Unfortunately the colours are slightly messed up. It's hard to describe, but there is an odd tint (greenish?) on some of them. Pure white is non existent. Some are just downright different - eg red seems orangey, yellow-sickly, blue-cyan, dark green-light green and so on.
Quick example from the Amstrad core (I've tested several cores, also SNES etc, and it happens on all of them).
- IMG-20200624-195653.jpg (375.17 KiB) Viewed 8276 times
Here's the real Amstrad
- IMG-20200624-195703.jpg (335.03 KiB) Viewed 8276 times
It's really hard to take a photo of CRTs in action so it's not 100% accurate - for example the white on the border of "1942" logo in the first photo is not really white but green-tinted. Still, you can get a rough idea of main differences. I have tested it extensively, with various TV colour settings. My .ini values are okay as well I think (composite sync=1).
Here's the odd thing: this happens on 2 of my Trinitrons (both medium-old, probably end of 90s or early 2000). It does not happen on 2 others though (one really old, one pretty new). So that's rather puzzling. Also, it's fine on a PC CRT VGA monitor. And exactly the same thing happened with my ZX-Uno FPGA board, also from VGA output. Both boards are connected by dedicated cables from experienced builders.
I also have numerous other systems (real and emulated) connected to these TVs via RGB and have never seen these odd colours. So, it's a little mystery, maybe somebody has an idea as to what could be the cause here.
It seems that this definitely is the issue with CSync either way, so at least I know what I'm dealing with.