Bellum Fuzz Mk1

fractal33

Active member
So I'm putting this together for a friend and this is actually my second attempt because I got so frustrated with the first that after all the socketing and desoldering the PCB was pretty mangled. Anyway, the issue I'm having is an insane amount of hiss/noise. It isn't a hum like 50/60 cycle, but hiss that sounds like white noise and it is there even when the volume of the guitar is all the way down or even with the input unplugged. The noise goes down when I turn the volume of the pedal down as well.

The only change I made from the build docs was I used 100n caps for all the 680n and the one 680p cap. This was suggested by another member here and I tested this out on my previous build which I socketed all caps. I chose not to include D3, D4, and R24 for the sake of troubleshooting, but the problem was still there in the previous build when I had these components installed.

I went through everything on my last attempt of this build with a probe and found the noise dramatically increased at the node of R20, C12, and pin 1 of Q6. When I probed pin 2 of Q6 there was some noise but nothing unexpected from a fuzz pedal. When I probed pin 1 of Q6 however it sounded like someone turned an old TV on max volume and had it on the wrong channel.

I'm really at a loss here, I've spent more time than I'd like to admit trying to figure it out on my own. Would love some input. Thanks!
 

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