TonePad Rat debugging help

[neil411]

Hi,

I need some help with my TonePad Rat (La Rata) build.

I get no sound other than a raspy noise when the strum really hard. Bypass works fine.

I used a audio test probe to trace the audio, I get audio into the IC, but nothing comes out the other side. I have swapped the chip with a new one - no change.

The only parts substitution I made was to use a 2N5457 in place of the 2N5458. I swapped that out for a J201. No change.

I have 9.45 volts going in to the circuit.

My voltages at the IC (an LM308N) are way off:

P1 - 8.89 v
P2 - 0.506 v
P3 - 47.4 mv
P4 - 0 v
P5 - 21 mv
P6 - 0.511 v
P7 - 9.43 v
P8 - 17.6 mv

Help!

[petemoore]

  Test for ~1/2 volts of supply [about 4.5v] at the junction of the voltage divider resistors, they should be the same R value.

[neil411]

Do you mean the two 100k resistors?

http://www.tonepad.com/getFile.asp?id=89

[neil411]

Thanks, I figured it out, I had the wrong value cap in the compensation cap for the IC.