Below is a picture of my RGB modded Intellivision’s sync pulse on my ancient oscilloscope.
I set the scope so that the vertical was .5v per CM (between each line) and 0 volts was at the bottom
Here is a picture of the calibration on the scope:
Then I set the time (horizontal) to 5 uS while looking at sync signal:
I am not an expert on video so please let me know what else it would make sense to look at.