It's almost like the guns are not tracing over that area. I'd say that means there could be a HV related issue since the HV is there to ground spent electrons and if the guns can't hit the phosphor there then there must be a "cloud" of electrons in the way. The shape would lend itself to that explaination anyway.
I'd say rather than the HV itself being at fault though, it's more likely that the tube never had proper aquadag application in that area.
If it goes away when a game loads though then I've no idea. A different resolution would not affect that. If you can see it all the time then your tube is done for. Either way the phosphor is not getting hit in that area.
Maybe a video would help diagnose it further? I'm very interested in what this could be.
Edited by RetroRepair (04/28/12 01:50 PM)