Filter Resonance Issue on CEM3379 board

Hi there

My first post, sorry to already bother you with my problem.
I finished soldering my shruthi-1 (with cem3379 filter board) a few days ago, everything worked nicely from the moment i plugged it in for the first time. However, after playing around for a bit (and looooving it!), i noticed that the resonance control had somehow stopped working. It definitely worked in the beginning, but now it’s stuck at a zero setting and the filter can’t be brought to resonance anyhow, whereas the cutoff control works nicely…

Any idea if this is rather a hardware or a software problem and in either case what i can do to eliminate it?

Thanks a lot!

It’s unlikely to be a software problem…

First, and just to be sure: when you mean “it’s stuck at a zero setting” you mean that the LCD always shows “Res: 0” even when you turn the second pot. That would be very unlikely… Your problem is that the resonance setting changes on the display but nothing changes in the sound, right?

If you have a meter, check the voltage between GND and the Q> pin on the digital board. It should vary from 0 to 5V when you sweep resonance from 0 to 63.

Next, check the voltage at the pin 7 of the CEM3379. It should vary from 0 to 2.6V when you sweep resonance from 0 to 63.

It’s probably a bad connection between the two boards, or something near the 68k/47k/10k resistor trio responsible for resonance CV scaling and filtering.

Yes, my problem was that the sound did not change even if the display setting changed, and yes, the problem was a bad connection between the stacked headers. Looks like i soldered the male connectors a bit skew…

Well, everything works fine again… thanks for the fast reply!