I’m another user with this same microphone issue. My Mycroft Mark 1 just can’t seem to hear anything.
I admit he has been sitting on a shelf neglected for many months as nothing seemed to work on arrival. So over the holidays I found a little time to dig in and discovered that the updates had never been working. It seems it was stuck on 0.8.17 which had the update bug. I ssh’d in and did a manual upgrade via apt, but that seemed to totally screw things up.
Rather than waste time trying to work out what mess the upgrade had created, I copied the SD card image (mark-1_production_20171019_build-10) to a new 16GB microSD and booted from that. Still seemed to be deaf, so I left him alone to install any futher updates. That of course lead to him sitting there for hours saying “UPDATING”, apparently hung on something - but I couldn’t see anything in the logs. I used his control knob to initiate a reboot and he again said “UPDATING” for a while, but finally came back to normal - but still defa.
Now getting back to the microphone issue, I can ssh in and run
mycroft-cli-client and the microphone level shown jumps around a bit near the 600 mark, but the movement does not in any way correspond to audible noise. I terminated the various mycroft and pulseaudio processes, and then use
arecord -d 5 test-mic.wav to capture the microphone input. Playing it back with
aplay gave nothing, and copying the file to my PC and viewing it in Audacity shows just a low level noise. I uploaded a small WAV file and was successful in playing that back with aplay (as expected, because I can head Mycroft talk). I tried a second recording with me yelling at Mycroft and tapping on the plastic housing, but still nothing.
Looking inside and comparing thing to the schematic, I see a bunch of missing components (microphone bias?) but they also appear to be missing from the BOM. I guess I can get out the oscilloscope and check if any signal is getting to the preamp and then into the WM8731 codec. Beyond that, I’d assume a software issue of some sort. Any thoughts before I spend more time on this?