P4 voice card troubleshooting

Hi guys,
I’ve build a P4 voice card, but when i put it on my ambika i’ve good sound, and when i want to make the vcf tuning no sound.
I imagine there is a probleme but perhaps somebody know where is it.

Are the DATA / NOTE LEDs on when a key is pressed?

Hi pichenette
All the led work good, and i press the do 3, and when i make the same operation on another voice card it works good

And i ve a great sound when the filter is very open, but when the filter is cut off i ve noise and i make the vcf tuning ( like you show on the diy page) no sound

So no resonance you mean? Probably a bad solder joint. Could you post pics of your board?

Try tracing the audio path…

Oscillator out is on IC6 pin 6.

The various outputs of each filter stage are:

  • IC3 pin 1
  • IC3 pin 7
  • IC5 pin 7
  • IC5 pin 1

Thanks you, i try it and this the pcb

If i listen the pin 6 on IC 6 i’ve nothing. Is it normal?

No. Do you have sharper pictures for us to check the quality of the solder joints and the parts values?

This is it

Little precision : when i play a note and the filter cut off is on 0, i’ve a buzz

And the buzz diseppear when the value is 70

Are your other voicecards ok?

yes on this ambika i ve 2 SVF and 2 P4 and i ve another ambika who have 6 SMR4.

and all the voice card are ok just this one doesn t work

Have you tried swapping parts (MCU, DAC), with other working voicecards?

oh no, what is the reference of DAC and MCU please

IC6 and IC7

ok thanks i ll try it

Ok i try it but it doesn’t work. And when my finger is near the IC 4 and 5 a big buzz appear.
I try to change them but it doesn’t work.
I don’t understand:(