Testing the Voltage Controlled Amplifier

  1. Connect power from the IO board and provide 2.0VDC to R90, as before.
  2. In a quiet room, connect up a pair of low-fi (32ohm or greater impedance) headphones as before: ground the sleeve (the mid pin of j4 is a good ground), and use the tip for probing. Touch the tip to rightmost pin (the one that is not connected to the ground plane) of where the volume potetiometer VR8 will go.
  3. Connect up an alligator clip as it was for testing the gate (clipped to R146) and touch the other end to R3 to generate a gate pulse. You should hear a struck note! Hooray, you're basically done with the analog section of the synthesizer!

Testing the BA6110


These are the voltages that you should see from your BA6110

Pin DC Bias AC signal
1 5.3v 10mv
2 5.3v 0mv
3 0.0v 0mv
4 0.0v 1.2v
5 0.0v 0v
6 5.3v 750mv
7 5.3v 750mv
8 5.3v 750mv
9 12v 0v

Pin4 is the signal from the gate so it should go to 1.2v when the gate is high and 0v when the gate is low

The signal at pin1 is very hard to see except on a clean scope.