Atari 2600 outputs random patterns on screen when turned on

I recently got my Atari 2600, i cleaned it and reflowed most components, but even after that, cleaning the games and everything, as well as the cart port, it gives weird patterns on the screen such as lines in different colors, or just grey bars, it’s different for each game and I really need help with it, should I get the coaxial to RCA adapter?