Vox McCoy Clone debug

[spaceace76]

hey everyone, found an old project that needed some TLC, but can't figure out what's wrong with it. I built a "mojo-spec" mccoy wah with the fuzzcentral layout. currently the wah passes signal but doesn't change the frequency. It just sounds a bit loaded down when engaged, slightly less treble.

I have made sure the board is getting voltage (I can post voltages if necessary) and double checked the transistors and their pinouts. Using a tested, fresh battery too. when using a signal probe I can hear the transistors amplify, but after the 470k resistor off Q1, there's no signal. Signal continues all the way to Q2 and to the output but no change when using the pot.  So I would assume that the 470k is the problem, since that resistor brings voltage to the inductor. Am I way off here? a lot of my parts and tools are in storage, so I just wanted to see if anyone else had any ideas before I tear the thing apart. any help would be much appreciated!

[joegagan]

most of the time it is a simple miswire around the inductor. lots of stuff hooking up to just a few points, easy to run a few things wrong. check everything that remotely ties to the inductor.

[spaceace76]

yeah that's what I've been thinking. it must be the inductor since it doesn't want to wah. playing with it more today, I've noticed the inductor makes a popping noise when touched. it's not exactly micophonic, but if you hold it in one position it almost sounds like it changes the resonant frequency, but even when held in that position the effect doesn't work. perhaps I have a bad inductor? or maybe I installed it improperly. it would seem to my limited electronics knowledge that if the inductor is shorted then current won't flow into it, so after the 470k resistor i shouldn't get anything with a signal probe.

if i remember correctly, at one point the wah acted like a volume pedal (because of an issue with the 4.7µf cap). and i think that would mean the inductor section was working at the time, but it's been sitting around for a while, and survived two moves with me. I'll see if i can find my old stash of inductors for wahs and swap one in to be sure. thanks for your help!