VCO and VCF trouble

Hi,

i have some problems with my Anushri built from a complete kit by MI.
The main problem is the resonance control, even at the lowest setting, there
seems to be quite a lot of resonance. Furthermore, the pulsewidth isn’t at 50%
at the center position. I also experience tuning issues, but I guess I should
figure that out after getting the filter and the VCO working correctly.

I already resoldered all connections. The voltages I measured appear to be
correct.

Unfortunately I don’t have a better camera at hand right now, but I can try to
make better pictures of certain areas if needed.

Mainboard:
http://www.brechpunkt.de/paste/Ne0TLtGx.jpg
http://www.brechpunkt.de/paste/OhCS5MPp.jpg

Square derived from Sawtooth at 50% PW setting:
http://www.brechpunkt.de/paste/UCBl6J97.jpg

DC corrected Sawtooth:
http://www.brechpunkt.de/paste/ZeCYNc8B.jpg

Sawtooth Core:
http://www.brechpunkt.de/paste/6SDXZAk8.jpg

Square Wave with Filter fully opened and 0 Resonance:
http://www.brechpunkt.de/paste/p3WlskZu.jpg

Thanks for your help in advance :slight_smile:

Are you sure you have used the right pot (100kA) for the resonance control?

I am not 100% sure. Is it possible to measure the pot in circuit? (with the control board disconnected from the mainboard)

Yes, this is possible (quite an exception!). You should measure 100k between both extremities.

It is only 87k

Hmmm must still be good…

Can you check the color codes of R51 / R52 / R53 / R54?

The resistors are 470, 4.7k, 4.7k, 33k, so they should be correct.

What about the DC corrected sawtooth wave? Is it correct, as it appears somehow clipped?