CGS29 producing high frequency oscillations

GeneralBigBag · Joined: May 21, 2007 Posts: 14 Location: Vic, BC

(duplicate thread on muffwiggler)
I think I have this isolated to the wave folder - it produces a high freqency tone as well as passing signal (and folding waves). Other than that, I haven't the foggiest. I've checked component values and orientation and it seems to be alright, the only thing for sure is that I have not added the smt decoupling caps to the build.

Any suggestions or advice would be most welcome.

tommi · Posted: Tue Feb 08, 2011 3:26 pm Post subject:

I am not sure that othis board needs smt caps, maybe only on the 2nd version?
To be honest I am not sure wich version i have built..
Anyway I have some noise too, even with no signal on the input. Tomorrow I'll try to look deeper.

GeneralBigBag · Joined: May 21, 2007 Posts: 14 Location: Vic, BC

It turns out that I'd cut a trace to ground in the development area, so some of the diodes were floating. I wired a jumper and the thing works perfectly now. I suspect you don't need the caps, but they don't hurt (I used through-hole ones, which was less fiddly).

tommi · Posted: Wed Feb 09, 2011 11:41 am Post subject:

Nice, so now you have a working module! Very Happy

Today i inspected my board and i discovered i had mounted a 0,47mF cap instead of a 10mF on the +V rail. Now i changed it with a 10mF one.
My PCB version is the 1.0 rev 2 so no smt caps on it, but i kludged some changes of the 2.0 version, like the limiting zener diodes on the grinder out and on the PWM CV IN.
Now i am gonna do some test and then i'll report my results..

msprigings · Joined: Jan 16, 2012 Posts: 7 Location: Virginia

I'm getting some high frequency oscillatotion from the Grinder section. I can't really tell if it's working as intended or not. My guess is no. I tried multiple LM358's as outlines in the instructions. I have the v2.1 board