6-Switch Video/Color Problem

[kmarker]

I've been troubleshooting video/color problems on a friend's 6-switch and not having a lot of luck. After a few moments, the colors change and the sound becomes distorted. I'm using a cartridge that I know works. I've swapped out the power supply, RF cable, and TV/Computer switch box with ones that I know work. I've tried adjusting the color using the little adjustment pot, but to be honest, I may not have played around with it enough.

 

Any suggestions on the next step?

[Uzumaki]

Replace the 7805 voltage regulator. It's probably going bad. On a 6 switch console, it'd be on the lower left side of the switch board.

[A.J. Franzman]

Could also be weak contacts in the power switch, bad power filter capacitors, or bad polystyrene capacitors (the clear & silver ones) in the audio mixer. I would check the input voltage at the power jack and at the regulator to make sure they're very close to the same before replacing the regulator. If the voltage is much lower at the leftmost pin of the regulator, it's most likely a bad power switch, but could also be a leaky capacitor. Not only the large electrolytic filter cap, but also the small 0.1uF capacitor # C241 or C242 near the power jack was recognized by Atari as being a frequent failure point. The power switch can probably be taken apart, cleaned, and tweaked for better contact pressure. If this does not fix a problem of low input voltage to the regulator, replace the filter caps. If the voltage is good both into and out of the regulator, check the polyester capacitors. If they're bad, sometimes the audio will get better when pressing your finger on them.

Edited January 14, 2007 by A.J. Franzman

[russdog]

I don't know if anyone else has run into this problem or not, but one thing I've seen more than once that causes the symptoms mentioned is the 6532 chip (closest to the cartridge slot). It shouldn't get hot (it may get a little warm after extended use...but not scorching hot, especially not right away). Check to see if it's getting hot first - if not, then I'd recommend the other checks (the regulator, switches, caps, etc.). Fortunately that chip seems to be pretty easy to find online, or even at local electronic parts suppliers - just make sure you go by the number 6532, not CO-whatever that Atari part number is that's usually found on it. I've never seen the other chips (6507, CO10444D) go bad, except for one CO10444D that wouldn't respond to paddle inputs, but these are also pretty easy to find, and not too expensive (the CO10444D is a custom chip, so most electronic parts places won't have it, but there are several websites online that sell it, if you do a search for the part number).