Intermittent operation?

[suryabeep]

Hi everyone,
I built this on a pcb. Before you start yelling at me about poor design, let me just say that I breadboarded it and it worked perfectly and sounded great. Now that I put this on a pcb however, something's wrong. It works for around 5-10 minutes, and then starts sputtering when I play through it. If I take the power plug out and then put it back in, the pedal works fine again for about 5-10 minutes, and so on.
Voltages on the first tl072 look good, voltages on the second one however are all around 1.4 volts when the sputtering happens.
About the PCB: I designed it so that I could just bypass the charge pump and have 9V operation in case the charge pump acted up and ofc the charge pump emits a high pitched hum so I bypassed the pump in my build
What could be going on? It worked perfectly on breaboard [emoji53]

[Rob Strand]

I built this on a pcb. Before you start yelling at me about poor design, let me just say that I breadboarded it and it worked perfectly and sounded great. Now that I put this on a pcb however, something's wrong. It works for around 5-10 minutes, and then starts sputtering when I play through it. If I take the power plug out and then put it back in, the pedal works fine again for about 5-10 minutes, and so on.

It's because there is no resistor from ybias to pin 3 of IC3A.
When you power-up the cap is discharged and the voltage on pin 3 is "correct".
As time passes the bias current (and leakage) into pin 3 charges the cap.  Eventually IC3A becomes misbiased and the output can only swing in one direction (and hence becomes sputtery).

You should also add a cap between pin 1 + pin2 of IC3A and the volume pot.  As it is you are outputting upto 4.5VDC, not good for a tube amp if one follows.

[suryabeep]

Thank you Rob, you're a legend! Thank you for the explanation, it really helps
on a separate note, why could the 7660 be humming like that? I lifted the schematic directly from numerous examples online. Anyway, if it's a long fix I'll just get rid of it and run on 9V
edit: could I replace it with a TC1044 and get rid of the hum?

[thermionix]

Maybe just more filtering after the 7660?

[Rob Strand]

7660 be humming like that?

It could be layout.  :   make sure there not connections to the traces between the 7660 and the three caps C8, C10, "CD"

It could be because the 10uF (looks like "CD") isn't big enough. 
Try making the 10uF bigger like 47uF

Could be because the ESR of the caps are too high.   Try Tantalums or low ESR caps.  Making the 10uF larger will drop the ESR as well.