wick1144

I know that DC power is on coax, but at very low voltage. Millivolts, not 30+ volts.

I don't know how the voltage got on the coax. Once I placed all power in the same circuit, the voltage was eliminated. I guess a grounding issue in the building between the 5th floor and floors 1-4. Meter works fine.

To make a long story short, I eliminated the voltage on the coax shield by running power from the head end to the cameras putting everything on the same circuit. The non-working cameras had to be replaced. Just wondering if the AC voltage on the coax shield had anything to do with the camera failure. Thanks for your input, but turning the page on this.

No. It's not the display settings. Not quite that basic. Wish it was. Thanks for the thought.

ok Maybe I didn't explained the issue incorrectly. The display is showing 16 camera windows. I am only getting video on 4.

I have had ground loop issues that we're not on the last camera. On the newer DVRs, at least this brand TVI compatible DVR, the ground loops can completely eliminate the picture. Much more sensitive.

Which dvr do you have ? Truvision TVR15HD What type of cable RG59 What length of cable Varies 30-100' What power to each camera 12vdc plug in transformer.

The only thing I can think of is the difference in grounding effectiveness between the ground at the DVR location and the ground at the camera location. This difference in grounding effectiveness would result in voltage. That's my guess. That's why I'm looking for help. I've been doing this for over 20 years and never saw this before. But I never really looked.

Powered locally at camera, not at DVR location. 12vdc transformer

Yes I moved cameras to different ports. All cameras with the voltage issues did not work on any port. Cameras without voltage issues worked on all ports

All of the cameras were working before I switched the DVR. I didn't move or change anything other than the DVR. I was checking for ground loops and any voltage issues that could affect the video and found the voltage. I figured that the newer HD capable DVRs may be more sensitive to electrical issues.

I replaced an old DVR with a new HD TVI DVR. All cameras worked on the old DVR. After connecting to the new DVR, four of the 16 cameras worked. The remaining cameras did not. I did some troubleshooting and found that there is 32-33 volts AC on the meter when I test between Coax shield and DVR (testing at the BNC camera input ground). I also tested between coax shield and ground on outlet (third prong) and got the same. I've never seen this before. The four cameras that work, do not have this voltage. I've heard of ground loop issues, but this is a lot of voltage. This is a five story building and cameras are powered at outlets at the camera site, not at the DVR site. I don't know if a ground loop isolator would work on that much voltage. Besides running new power cables from cameras to head end, are there any suggestions.?