| br>Built this the other night, fun module for sure but I have a couple probs with my build I'm hoping someone can help out with.
It works but the bias on the 1st channel vca sends out squares or straight DC (spikes in time with envelope rate) when it's biased into negative. And the pot doesn't zero out the vca, there's always bleed. The trimmer pots for *both* vca's don't appear to do anything when I look at the scope (I've followed calibration procedure listed in user guide). Anyone want to give me a clue?
Also, which resistors are the ones for the LED's? I changed the bright whites out for reds but it's a little too dim now.
Is there a schematic around? I didn't see one on the hex site.
I have checked for solder bridges and swapped out the chips that there were doubles of to see if the problem moved, it didn't.
I'm wondering if I cooked one of the transistors when I installed it but the question is which one would I look at?
Here's the positive bias on the vca (test signal 1khz sine from function generator at about +/-5v), looks ok but I do notice the negative part of the signal saturates before the positive side and the vca trimmers on the back don't seem to do anything...
Here's what happens on the negative side of the bias pot for channel 1, the pulse shown starts out a lot wider but after about a second or 2 it's all just DC voltage at the high level, no pulse at all, the pic is shown in between those two states...
Here's some audio I did with it where you can hear one side of the vca never closes, it's the Jupiter Storm noise in the right channel...
[soundcloud url="https://api.soundcloud.com/tracks/167631381" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /] br> br>