HI Guys, been in the videogame repair business for 15 years, but never figured out how to repair the Model 1 Super Nintendo that has AV Problems, so I just kept storing these up, so I am fed up with all these defects here, and need help to figure out whats wrong with them! and no, its not cap replacement, Ive done enough cap replacements on my snes to know this is not the problem!. Ok so in a nutshell, all of them are Generation 1 SNES Consoles, the one with the removable soundboard, all of them work fine with RF Hookups but if you use an AV Cable a lot of jitter can be seen (And you can hear the sound ok) So I guess the snes has 2 video controller chips, of some kind, that outputs the video one thru RF and the other thru RCA. I need to know which chip is it! and its damaged on all of my 50+ consoles, (95% of generation 1 snes that i get i trades have this damn problem).

I guess is a progressive damage that occurs over time to a particular chip
Some Consoles start showing dark image on RCA, normal image on RF
Some Consoles start showing dark image on RCA then Starts to Scroll and image fades, normal image on RF
Some Consoles start showing black and white jittery image on RCA, normal image on RF
Some Consoles start showing black screen with some lines waving (No Image) on RCA, normal image on RF

Full Cap Replacement has no effect

any feedback is greatly appreciated. Thanks!