I changed the value for ocr1val from 3 to 0, but can't see any change in output signal. I'm checking the signal on pin 9 using my DSO (UNI-T UTD2042C). Yesterday I was just looking at the waveform, today I'm using the built-in measurement capabilities. Turns out that the clock I'm getting on pin 9 isn't 125 Hz but actually 104,1Hz.