Atari 4-switcher with no picture. What could be the culprit, what to check next?

[CapitanClassic]

I just bought a used Atari 2600 system. It only came with one game, so I cannot troubleshoot the game itself being defective. I also cannot seem to find a relevant thread that has the same issues. I have cleaned all the contacts and switching the power on normally results in a diagonal white line that scrolls across the screen. Every once and a while I get colored bars (assuming something altered PF0-PF2 or the player sprites.) Sometimes I get a blank black screen, so it is sending a signal to the TV. Very rarely do I get a screen that could almost look like Combat playfield (but it definitely isn’t). Also, should Combat be missing a trace on the front (Pin 8/Pin 5? Or maybe the backside is pins 1-12, so pin17/pin20).

 

What is the next thing to troubleshoot with these symptoms? Do I have a bad TIA or RIOT? Do I need to do a recap sooner rather than later to prevent any exploding capacitors?

 

 

 

[BioButt]

I have a similar problem. I have replaced the caps and the power regulator (reads 5.0 VDC on the output but 15 VDC on the input, across the 2200 uF cap and the power supply). I even replaced the power input jack (got the kit from Console5.com).  Not sure what it is.   Doesn't look like anyone has responded with ideas

[+DrVenkman]

Get another cartridge to test with - that Combat doesn’t look right (though my several copies are upstairs at the moment so I can’t compare). But the fact that you’re getting a picture at all eliminates lots of components from immediate concern. So get a known-good cart from a friend or local retro shop to test with and then go from there.