Hi, I have built 2 plexi plus circuits with the tone tweaker board. The second one has a drastically lower output than the first, and when I bias Q1,3&5 to 5v I get almost no volume. In the build document the q1 voltages are all 0. When i bias Q1-D to 0, Q2,3&5 all fall in the correct voltages but Q4 is very low (.4ish). I am wondering if my Q4 could be bad, as I know J201s can be iffy these days. Any ideas?
Can add pictures if needed, but the voltages currently are: Q1:0v, Q2:5v, Q3:9.23v, Q4:.43v Q5:4.73v
When I set q1 to 5v, I had NO volume until I was “turned to 11”.
I think the problem is in the Norm channel, as isolated it doesn’t seem correct. Q4 is outside the expected values though so I’m still suspicious of that.
here are some pictures…it’s in a “pedalboard build”.
Thanks everyone! I was able to reset the biases and get the pedal working, albeit not at the 5v. I think the J201 transistors i got were a little out of spec so I had to bias them a bit cold for the desired tone. @wilkie1 & @billy – thanks for the explanation on the Q3-4 source-drain relationship!
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