I have a Lorex model LH185 8 camera security system. I have the wires run for 7 cameras, 5 display fine on the monitor until I plug in either of the last 2, then the others loose signal. Any suggestions?

Have you tried contacting the manufacturer or the installer for assistance? Of course this is assuming that you didn't set them up yourself.

How do they connect to the DVR? The best I could tell from looking up a little bit online was that the unit has 4 BNC connections, but I didn't see anything specifically about how the cameras connect.