Fornicus - bias issue

[joeyd]

I'm trying to track down what's going on in my fornicus. The threshold pot and the weight and sag switches aren't doing anything perceivable (I feel like a 10uf cap should be very obvious). I know signal is passing (I audio-probed everything to check), I've verified the components are correct, and I reflowed all the joints. The other half of the circuit seems to be functioning correctly.

There are two things that look suspect to me. The orange LED is always on (it looks like it's connected to the vref so maybe that's right?). I probably installed a closed spst switch because the red LED seems to always be on in the circuit vs. when the "boom" switch is engaged. At any rate, the red LED doesn't seem to be effecting the audio.


The trimmer is fully clockwise.

Any help is appreciated!

 

[Fama]

I hope someone can clarify things, but according to https://forum.pedalpcb.com/threads/fornicus-leds.20394/#post-274391 and from what I remember of my own troubleshooting, you want a decent difference in VREF between D1 and D2 - the part I'm not sure about is which way you want it. I think you want D1 to be higher than D2, so that when you play lightly, D2 conducts, but if you play hard, D1 conducts and it then sags?

That's the part I'm not sure about and my brain is still groggy so I can't figure it out right now. But either way, I suspect that might be the issue you're having, especially if it seems to work otherwise.

I assume you've tested with the trimmer the other way around too?