Comprehensive Drive stopped working, super buzzy/fuzzy.

[alsiv23]

Hi, my Comprehensive Drive build worked well at first, but after a couple days it became a little buzzy/cheap sounding at even low drive and now is a complete fuzz-fest even when drive is at its lowest setting. The signal is clean entering the IC, and coming out super distorted. All components between IC input and IC output are outputting fuzz signal, including potentiometer in and out, as tested with an audio probe. I have attached photos, showing the pedal with an audio probe temporarily installed. Does anyone have any suggestions, advice or insight? This is my third pedal build, after building two Propolis Fuzz. I'm curious why it would start fine and then become messed up. Maybe there was a short that ruined the chip itself? I have a multimeter but I wouldn't know what exactly to test to see if this is the case. Thanks ahead of time!

 

[alsiv23]

In lifting one end of those resistors and breaking the connection(s) to VREF_A, you never measured any voltage that exceeded 4.5V (1/2 VCC) at the junction circled in red or at IC1's pins 1-3?


As it should.

I replied about the voltages, however after checking C12 again and desoldering I notice that the annular ring on the underside of PCB for the negative connection is missing. Could this be causing the issue, and is there a way to see if this is the case?

Update: after making a manual connection to ground at this point with a wire, nothing changed.

 

[alsiv23]

A few things came to mind from your description:
1.) C9 isn't properly connected to ground via R11 (10K) and is storing up too much DC voltage by, instead of keeping Vref A steady. Ensure those solder joints and values (note that the cap orientation looks good).

2.) Vref A circuit (you already checked). If one of the component values is wrong or the connections are not solid, it can throw off the voltage being divided.

3.) RC4558 is shorted or internally compromised between pin #3 and #8. I ALWAYS socket my ICs, FETs, transistors, etc. because they are a PIA to unsolder if one fail

Thanks for your input, will I be able to test the chip after removing it to check for shorts and other compromises or will I just need to order a new chip and try that out? Heard that re socketing, I'm going to start doing that as well.