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OK, the voltages for the dual op amps are wrong, but they are probably correct if you are numbering the pins incorrectly. This is the correct numbering scheme

It sounds as if almost everything is working as it should. Sounds like you won't need to replace U3 fingers crossed. I am a little hazey on exactly how this bypass works, but from my understanding I would be suspicious of the capacitor that is labelled C16 in the above schematic. I think it's...

Yes. Q4 is for bypass, and Q10 carries the effect signal. It is the network around U3 that is doing the switching. Does the LED turn on when the effect is working and off when the effect is bypassed?

OK, it looks like it is a FET switching setup, but the switching bit is mostly missing from the schematic. If you see the lower schematic of the 2, there are 2 FETs at the bottom near the output (unfortunately they are not marked with component numbers so I can't point out better than that...

I don't know if that is the maximum gain you are supposed to get. I don't have one. I do know that I like the sound though. Will definitely consider for my next order. Can you end up with too many drive pedals?

Before I went about removing a dual gang pot I would be measuring it. Power off. Multimeter on ohms setting connected to the wiper and and end (the end in use). Turn the dial and measure each gang. You should get a sweep through the range from 0 to 250k (if using a 500k pot remember there...

Where does the design come from? A drop of 3.77V across that resistor would indicate that the circuit is drawing just under 40mA. It is only a guess but I would have thought that was not a massive current draw for a pedal. It is odd that you measure open circuit across the voltage divider...

What are you using for a power supply? Try a battery clip soldered to a power jack and see if you still get squealing. Some power supplies have enough noise in the power to do this - especially with high gain pedals. A battery will be pure DC though.

The wiring in the documentation is correct. You shouldn't be using a TRS cable, you need a regular mono guitar cable. Tip goes to the input of the board, ring goes to the black wire of the battery snap, and the shield connection goes to the board ground pad. That way inserting a cable into...

If you are looking at parts of the circuit that are unique to -1, then on the schematic you are basically looking at R11 through Q2, IC 1.2 and through to IC2.2 I think. I am a bit hazy on it, but I think the purpose of that network is basically to buffer and filter what starts out as a square...

So, with level and drive all the way down you still get the tone? What happens with level down, drive down and then shift the mix from side to side?

Also, where did you get your J201s? They are notorious for being faked in TO92 packaging

Don't go swapping out parts until there is some idea what the problem is. Does the oscillation occur at all settings of all controls or is it selective?

It sounds like a capacitor is charging up and when it gets to full charge it is stopping the power supply. I would be checking the power supply caps - for orientation, for the correct value and also to make sure they aren't shorted to somewhere they shouldn't be. Also it might be useful to...

I could be a bit wrong about my understanding, but my understanding of an op amp is that it works by sending a signal out the output that will make both the inputs the same. That is why you need a feedback loop back to the input. In this case one of the inputs is grounded, so the output will...

I plug an old MP3 player into the input jack using a 3.5mm to 3.5mm cable (standard MP3 player or phone audio cable) and a 3.5mm to 6.35mm converter. Just play a few of your favourite songs. You are really mostly listening to see if you have signal at first, rather than what the pedal is doing...

If you measure that the correct lugs are connected in each position, and that there are no lugs connected that shouldn't be, then your switch is OK. What you said about connections in post 3 is not correct though. This is what to look for The switch board may also connect some of the lugs...

Measure voltages to the op amp, FV1 and EEPROM

2n7000s and a single 1n34a is exactly what I used for clipping in my ADHD pedal. The arrangement is a bit different (clipping to ground rather than op amp feedback loop) but it sjhould still work.

Q4. The emitter voltage you measured is higher than the base voltage. If that is correct then I think that will turn off that transistor. I would be looking at the component values around those legs to see if you may have the wrong value there somewhere