Tape problem or something a bit more sinister

[quatinus]

Queer problem:

Filming local church concert. Overhead mics attached to Canon XM2 via mixer unit and Canon XLR adapter. Camera controlled remotely via LANC.

I filmed a rehearsal to check levels etc. no problems - played back tape - happy with sound and picture quality.

I filmed the concert the day after using the same set up. Changed tapes at the interval. During recording the camcorder tv screen was displaying normal picture and sound levels.

Now here is the problem:-
When playing back tape one there is a period of 4 minutes or so of black screen - no sound. Then the a picture appears broken by a series of black bands together with sound distortion. After a while the picture and sound reverts to normal. I have now lost the first two acts.

When playing back tape two the same picture and sound distortion occurs for a period of around five minutes then reverts, again, to normal.

I was using re-used Sony Premium 60 mini DV tapes. One of which I used to tape the rehearsal.

I don't think the camera was affected by the mic connections or was being affected in any way by the mixer as I would assume that I would have noted that after I filmed the rehearsal and any interference would have been constant.

Has anyone come across this type of problem before? I need to get to the bottom of the problem as I film this type of event regularly and the last thing I want is a recurrence of the problem.

Help

[senu]

Strange.. could the problem be that the Lanc was firing off a pause, stop, play then record .. in error.( or an interfering wireless command)
This may be the Lanc controller or the camcorders recieving electronics

I totally admit It sounds far fetched but if you did that you would be reproducing the problem. as you describe it.. almost as if you were controlling the camcorder by remote control and then a kid with trigger happy fingers got hold of the remote!
I would think that the mic connections would result in loss of audio but not give you a blank segment of tape for video.
However you say these are reused tapes so it asssumes the recording was going on.. and no audio or video was being recorded..
It may be a camcorder fault which is manifesting as an intermitent failure to record audio and video for a short while. Some camcorders will not record any audio if the video is not being recorded

[quatinus]

My initial thoughts were that it may be the LANC sending out spurious messages but not convinced as these would have interrupted the record mode which would, I guess, have manifested itself on the monitor screen. I was watching the screen the whole time virtually and everything seemed normal.

Forgot to mention in my initial post that I tested the LANC and camera the following morning and the camera recorded perfectly well. Could be the start of an intermittent camera fault I guess but my gut reaction that it is more fundemental than that.

I had retensioned both tapes and I am wondering whether by doing so it may have caused the tapes not to travel over the recording heads properly during the first few minutes until the tapes had settled down to 'normality'. The variations of tension though would, I guess, have been so miniscule that I can't really get my head round that theory.

Brian