How to Troubleshoot Pedal Pi

I'm convinced I'm nearly there and the problem is with the output stage. Anything else I can do?

The output stage is pretty simple, if ou have a look at the schematic:
www.electrosmash.com/media/kunena/attach...dal-pi-schematic.png

You can see that there are simply 2 resistors (R6 and R7) going to a cap (C6) and then an op-amp filter.
What kind of equipment do you have?: multimeter? oscilloscope?...

We have a fella having very similar problems and in his case it was just dry-joints / false connections, check reply #998 in this topic.

Can I try following the voltage round the components for the output stage? If so what voltages should I be looking for? I imagine the voltage is supposed to change when it passes a resistor.

If you dont have an oscilloscope (like most of the people) is not easy to follow the signal.
In my opinion the output stage is pretty simple:
- If you could measure with the multimeter continuity function (the one that beeps when 2 points are connected) that all the parts are connected (i.e check that R6 is connected to the pi Zero PWM0 pin, that R7 is connected to PW1, that R6 and R7 other end are connected to C6, that C6 other end is connected to GND, etc...)
- Also double check that you have 5V, 1V6 and 3V3 at the test points.

I just noticed R7 is measuring 75Kohms on the multimeter when it's listed as 300K in the BOM. I checked the hi picture and the colored rings on the resistor are the same. I'm not sure what that means.

Its weird because I dont use any 75K resistor in this design, its probably because when they are soldered other resistors add their parallel resistance to the one you are measuring, could you maybe post a picture or send it to info at electrosmash.com?

The components look to be placed properly, the only thing that can be causing problem is the solderless header.
Load the OS we have (uploaded in Mega) in the " How to Start Programming Pedal-Pi " just to make sure that you dont have any software issue.

With that header I would load the sinewave generator and slightly touch/move/press down the header to make sure that there are no false connections.

OMG It works!

That's fantastic news!!! Well done I know that sometimes can be a bit frustrating... I hope you have at least improved your troubleshooting skills.