Let's trace the HSync signal as it comes in. The VGA connector terminates at the neckboard, but a second set of wires takes the syncs down to the main PCB. First it goes into a WT8041 chip; it has no info but in an old post on Twitter, @
Foone🏳️⚧️ mentioned it's likely similar to the WT8043. This is an interesting chip: it detects the video mode so other bits of hardware can adjust voltages etc to match it, and it also conditions the sync signals before sending them on. This chip seems OK; the HSync/VSync that comes out looks as good as the incoming signals.
