Shruthi 1 No response from Filter and very quiet


My first test reveals no response from the filter parameters. The voltages on the filter board seemed to test OK during the build. Any advice on what I should be checking? It’s also very quiet.

Any help would be much appreciated.



Which filter board? If it is the SMR4 mkII, please trace the signal path as explained in the build instructions.

Is it a SMR4? Do the signal test in the trouble shooting section of the build page. You could also post pictures of you board.

I think Olivier is 2 minutes closer to the server :wink:

Thanks for the swift response. It is the SMR4 mk II from the kit. I didn’t see the troubleshooting section but did test all the points highlighted in the photo. Let me look again…

Yes do look again… It’s not voltages you will need to test for this but signal. You will need an Oscilloscope or an audio probe for this. A jack cable cut in half can function as an audio probe.

OK. I get what I think is an audio signal from point 1 but nothing from point 2. I desoldered the IC mount, tried a new chip in IC2. I then refloated all the solder points surrounding (which looked fine) but still it’s the same. I know you must really hate these kind of questions but I’d really appreciate it if you could suggest my next step. I guess I try replacing the 4.7uf caps? Thank you for your help so far!

Oh - no swapped components either - I checked against the photos.

I’d say post pictures of the front and back of the board…

Thanks. Here are some pics

And the reverse…

R12 (the 330kohm resistor) is missing.

Ha - well spotted! - That’s all it was. I was concentrting so hard on the audio signal path I missed the obvious. Works great now. Thank you all for you help. Victory candy time :slight_smile: