I finished wiring 4 stations around my music room to my mixer, and tested everything and I have continuity through all the cables to the mixer. I tested the guitar jacks, and everything is sounding great. When I tested the mic connections, two of them are great, they are both on the same wall that is an inside wall.
However the other two XLR's are behind the baseboard on an outside wall. There are electrical outlets on that wall, they are about 12 inches above the baseboard. One of these two XLRs is presenting a buzzing sound in the cable.
I have checked continuity with a meter, and I have no cross connects, I used a cable tester, and all the lights are fine, so the cable appears to be connected properly. If I plug in a microphone at the workstation, and look at the board everything appears fine, except the level light for the gain is slightly lit. If I remove the microphone I get a loud buzzing in the speakers, the gain light stays slightly lit, and if I reattach the mic, the buzzing disappears.
If I press the PFL button to see how strong the signal is, I am getting a very high signal in that cable with out a microphone attached, and if I reconnect the microphone, the buzzing goes to the background. And the microphone work pretty good.
None of the other XLR channels/cables are doing this.
I have pics but could not find the place to add them. They show the entire mixer, all the setting are the same on each channel, then the next two pics show the PFL activated, and the steady on level light, and the huge noise that is induced by the cable to the mixer... any idea what this might be?