130XE Audio Noise/Buzzing with Cartridge Games?

[RCA1802]

Hello,

I have a 130xe which I have added a Sophia, Ultimate1MB and a UAV to and they work great, however I have noticed something odd with this machine, when I play cartridge games the audio is noisy and full of background static. I replaced the original ROMs and removed the Sophia board and it had no effect. I checked all my solder joints and I don't see anything damaged or cracked/lifted. I thought I might have damaged the GTIA when desoldering it because it got REALLY hot but it seemed to work fine after. I also replaced the audio opamp. I was messing around with my new Fujinet today and I loaded Donkey Kong from an .atr and it didn't have any static! I tested Star Raiders and Donkey Kong both from cart and still had static... I've checked all the traces and contacts and nothing seems to be amiss so I'm at a loss as to what the issue could be.

 

Does anyone have any ideas?

 

Thanks!

[Doug_in_NC]

Did you ever find out what the issue was? I have a similar setup, (though no UAV) and the same issue. I'm not sure that my audio issue has any connection to these mods though. Could just be a coincidence. I also changed out the audio op amp today (bought a pack of them from Amazon and tried half a dozen just in case) and it had no effect at all. I guess the Pokey could be damaged, but the impression I get is that the problem is a lack of amplification. I'm going to change out the Pokey tomorrow for one I have on a dead board and see if it makes any difference. 

[+Nezgar]

I'd take a guess that with all those upgrades at least the top RF shield was removed, and is now leaking interference into the audio signal...