Atari 2600 displays no picture or sound
Hello all, I am having some trouble with my atari 2600. I connect it to my television with an rca to coax adapter. I am not getting any sound, and it is outputting some video, but it is usually just a series of lines, a black screen, or some objects flashing across the screen; it is different depending on the game that I try. My first thought is to replace the RCA cable. I am pretty handy with a soldering iron, and if it is something with the board, I would like to repair it myself. Any suggestions on where to start? Thanks!
EDIT: I have already cleaned the cartridge slot, and I don't think it is the RF module because I am getting some signal