I just got the TCL Roku 4K HDR 6-series 55’ TV. I have the standard (original) Wii from way back and my kids and I play it all the time. I purchased and installed the ONN Composite AV Converter and a 4K UDH HDMI cable to connect the converter to the TV. The sound is fine but the picture is atrocious. It’s like a very thick layer of fog is covering the entire screen, instead of the crisp bright picture I hoped to have. Since I’m connecting older technology to the newest TV technology, should I have purchased a cheaper/plain HDMI instead of 4K? Has anyone else had this problem? That Wii provides much laughter and great memories with my kids. I really need it to work. Any ideas?
From your description, it's hard to be sure if this is just the common result of running a device from the days of 480i on a 4K display or there is more going on. I did see a light review of the converter on youtube, and that guy was unimpressed saying the colors made it hard to see, so maybe a different converter would be better. You could also try your TV's picture controls – hopefully they are separate for each input.