kumaiti

Hi all. My first post here in the forum. I need a little help trying to figure out what is the problem with a color CCTV camera here where I work. (I am responsible for them even though I am just the IT manager, not a CCTV-engineer of some kind...) The camera is a Vista 1/3" color camera installed in a dome mount. It is installed in the ceiling of building's entrance and is supposed just to show general images of the area (no faces needed). It is connected to the DVR by CAT5 cables. It has a dedicated power supply. Now, what is the problem? Every once in a while, the image gets dark. It doesn't happen all of a sudden, its a gradual change that takes about 20~30 minutes. When it gets dark, you can barely see anything on it. Then, after a few hours (or a few days in one case), the image gradually goes back to normal. In the attached pics Image01 and Image02 you can see how it looks during the day and during the night. In the third pic (image03), it is how it looks when the problem arises. WHEN does it happen? It seems to happen only when there are events going on (it is the entrance of an exhibition hall) and it usually starts in the morning when they start moving equipment in for the event. It usually doesn't stop when the event is over and once it stoped during the event itself. Also, once it started during the event. I suspect it is a power issue but I can't be sure because of the apparent randomness of the problem. Thanks for any help.

Cheap ones. I honestly don't know the brand name. What could cause this kind of thing? Just general malfunctioning of the video balun or something more specific like "being too close to a power supply cable" or something like that?