Shruti-1 SMR4mkII no/very low Sound Output


I’ve got a problem with my Shruti-1 which I built yesterday.
The LCD powers up, the LEDs work and the potentiometers and the encoder are working too.
But the SMR4mkII doesn’t produce any sound.

What I’ve done yet:

  • measuring all voltages on the filter board: done, and successful.
  • measuring the signal at the OSC pin: done, but the filter doesn’t anything (cutoff and resonance doesn’t work.)
  • measuring the points in the output chain: at pin 5 and 6 there isn’t any sound, at pin 7 and 9 there is a very very low output.
  • checking for bad soldering points: done.

It would be great if you can give me some hints/help.

Please post a photo of your board. Check all solder joints near IC7 and IC8 (IC sockets and all parts around them). Check that the capacitors are soldered in the right holes.

Checked all solder points, no success.
Here the photo of my board. the Out Jack was desoldered, because i want to use metal jacks.
Still no sound output at Pin 9

You’re missing the v/oct trimmer… (blue box with a screw in it)

is this recommended for the output?

Nope, just stating the obvious :wink: Apologies.

This is necessary for the filter to work. You also have no output jack only the input jack. How did you test it without the output jack?

built the trimmer in. no success.
i test it with a probe on the out bridge.

did you connect the ground too?

when i put my trimmer in the first time, I had to do a decent amount of turning to get any noise outta my amp. It was 50 seconds of shitting bricks.

@shiftr: what ground?

The same ground you used when testing for the voltages… You can’t get a sound with just one wire. You have to connect signal and ground. I think best is to just solder the output jack and test it with that.

yes, that ground is connected.

So do you have signal at pins 3 and 4 and are they affected by the filter?