We recently tried to set up some CCTV cameras for our home and everything is fine except that the CCTV video feeds from some of the cameras suffer when we try to simultaneously connect the DVR and cable TV to a Samsung LCD TV monitor. It work's fine if you only connect them one at a time, but the moment you try them both (since we want a TV that's also a CCTV monitor) things just go bad. They're both on separate inputs though, with the DVR on the TV's VGA port and the cable TV connected through (what I think is) a UHF connector so I really don't see a reason for why this should be happening.
There's also only one other monitor which is connected only to the DVR through a different DVR output labelled 'Main Out" which uses a BNC connector to connect the DVR to the monitor (the other monitor with problems uses the VGA out). This one is also affected by the drop in quality when we try to connect the cable TV to the other monitor.
We've tried several things to try and fix this: We've tested this with different TVs (different brands and types), we've tried completely disconnecting the other monitor attached to the DVR, and we've tried switching out the power supply for the 5 cameras that are affected. All of it doesn't seem to make a difference.
Any help or advice would be appreciated. Thank you.