Anamorph - limited repeats/feedback

[zwkelly]

Hi all,

I built the Anamorph and calibrated it nicely. It sounds great from TP1/2/3, wild self-oscillation, etc. However, when I go to use the pedal, I get 2 solid repeats and a few shadows after that. No self-oscillation, maybe a long ring after a higher note on a plain string, but nothing that takes off into madness.

I've gone over the PCB, checked all the parts against the instructions - I didn't utilize any mods or alternate filtering.

What I'm looking for? Either an answer or a good place to start with troubleshooting. Would the pot be the issue? Might something be touching? I haven't taken it apart yet (lazy and I hate knobs for splined pots) to check the beneath the board. I hope to do that with some better direction as to what I should do.

Thanks!
Zach

[madbean]

I would start with voltage measurements on the NE571 and compare those to the ones listed in the doc. For the audio path you'll want to verify that you do have 27k for both R20 and R21, and 100k for R45. I can't completely tell from your pic.

You can increase the amount of repeats by reducing the value of R45. So, if you are getting good signal at pin10 of the 571 but diminished repeats, I would socket that resistor and try lower values, like 47k downward.

[zwkelly]

Awesome. Thanks.

R20, 21 are 27K and R45 is 100K. Thanks for the starting points. I'm up for the challenge.