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WIGGLING 'LITE' IN GUEST MODE

Ripples fine except no resonance
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Ripples fine except no resonance
aragorn23
Hi all,

I built a ripples a little while back and it's all fine expect for the resonance. I've reflowed, but the pot and cv in for resonance do absolutely nothing. Any ideas what IC's, etc. I should be troubleshooting?

Thanks!
thermionicjunky
Does the VCA function?
aragorn23
thermionicjunky wrote:
Does the VCA function?


Yup, the VCA is fine, as is the freq in CV and all the outs. It's just the resonance :-(
hox3d
Resonnance amount is set by the second OTA labelled IC4 in the original schematic.

Maybe it is always closed for some reason?
I'd suggest investigating around that, or the circuitry that controls it.
aragorn23
Thanks! I'll have a peek at IC4 and surrounding circuitry.
cygmu
To be explicit, the control circuitry is IC5C and Q1 and the associated resistors.

You could take a look at the voltages at both ends of R26 as you vary the resonance knob. One end should be 0V at all times, the other should vary fro 0V to maybe -9V. Also investigate IC4 pin 16 -- should be fairly fixed at -10.8 or thereabouts.
aragorn23
Thanks, this is very helpful!
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