Coron distortion III

[Emil]

Hi!

I got this old 80's Japanese Coron distortion III lying around and thought I would do a trace of it in order to learn some more about effects pedals, electronics and schematics. I haven't done anything like it before, and I don't know all the conventions for writing schematics but I gave it a try!

The sound of this thing is not great . It's sounds a little fizzy and lacks sustain. But I think a large part of it is because of the bypass, which is terrible. I can hear the pedal distort in the background when it's off . Otherwise it's a 4558 -  clipping diodes to ground - type distortion that I think could have some potential. Those clipping diodes btw are 5,6v Zeners wired like regular diodes, which surprised me!

Some notes/questions

I have labelled everything according to the pcb as far as possible. But the board labelling does not quite match the parts on it either so I have added some of my own labels where they where inaccurate or missing.

Q5 is just a guess in the schematic. It's marked 304 F1L and comes in a TO-92 case. Don't know what it might be? I thought it could be a J-fet J304 first. But since the middle pin goes to ground (measures 0v) and the others measures around 4,5v, I thought that maybe it would be weird to have the source go to ground like that?

Another guess on my part is that pin 1 from the opamp goes to pin 5. I'm not sure how to tell?

Diodes 1, 4, 5  looks to be the same type, but haven't got any markings on them from what I can see. I'm guessing maybe 1n400X type or similar?

CX2 sits under the board and is impossible to read the value of. It is certainly a small value ceramic cap though. The first number is possibly a 6 so maybe 60pf?

What is that 14007 IC doing? . Is it part of the switching system or something else?

Coron_Distortion_III.pdf