Experiencing a sync issue of some kind with YPbPr on a 15khz CRT?

[X-pert74]

My MiSTer seems to have a sync issue going on via YPbPr. Not sure what's causing it exactly, but I only started experiencing this within the last few days or so. Experienced this with the GBA core's start screen, with Rusty on the ao486 core (running at 15khz), and with Mega Man 2 in the NES core. It causes the top of the screen, or the top of certain images to be distorted over to the left, and I'm not sure why.

This does not happen on original hardware, as this video I recorded demonstrates (look at the top-right corner in particular). So, that tells me I need to change a setting on my MiSTer. But I'm not sure what exactly would fix this. Does anyone know?

(I already tried flicking the sync-on-green switch, but that made it worse, so that's not related to my issue. I also didn't have this problem the first time I loaded up Rusty, but when I tried it again a couple days later, that's when this issue started happening)

(first pic is of the GBA core's start-up screen. Second and third pics are from Rusty in the ao486 core; third pic is especially bad because the art causes the girl's hair to distort, and point toward the left of the screen)

IMG20240505194607.jpg (2 MiB) Viewed 893 times

IMG20240505195941.jpg (1.76 MiB) Viewed 893 times

IMG20240505200047.jpg (2.29 MiB) Viewed 893 times

[FoxbatStargazer]

When using YPbPr there shouldn't be any kind of sync with the SoG switch "off" so its interesting that it can make things worse.

Many people have had specific TVs having trouble with Mister sync using YPbPr. Aside from avoiding the cheaper I/O boards from Alibaba, creating your own SoG circuit, or getting a different TV, not much you can do.

[KennyL]

Does it happen with svideo or composite? Try different cable?

[X-pert74]

I have been doing a lot of testing for well over a day now. I've determined that this sync issue seems to apply to newer-updated MiSTer cores, but not older cores...? I tested a bunch of old GBA cores here

The 2022-08-12 GBA core looks okay.

the 2023-08-06 GBA core looks okay.

the 2023-12-11 GBA core does not look okay. Same applies to all the cores since. It's not just the GBA core either, as the ao486 and NES cores had this problem too. To confirm that, I tried out some older NES cores too just now -

the 2023-02-23 NES core looks okay.

the 2023-12-04 NES core does not look okay. Again, the issue seems to start with a core release from last December. Really bizarre...