I measured several things, turns out the trimpots might have broken now, but that doesn’t explain the behavior for me, because it was the same when i first switched it on as it is now.
I have an LM4040AIZ 5.0 (as explained over here 1222 Tuner VCO Module fixes/improvements - #42 by Steve) and L7808 CV instead of the 7805, as suggested.
I get these Voltages at the moment,
R42: 4,98V & 11,80V
CNTR: 1: 11,80V - 2: 5,61V – 3: 5,61V
And something completely out of place, 1: -7,12V – 2: -7,29V - 3: -7,29V
at the TRK Trimmer.
The Octave Switch by the way, is completely fine. Pins go all the way from 0V to 4V.
TP1 Voltage is good, i had something between 3,97V and 4,01V.
I don’t know, if you say the randomness can’t come from the Arduino, because it only picks up the sound and displays it, but doesn’t switch anything then i have no idea what’s actually wrong.