fas 0 Posted March 6, 2009 I took over a job which has video and power run on cat 5 with baluns. No baluns were used for power and they did not double up. Some runs exceed 150-200 feet. They were powered by 12 volt 300ma plug-in power supplies. I installed a 16 channel 12v 25amp power supply for the new cameras I am going to install. I installed one and it works great. They asked me to connect the old cameras to the new power supply. I tried a few and the video was horrible! Lines, jumping, you name it. I reconnected the old cams to the plug-in power supplies and now they work fine again. Why would this happen? I used 18/2 power for my new cameras and they are fine, but the cat 5 caused horrible video. Share this post Link to post Share on other sites
scorpion 0 Posted March 6, 2009 Is the power supply located at the same point where the wall transformers are located, or are the transformers located with the cameras in another building? The reason I ask is that you may have ground loop issues between the two power points. If you wanted to use your power supply then perhaps the cameras need to be isolated from what they are mounted too? I have seen this with commercial metal buildings when the cameras are bolted to the iron work, or the the metal outer walls. If you had to isolate them then look for nylon bolt, and nuts, and you can go to a hobby store and ask where they keep their styrenne plastic sheets. You can put the mount on the plastic, and cut out the shape to provide insullation. If you want to test the theory then just use cardboard to isolate the camera. What do you think? Share this post Link to post Share on other sites
DaveM 0 Posted March 6, 2009 Ground or voltage level issues sure could be a problem here. Check your voltage at the camera while it is powered on to make sure you don't have to much voltage drop in the cables. Use two pair for power if not already doing so. Try using the little power supply to supply power from the DVR end. If that clears it up then it probably is a ground loop. If you are using one of the rj-45 to video converters you will need to make sure that the adapter is not grounding the power jack through the BNC connector. If the power is being connected right to the wires then that shouldn't be a problem with this test. It never hurts to make sure that you have a good ground at the DVR, you can never tell how good the one at the power cord is. Run a #14 or larger wire from a screw on the DVR case and from the power supply case to a good ground. A good ground is building steel, cold water pipe, or a ground rod. If you are in a computer or equipment room there may already be a ground bus you can connect to. If it does look like a ground loop, you may be stuck isolating it like Scorpion says-that is not a good idea though if it is outside. You could also try running a good ground to the camera as well to try and bring the two ends ground potentials closer together. I am not in the CCTV business and this advise comes from my own experiences. Share this post Link to post Share on other sites
fas 0 Posted March 10, 2009 Well, the problem was a polarity issue! The guy that wired before me didn't have a uniform way of wiring and wired some backwards! My question now is why did the power supply not trip the breaker? Other power boxes I have used tripped the breaker when the polarity was reversed. Is this not a feature on all power supply boxes? Also, how much damage can be done to a camera by reversing the polarity? Share this post Link to post Share on other sites
Rebco 0 Posted April 9, 2009 Depends on the camera, have you ever tryed fried camera? Share this post Link to post Share on other sites
