Category Archives: mccoy

Turning a jimmy dunplop High Gain pedal into a vintage specced wah wah

Oh well.. i got this volume pedal for cheap. I also rescued some BC173B and 4x early 70es italian inductors (red, white) from a Farfisa organ i recently dissected.
I bought a vox v847 pcb from a reputable greek seller on ebay.
After cross checking caps and resistors differences, i took the plunge to make a mccoy of sorts.



The mccoy calls for a bipolarised 4uF cap. Somewhere i read the original also used a 3.9uF so a tropical fish of this value was chosen.
I also tried to change the resistance value of the pot from 250k down to 100k as called for by putting a 166 resistor between the lugs 1 and 3 of the stock hotpotz.
Transistors measured hfe: 395 and 320. I used the gainier one for q1.
Upon firing it, the wah was almost non existent.
Measuring the inductor, it appeared to be the same Henrys value as the black 80es inductor of my dunlop crybaby so possibly it’s not the inductor’s fault.
I changed the 3.9uF tropical fish for a 4.7uF blue polarised Philips.
Much better..
I also changed the pot’s range of sweep, using the “pinion mod”, adding more bass to the curve.

To be contd

yours truly