No sound / no output signal

Bonjour,

Je viens de finir le montage de mon shrutthi et je n’ai pas de son. J’ai pressé le bouton 1 pour 2 secondes. J’ai vérifié les alimentations. La carte logique semble bien fonctionner et l’affichage est bon. Toutes les fonctions semblent répondre normalement.

J’ai fait deux mesures avec l’oscilloscope j’ai un signal sur J4 à coté de l’alimentation : signal carré de forte amplitude (5V), puis un signal de forme triangulaire sur la patte 1 du TL072 (de mémoire autour de 1V). Je n’ai rien d’autre comme signal.

Qui peut m’aider?

Hi,
Sorry for my bad english. I juste finished my Kit and it seems not working propely. In fact, the controller seems to work OK but there is no sound outside. With a midi Keyboard connected or with de fist button olding down for 2s.

I got 2 signal on my scope : on square a the J4 connection, and some triangle at the input 1 of the TLO72. Nothing else. I’m used to build some fine audio system with valves. For me, this kit is very very tinny and I’m a bit lost.

Who can help?

How can I be sure that the control board is very OK?

Where do I need to chase? I’m very lost.

What is the amplitude of the signal on TL072 pin 1?

Bonjour
Presque 3 carreaux avec .5V/Div Je mettrai bien la photo mais elle est trop lourde pour le site…

Voila, la photo

I saw the picture you’ve posted on FB. Signal on TL072 pin 1 is OK - PWM signal from the oscillator with mild low-pass filtering.

Please post pictures of the signal on:

  • IC7 pin 1
  • IC7 pin 7
  • IC7 pin 8
  • IC7 pin 14

IC7 pin1

IC7 pin 7

IC7 pin 8

IC7 pin 14

V/division?

Could be correct, though I’m a bit worried by the DC offset.

Now, could you post high res photos of your board?

Hello,
You can see the V/division on the pix It is the scale on the red left button. There are very little signals. I though it was noise…

Please post high res pictures of the boards. Likely to be two swapped resistors or a missing solder joint somewhere in the filter circuit.

I did it on your FB page. Sorry about that 'cause is very more convenient to do so. Then you have the best pix res that I can send to you.

Thanks for your help.

I soldered the opt resistance. Am I did right?