Intellivision with horrible audio buzz

[livingonwheels]

I recently received an RGB/ S- Video/ composite modded Intellivision I console. Both composite and S-Video have horrible auto buzz/hum. Not nearly as bad via RGB. Only way to "diminish" the audio buzz when using composite or S-Video is to make sure the RGB Scart cable is connected simultaneously (Scart cables sync connection must be connected for this "fix" to work). So at this rate, the only way I can use composite or S-Video is through a monitor with a RGB connection also. I purchased a ground loop adapter hoping it would fix the issues without the need for RGB to be constantly connected, but it didn't help. Here is a short 10 second clip of the noise:

https://vimeo.com/812925594

Edited March 29 by livingonwheels

[+-^CrossBow^-]

Interesting you mention this. I've got a client complaining of something similar from his Intellivision 2 console. However, it is only the RGB through a 9-pin and doesn't have any other of the other outputs installed. What was odd is that the same hum wasn't present through my setup and that Intellivision II wasn't wired up any differently from any others I've done and haven't heard any issues with from anyone else. So I'm not sure if it is just some units are noisier than others or what might be happening since in the instance of the one I do know about, I wasn't able to reproduce it.