Back in 2011 I bought a Unimo DVR with a number of CVBS KCE brand cameras with inbuilt IR (from a forum member actually). Over the last year or so some of the cameras have failed and have been replaced with later models of the same cameras. Those replacement cameras have worked well, both night and day operation, and no adjustments made in the OSD menu.

Of late CVBS cameras seem to be getting a tad difficult to get hold of, and recently I bought 2 x dome cameras Altronics part # S9121E and 2 x bullet cameras part # S9134E, two to put in service and the others as spares. They seem to be quite good quality cameras, and I have set them to CVBS mode.

However I'm having trouble with their night operation, in that after dark they are cycling from colour to BW every few seconds. Via the OSD I pushed their D-N (DELAY) & N-D (DELAY) figures out to 60 seconds to at least alleviate the thrashing somewhat while I figure out the solution.

Their default DAY/NIGHT setting was "EXT" so I changed that to AUTO. I have since fiddled around with the D-N (AGC) & N-D (AGC) figures without success stopping this switching from colour to BW problem.

I have tried low, mid-range and high AGC figures for both D-N and N-D with no effect on the problem. I did read somewhere that the N-D setting must be higher than the D-N setting (why I don't know), but in any case that hasn't been successful.

The IR LEDs are on all the time at night, so it does not appear to be a lack of IR light that is causing the issue. I have checked the PSUs including swapping them with new and the problem remains with the cameras. The spare cameras exhibit the same issue, so I am convinced it is a setting problem. At night in the BW mode the video is outstanding, but in colour mode little is discernible. See pix

There are no external light sources that could be triggering the issue, and the original KCE branded units worked out of the box fine in the locations.

The main settings are in the attached document.

Advice would be appreciated





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