Pro Focus LLC | 05/27/16 10:33pm
Sounds like a ground loop. Is it a metal building?
Or it could also be a lighting issue. Is it in an area that has fluorescent lighting?
What type of wire are you using? Is it pure copper or CCA/CCS? Baluns?
Sounds like a ground loop. Are all the cameras on the same outlet as the recorder?
You can get a ground loop isolator, this one says its for HD, but ive never used it.
Agreed with the above. It likely is a ground loop. When your cameras are powered from a different 120vac circuit than your recording device, there can be a slight difference in the voltage. Not much, .5 to 2 volts (sometimes more). That is a difference in potential. That one or two volts will travel up the ground wire of the video camera to the recording device and cause the roll (black bars or lines that roll up the screen) you describe. The greater the difference in potential, the heavier the black bars will look on your screen.
The cleanest way to eliminate it is the ground loop isolator U1 mentions.
You can check by installing a cheater plug (2 prong to three prong adapter on the camera power supply and recorder (you are "floating" the system), removing ground for a test. If the bars go away, you have found your problem. The plugs cost about dollar each. If they don't, you may have to look for other sources - lighting etc.