Anushri Sub (Solved)

Hey folks,
after getting together my anushri and playing around with it a little - everything seems to be fine (midi now working fine). My first diy-project…but I’m worrying a bit about the sub. Changing the sub level does no effect and changing the mode (DCO, -1 octave, -2 octave) neither. I’m asking me now where do I have to take a closer look at? It sounds a bit to me like the sub is always on -1 octave at the maximum. If it helps, I can post photos of the soldering or mp3s of the sound it produces…I have comparised the sound with Oliviers demo of the sub on the soundcloud.

The main board looks pretty clean but maybe a bit light on solder in spots. Nothing is jumping out at me but it’s always a good idea to remove the chips and reflow all joints and add more solder where needed.

If you sourced the parts by yourself, then you can check if IC 11 is a CD4024 and not a 74HC4024. That was a problem with my Anushri with almost the same symptoms you described above.

No, I didn’t source them by myself. It’s a CD4024…

Do you see any obvious mistakes? The octocoupler is now the right way round.

Also you said you got your midi working, but is the chip by your mini connections oriented correctly? It’s hard to tell.

Edit…oh i see you mentioned that. Sorry.

First, you have to determine what’s broken: the sub-oscillator or the path from the sub-oscillator to the mixer.

Probe pin 1 of 4024. You should hear the square oscillator.

Pin 12 should be 2 octaves below

Pin 11 should be 1 octave below.

Is that OK?

pin 1 is sawtooth, pin 11 2 octaves below, pin 12 1 octave below…pin named 1 is on the bottom in the left corner, anti-clockwise counting?

Hey sorry, actually that’s the sawtooth that should hit the sub. So we’re fine here.

Your waveforms look nice, CD4024 is correctly doing its job here!

Next steps:

  • Check the soldering of J6 (the stacking header on the main board)…
  • Check the soldering of J15 (on the control board) - maybe a short between pin 1 and 2?
  • Probe the pins of the SW7 switch (check the schematics).
  • Check that the right pin of the R19 (sub volume) pot has the correct signal depending on the position of the switch.

I think I check the soldering again tomorrow… a little more solder can’t harm…
So far: the signal reaches the J15 on the control board. changing the sub level variates the volume at the following point (see drawing) but only in the middle position of the SW7. If it’s -2 or DCO, there’s no signal… I think there’s something wrong with the SW7 switch or the soldering on the control board?

There was no obvious short. Probably a cold solder joint…resoldering helped solve the problem. Thank you guys!

Woohoo. Congrats!