Here is what I have tried to no avail....
I verified the outlet is grounded using a outlet circuit tester. Also, the UPS will indicate if the outlet is not properly wired.
I connected the pc directly to the outlet, with and without an additional grounding cable.
I connected the pc through the UPS.
I connected the pc to another outlet.
I used a USB extension to extended the mj 6 feet from the pc and used a different phone line. The path is now not located near any other devices or power sources.
I connected mj to a different pc in the opposite corner of the room. I'm not positive but I believe this outlet is on a different AC phase and/or breaker. Doing this test makes me wonder about trying the laptop again, running off of AC instead of battery.
Using the laptop with AC did cause the hum to return. Unplugging it and running on battery make the hum disappear.
Now I am totally clueless with the hum and even more so, why it never existed with RCN voip or pots service.
