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Sorry, nothing else is jumping out at me.
Stabs in the dark:
- I can't read the values of your caps or some of the resistors. Did you check them with a DMM before you populated the board? You're electrolytics all look very similar. One of them should be a different value from the rest.
- Have you tried swapping the IC again? Maybe it got cooked.
- It's hard to tell from the picture, but are both of your ground rails on the breadboard connected? It looks like the rightmost jumper connects them, but I can't see it clearly enough. Have you used this breadboard successfully in the recent past?
- Finally, have you tried running a small blade between the vero strips to cut any invisible solder bridges?
If I get a chance (this is a pretty big 'if' since I have a two-month-old baby), I'll check the voltages on mine. I've modified the hell out of it, so they might not be exact, but it might help.
When you finally do get it working (I have faith), you'll want to run it off of a battery or a very well regulated adapter or the hum might be unmanageable. This circuit expects a battery, so the voltage divider feeding the non-inverting input of the op-amp isn't properly filtered. This can be fixed but you'd need to redesign the layout.
Setting the bias on this thing can be tricky. You can't bias by voltage because jfets have a notoriously wide spread in Vgsoff. That's why you need a trimmer. There's a very small sweet spot on the trimpot that just barely turns the jfets on. On one side it acts like a clean(ish) booster with no compression (jfets all the way off). On the other side it compresses everything equally and it just becomes an attenuator (it gets very quiet, even silent because the jfets are wide open and the input signal is all getting shunted to ground). Set the trimmer to clean boost territory and then inch toward the quiet side until the volume just starts to drop, then leave it there. That's the spot where the jfets just open up for loud signals but not for quieter ones, and it's just compresses the peaks. You can go a tiny bit further if you want to reduce the clickiness, but not much more. It's good that you swapped out the external control for the trimmer. It's definitely a set-and-forget trimmer, just for setting the bias. It's not a compression control and it doesn't really give a range of different sounds. Its only function is to compensate for the variation in jfets.
I added an actual compression control to mine. I swapped the 10k resistor that sets the op amp gain for a 5k resistor in line with a 10k pot. That gives me a range of gain on the op amp. More gain equals more compression. So I have the option of both increasing and decreasing the compression. I always end up leaving it in the stock position. That's where it sounds best to me.
It's a great little pedal. I think you'll like it a lot, so keep at it until you figure out what's wrong. It's worth it.
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