I think this HDMI to VGA adapter may be the issue. If you can crack it open, you can know for sure what the chipset is. From what I can tell both of these statements are true:
- Your TV works with everything you plug into it, except the MiSTer when direct_video=0
- Your TV never works when direct_video=1 no matter what modeline/resolution you try for any core
This tells me two things:
- There is likely something wrong with the scaler FPGA code that mucks up the video signal in some kind of way that makes the device doing the HDMI conversion do some clean up of the bad signal. I had the same issue when I was testing one of the bad component converters. I plugged in the direct_video=1 Menu timings into the scaler. The same timings worked with direct_video=1 but did not work with direct_video=0.
- The electronics in your TV are fine. The HDMI to VGA (or less likely, your ini settings) is the issue. I would verify the chipset of the adapter and buy another one with the AG6201 chipset.
Also I think a scrolling has to do with the sync signal. You could try adjusting the resistor value with a potentiometer and see if you can get the scrolling to stop (in your VGA to RGBS chain).