this modifies the sample and hold section to allow different waveforms to be inserted instead of noise, which is hardwired.
break the noise hardwire by redirecting the middle wire of the switch S1 directly to R18 100 Ohms (the side opposite J4). another wire from this point on R18 can be added to send the noise to the "switch" lug on the jack, to default noise when nothing is plugged in.
add a 100 Ohm resistor at pin 11 of U7 MAX365, there is a a solder hole conveniently built in here, and wire it to the "tip" lug on the jack.
the "ground" lug on the jack goes to ground.
to avoid drilling another hole in the faceplate, i unwired and used the preexisting QUANTIZED jack because i never use that feature. a little black tape on the silkscreened word "QUANTIZED", and you're done! now instead of random voltages, you can insert triangle waves for stair-stepping, noise from another source, whatever.
not responsible for any damage or injury.