No filter cutoff 4PM

1st I checked around IC5, resistors and solder joints, and it looks well. Shruti settings on 4pm filter. But it seems I got no response on cutoff when tweaking the pot, I can’t hear sound change. What this could be?

What is the voltage on pin7 of IC2 with cutoff set to 0? cutoff set to 127?

ic2 on digital board or filter board? to probe pin7, red tester pole to pin 7, and black goes to pin8?

On the filter board ; and black probe to a ground point.

But even before doing this, try probing the F> point on the digital control board. Should go from 0V to 5V (or less because of filter tracking) when you sweep cutoff. You could also check that the two boards are correctly connected.

Have some patience Olivier… what’s the F> point? In case I want to probe the ic2, I’m wondering how I can do that, as i have the 2 boards connected

I found it…

I have 0v on cutoff 0 and 2.44v on 127

That’s on the F> point right?

pin7 of IC2 should go the other way round… less than 0.5V when cutoff is set to the maximum value ; above 2V when cutoff is set to the minimum value.

yes F point.

I have 2.18v when cutoff is 0, 1.19 at cutoff 127

Depending on which note you played on the keyboard to trigger the note this sounds OK.

Next step is to probe the signal at the 4 filter stages:

What can you hear here? Any filtering happening?

to probe that, I need to ground a jack sleeve and probe the resistor points with the jack tip, and hear the sound. is that correct?
btw, i connected the beast leds, “in blinking eyes on the front panel with alternating pattern”, but they don’t light up at all.

Try the mod wheel and turn the resonance up high as well. They tend to come on then.

Now I know why: I cut the 1x8 and 1x6 connectors too short. pressing where the boards connect, the cutoff now works. I have no spare connectors to replace though:-(
Eyes/leds still not light up, but this could be for the same reason, boards not well connected

@pichenettes
all seems working but the eyes/leds. I tried a couple configs as described. I have +5v on the led near ic8. the other is 0v

What is the resonance setting on the control board? The eyes should not be on all the time ; only with some specific combinations of settings. High resonance is one of those, the other ones… I’ll let you find them!