VCO coarse and fine weirdness

smartattack · Joined: Jan 07, 2016 Posts: 5 Location: New York

I just wired a YuSynth VCO (THANKS Yves!). Very excited to see waveforms that look and sound good. One thing:

Both the fine and the coarse knobs are tuning wildly - like a 20-30 degree turn is sweeping the whole audio range, and coarse and fine both have the same sweep. I looked at the wiring for v+/v- header and for the coarse/fine wipers and it seems okay. I double checked the two pots, they are 25k linear. I doublechecked the 3M3 and 270k resistors for fine and coarse - they are good. I'm not sure where else this could be going wrong?

AlanP · Posted: Thu Jan 07, 2016 8:57 pm Post subject:

It'll be one of the resistors around that area, and the first opamp they go through (around T1 and T2), or the resistor going to the current mirror (22k, forget the number of it.)

smartattack · Joined: Jan 07, 2016 Posts: 5 Location: New York

Wow, silly. So it turns out I inverted the 5 pin connections so coarse and fine were going to the v/oct jacks and vice versa.

All working now. I love these YuSynth modules - they are amazing. Thanks again, Yves!