Debugging a built pedal (one knob fuzz)

[oscillateur]

Hi,

I recently received as part of a super cool secret santa package a modified (oscillating) coloursound one knob fuzz.
The issue is that it worked when it left the Czech Republic but during its transit to Tokyo (maybe because of overzealous custom agents ?) something happened and now the pedal only oscillates. When something is plugged in, it's not passed through the pedal anymore.

I thought it would be something obvious like a bad connection between the input jack and the rest of the pedal but I just checked every wire I could find with a multimeter and they all seem ok... What else could I check ?

The power seems ok, the LED lights up and the pedal does produce sound, it's just that the incoming signal seems to get lost somehow.
I'm sort of at a loss here, I'm not really an electronics person

[Scruffie]

You needs an audio probe http://www.diystompboxes.com/wiki/index ... =Debugging

You can also post voltages for the 2 transistors.

[oscillateur]

Thanks for the answer, I'll have a look at that .
The circuit is not super accessible now (sort of glued in a corner) but I think I can safely remove it to do more tests...

[KaosCill8r]

Check the grounds. Sometimes oscillating happens when you remove the ground from the circuit.
I build some oscillating fuzz pedals by connecting the ground to a pot and get some crazy sounds happening.

[eatyourguitar]

oscillation can happen if the gain is too high and the guitar is not shielded. fuzz adds a lot of distortion that makes it hard to know what the input sounds like. you might have a working pedal. or maybe not.

[oscillateur]

The oscillation is intentional on this one, but it should be in addition to the processed input sound, which I don't get. I haven't had time to try the audio probe method mentioned above, maybe during holidays...