Jail bars in rgb are common. The steve in the mods forums seems to have figured out a fix for the jail bars. My duo's output looks great despite the jailbars in the back ground. make sure its not your tv or a setting that needs to be adjusted. If not, it can be fixed. we have members here that can make it sparkle
If it were just the banding maybe I could live with it, but honestly I think the banding is fairly bad along with some other oddities in the picture. It's the only console I have that's been modded for RGB while all the others I have hooked up this way are consoles that output RGB natively. All those other consoles (Sega CDX, Saturn, Dreamcast, SNES) exhibit very little if any banding, the colors look good and they are overall really good images. Just not sure here if the RGB Mod needs to have some adjustments or what. Heck I'd even forgo the RGB right now and use the composite output since most of the Turbografx/PC-engine/DUO systems I've seen in the past have pretty decent composite output but even the composite on this one seems much worse than normal.