Atari Heavy Sixer Issues.

[MadMan]

Keep messing with the chips, contacts probably dirty as hell and not mating well.

[Laserdisc]

I have no idea whats up with it but at this point I have surgically cleaned every contact in it and it plays great aside from a loud hum laid over the audio.

[RetroHacker]

The main filter cap is failing/has failed if you're getting a loud hum. Try paralleling another cap of suitable voltage over it and at least 1000uf and see if the hum goes away. Also possible your voltage regulator isn't working right, double check that it's actually putting out clean 5V

-Ian