CD-i member frankers138 revised his CD-i 220's RGB board for compatibility with HD Retrovision cables by utilizing an onboard 9 pin mini din and required components. HD Retrovision is specialized is high quality cables that preserve the quality of your console output to fit on modern HD tv's. HD Retrovision: "Our mission is to preserve gaming history and improve the retro gaming experience. We're working on products that allow gamers to play their old consoles without modifications to the original hardware". Consoles like SNES, Genesis, Saturn, Neo Geo, Wii, Playstation all have specific HD Retrovision cables. CD-i is not included yet, but with hardware modification it fits to the cables very well and the video output is better than the standard RGB output of this CD-i 220.
The 9 pin mini din can be mounted on the CD-i board and connected to the current RGB connection on the PCB board:
With the mini din 9-pin to component cable by HD Retrovision you can create a CD-i YPbPr cable to have the best possible video output:
The output is very crisp, in 240p (be sure your TV supports this output). Below for example Super Mario's Wacky Worlds and Plunderball on CD-i:
[Thanks, Frankers138, Oshpark]