by Lawnboy » Tue Jan 01, 2013 11:55 am
I am having an interesting problem with a broken video mixer that I bought myself for Christmas this year. Maybe someone here can offer me some clues as to what is wrong. So here is the story: I bought a Panasonic WJ-AVE5 (NTSC) digital video mixer with internal frame synchronizers on Ebay. The listing said that it was producing distorted video, and after some diagnostics I found that the sync trigger on the NTSC decoders are firing during the line. After talking with a friend with some equipment I got my hands on a proc amp, and by extending the sync on the video input signal I can get a stable picture. The output signal from the mixer is clean. All three of the inputs have the same problem, and the unit still had its warranty sticker intact, so no one had opened the case prior to me.
Here is what I am confused about:
Why is it set up this way? I have tried multiple video sources including a Panasonic camera with no luck. It seems to be a consumer-oriented device (i.e. RCA connectors, not BNC, no impedance switches on the back.) So I would assume it should accept a regular composite / S video signal. I can’t think of any special circumstances in a production chain that would require a different sync level set up, and I assume someone would have had it fixed if it was like this when new.
How can I fix it?
I have the service manual for the mixer, and out of all the adjustments that could be made to the analog signal section there was nothing to adjust the sync slice. I don’t know if anything else is out of adjustment (Y gain, etc) that would cause this behavior since I don’t have a true waveform monitor, only an ordinary oscilloscope.
That should be enough info. Any thoughts?