[PaulS]

I am working on a dunlop JH1 wah and have come to a point where I am beating my head against the wall. When you click on the wah and rock the pedal to mid position it starts to feedback and if you go all the way back to the bass position it starts to howl. Now I have changed the pot , a brand new Dunlop hot potz, have tried differant inductors, changed about every cap and resistor on the board. Changed transistor pairs twice (5089 first time, 3904 the second time) . Using an audio probe the signal comes through the input buffer ok but on the 1st stage tranny it starts to howl. Any ideas here would be greatly appreciated. I am missing something. :thanks5qx:

 

[Slidewinder]

Just out of curiousity, where is your wah in the signal chain?
Have you eliminated all other factors outside of the wah, which could cause howling?
Also, when you changed resistors, or caps, did you use different values, or just replace the components themselves?

 

[keefsdad]

Plugged in backwards?:confused-smiley-010

 

[sysexguy]

I've done that!!!!!yes that will cause the howling

 

[PaulS]

Ok to the first question, it is the only thing in the signal chain as I am trying to trouble shoot it, secondly I am troubleshooting using an audio probe at a very low volume level. When I replaced components I have left them at there original values that were in the circuit. No it is not plugged in backwards, I have made very sure of that. It does not feed back at the top end of the pedal just the bottom. I have replaced and tried different inductors and pots from good pedals ( known to be good working parts) . About ready to take it out back and put it out of it's misery......