gordon