TRACED...Zvex Fuzzolo. But I need help with verification.

Posted by Ciaran Haslett on May 22, 2015; 6:22pm
URL: http://guitar-fx-layouts.238.s1.nabble.com/TRACED-Zvex-Fuzzolo-But-I-need-help-with-verification-tp20721.html

First time attempting anything like this so be gentle

I couldn't find a schematic for this in all the usual places so I got a lend of a friends and thought I'd try my hand at reverse engineering it

I worked through it and all went well until I got to the MOSFET.  The pots were on a second level PCB sitting over this section and I didn't have the stomach to unsolder 14 header pins on a pedal that wasn't mine.  The boards are dual layered with quite a few vias making for some head scratching moments but I soldiered through.

Anyway....

As you can see...the first 3/4s of it are basically a Mastotron with some pots replaced with fixed resistors or removed altogether.  So far so good.

Now the trouble begins.  There's a BS170 with a zener diode (couldn't identify the model..I could only make out "39B" printed on one side) that seems to be tied to the gate and source.  I did a bit of research and it seems common to tie the drain and source together rather than the gate and source for clipping...if that's what it's even doing here!

I'm 90% sure the rest is fine but again this is my first trace....hell its the first time I even opened Eagle to draw the schematic!  Which is why the pots are trimmer symbols!

So I'm calling all breadboard warriors!  Anyone have an hour to spare and verify/correct this?

I'm away for a long weekend tomorrow so I won't get a chance to have a go or answer many questions you may have.  I figured if I just put this here, you lot can do the dirty work

Oh and for the purists...

the 750r on the input was a 5% carbon film resistor while the rest were metal film 1%
The 10uf electro was 20% while the rest were 10%

Cheers folks

EDIT:  Schematic updated to correct values and VERIFIED