Aion Electronics "Rat" Helios Distortion - drive knob killing volume

[Fiereblade]

Hello hello,

I've successfully completely 13 Aion projects, but got a bit stuck on this one... hoping that someone might be able to point me in the right direction.

The documentation can be found here: https://aionelectronics.com/project/helios-proco-rat-distortion-pcb/

My issue is:
When the pedal is engaged and the drive knob turned completely off, I get a clean guitar sound and the other knobs work as expected. However when I turn the drive up just slightly, there's a fine point where I get a crunchy/distorted sound but after that the effect cuts out entirely.

In my debugging, I've replaced the drive pot, and tried tried a number of ICs (OP07, CA3130EZ and LM301AN) but I still have the same problem.

Here are the voltages of the IC with the LM301AN installed:
With the drive pot down/off (effect "works" lol):
1- 1.59
2- 5.11
3- 4.66
4- 0
5- 1.52
6- 5.2
7- 10.4
8- 4.8

With the drive pot at 50% (effect does not work)
1- .03
2- .35
3- 4.43
4- 0
5- 1.5
6- 10.13
7- 11
8- 10.16

With the drive pot at 100% (effect does not work)
1- .03
2- .06
3- 4.9
4- 0
5- 1.49
6- 10.21
7- 11
8- 10.21

Thanks!
- Joel

Here are some photos:

[PRR]

> With the drive pot

"Distortion" pot?

> 2- .35
> 6- 10.13

C5 C6 or something near there is shorted to ground.

[Fiereblade]

Oops, yes Distortion pot.

Thanks for the ideas! I'll dig in there tomorrow and see what I can find!

[Fiereblade]

I didn't notice anything obvious with C5 or C6 so I replaced both of them with new capacitors and tested after each. Looks like there was a problem with C6 as it worked as soon as I replaced it. Thanks so much for the assistance!