I have a monitor—likely CGA, as shown in the photo. Unfortunately, I don't have a CGA card to connect it to a PC (though I do have one with jumpers and a DB9 connector, so it might be configurable for CGA).

I connected it to a Commodore C128, but the image on the screen is rolling/wrapping. I can't seem to adjust it using the H-Phase knob on the back or the corresponding one on the mainboard. I don't have a schematic, so I don't know where to look for the cause of the fault.