I think I already know this answer to this question (a trip to Sony service), but I wanted to see if anyone else has experienced this problem.

I used my VX-2000 as a locked down camera for a high school play. When I went to capture the tape, I found the the audio to be toast - very severe 60Hz hum. I did have the camera connected to AC, but not to anything else, i.e. no connection to the audio board. AGC was on.

This morning I easily reproduced the hum problem with the AC adpater connected, but I can also hear it (to a lesser extent) when running on battery. With audio level set to manual and the gain turned all the way up, the hum is very prevelent. I can control the amount of hum by merely moving my hands around the camera or moving the camera around the house. Connecting my XLR-PRO to the mic input makes the problem go away.

Clearly I have a ground problem of some kind that is allowing 60Hz to get picked up in the mic circuit.

Anyone else had this experience?

were you using the camera's built-in mic for the play? You mention the hum goes away when you connect an external line to the camera for audio. If that's the case, it sounds like the mic may have a problem and need to be serviced.