[Bill Farnsworth]

The audio hum has been bugging me for quite some time when the camera is connected to a monitor via component or composite or S-video. ALL methods of isolation that any professional camera crew were in vain. This included ground lifter, battery power on camera, monitor, mixer. Isolating HMI ballasts. Removing dimmers and installing a ferrite choke on the D4 component out cable. A few things were discovered. A composite SD signal via coax was the quitest. Setting the component output to 1080i produced the worse hum. Two headphones via Y cable reduced the hum. However, nothing eliminated the buzz or hum. We finally just gave up and would disconnect the monitor (Panasonic 17″ field monitor) when it came time to roll.
I then discovered quite by accident, that (in the recording menu)setting the audio to -60db instead of the default -50db, the hum was eliminated or was so far down in the basement that it was virtually unnoticeable.
I have no idea why this works. I don’t even care at this point. I just know that it got the job done.

Regards,
Bill Farnsworth.

[Bill Farnsworth]

I am not Jack, but I did have this problem come up twice in the past.
The second was resolved by replacing the battery in the microphone. Hearing aid batteries can die in a matter of minutes.
The first was the worse of the two. The phantom power switch was not fully seated into the off position.
The audio was fine thru the headphones but on playback there was more static hiss and hum than the desired audio which was way in the background and off mic. This told me that the primary mic was not recording at all and the camera mic was bleeding over.
So. Replace the batteries early and often. Verify that the phantom power switches are fully seated in the off position when not in use. (I have taped them over just keep from accidently hitting them)
Regards,
Bill Farnsworth