I checked the Yoy Yoy Wha Wha I had lying around, and it is true, the schematic hosted floating around does contain some errors with regard to the unit I have here. After completing the check, I find it matches this schematic by diyguitarist:analogguru on August 27 2007 wrote:There exists a schematic from a later version (the wha-wha-yoy-yoy) with plastic transistors. I am not sure if this schema doesn´t contain some errors.
I have some guts from the unit shown, but not from the solder side.
So if your friend could take a photo of the solder-side the schematic could be verified and maybe adapted to the unit of your friend....
http://www.diyguitarist.com/Schematics/BowWowYoyYoy.gif
Except for the transistors which are BC237
the 22nF are 27nF
the 250nF is 220nF
resistor on first transistor's collector is 15k instead of 10k
100 ohm on the 9V
100uF to ground
Was is not often noted, is that there is no bypass. Rather, the pedal switches between Yoy/Wha mode and Volume pedal mode. But some incredible tone sucking going on. I replaced all electolytes in this pedal, might pass to changing to better capacitors. With such a crappy plastic case, you ask yourself why bother.
Tightening the wah pot and setting it up right already made it a decent wah. Don't know about the the Yoy though and a some of bass distortion in the heel position.