Help with looper feedback pedal - FIXED

[Toddak]

Hello all.

So I've been working on two of these pedals: http://diyshoegazer.tumblr.com/post/3042080186/diy-guide-to-feedback-loop-pedals

And weirdly one is working fine, the other is not. I'll admit, usually this is the point where I give up, but given the simplicity of this circuit then it should be a perfect time to start learning! So I joined the forum and here I am.

So, what doesn't happen. When the pedal is off, audio flows straight through the pedal fine. When the pedal is engaged, the light goes on, but the audio is dead, nothing is coming through.

I do have a multi meter which also has a continuity tester, so I've been poking around between the working pedal and the non working pedal, but I can't seem to find a difference.

But! Through some playing with the pedal I have found a difference which will hopefully be some use in trouble shooting. When the pedal is off, and the switch is on, the pot will affect the volume of the audio flowing through the pedal. Full turned one way it will cut off all the audio, then with a subtle adjustment if feels like it goes more or less to full audio, well before I'm finished a rotation of the pot.

I'm guessing it may be relatively obvious, but I'm hoping I can learn through the forum.

Any ideas would be greatly appreciated

[ElectricDruid]

With such a circuit it can almost only be a wiring mistake. What you describe with the pot changing the level makes it sound like the pot might be shorting the signal to ground.

Rather than testing the continuity, I'd check that *everything goes where it's supposed to*. Somewhere in the one that doesn't work, something is wired wrong. I'd start with:

1) Common ground is on the right connector of all the jacks?
2) Wiring on the back of the 3PDT is correct? (this is a classic error and easily done)
3) In/Out are the right way around? (another classic)
4) Likewise Send/Return

Good luck!

Tom

[Toddak]

Hey Tom,

Thanks for the advice! I followed your directions and the 'everything in its place' idea was where I found something wrong. While everything was wired correctly, the tip of the return jack was just touching the metal enclosure (should have drilled the wholes a few mm closer away from the edges!).

I spun it around a little and it's all working fine. Probably another rookie mistake! But thanks for the help, muchly appreciated!

[PRR]

> the tip of the return jack was just touching the metal enclosure.... Probably another rookie mistake!

It is one of the most POPULAR "rookie mistakes".

Everybody has grounded something to the chassis accidentally.

The take-away is to learn to expect such things, and look for them.

Then you can gradually graduate to "better" mistakes. (I've grounded the wall-power live-wire with a case screw.)