I'm not a super-expert of oscilloscopes but I used several Tektronix (both analog and digital.)

I have a [Hantek DSO4254C][1] and I'm not able to get it to trigger on a sine wave coming from my board. The signal has a frequency of 300 Hz and an amplitude of about 3.6 Vpk-pk. CH1 is set to DC, the trigger is set to rising edge and automatic mode and the trigger level is about one half of the signal:

[![enter image description here][2]][2]

The waveform bounces around the X axis continuously, so I tried to set the mode to manual and I discovered it does not trigger. If I manually force the trigger, every time the waveform is  shown in a different location (like the auto mode does).

Why is the trigger not triggered? What other settings should I tune?

The only way I found to get a "quite" stable waveform (even if not perfect) is to use the slope type of trigger. That means I have to define two thresholds. That seems to be overkill to me for such a simple signal.

  [1]: https://www.hantek.it/oscilloscopi-da-tavolo/110-hantek-dso4254c-oscilloscopio-250mhz-a-4-canali-e-generatore-di-awg.html
  [2]: https://i.sstatic.net/sDh3h.jpg