medievil2003 0 Posted July 29, 2009 Hello Everyone, Please do bear with me as i have not installed a large system like this before. I have 20 dome camera's on all floors of the hotel, all cables are run down to the basement comms room. At first, i made the mistake by connecting the power via terminal blocks & then realised a better option would be to crimp the wires with the "Krimps". Apart from that, around 18 of the camera's are working, all hooked up to the DVR and network. In the comms room i am using seperate power supplies which the power is cherryed off from each supply (max of 5) On one of the cameras, in this case (fire exit) if i disconnect this from the power another 3 camera's will turn off. I just can't work out why, is it because they are feeding from that power? My other problem is the white fuzzy lines & ghosing, not seen so much on the main monitor but more on the computer screen (networked), but the lines are still on the monitor. There are a few floors that are still left to crimp, so im just guessing at the moment the problem is the power on the cameras that have not been crimped yet? Any help would be fantastic. Thank You Share this post Link to post Share on other sites
Soundy 1 Posted July 30, 2009 On one of the cameras, in this case (fire exit) if i disconnect this from the power another 3 camera's will turn off. I just can't work out why, is it because they are feeding from that power? My other problem is the white fuzzy lines & ghosing, not seen so much on the main monitor but more on the computer screen (networked), but the lines are still on the monitor. There are a few floors that are still left to crimp, so im just guessing at the moment the problem is the power on the cameras that have not been crimped yet? I suspect these are related. Are these cameras all powered by 12VDC? If so, it's likely that the "other 3" cameras are getting their power ground through the one camera's coax, since move 12VDC cameras use a shared ground between power and video. In other words, the three cameras may have a "+12V" connection but not a solid ground connection, so the power is grounding via their coax runs, to the DVR, and back to the power ground on the fire-exit camera, through its coax run. Disconnect that camera, and all of them lose their ground. This kind of situation also leads to ground loops and similar such issues, which can lead to the ghosting problem you're seeing. Share this post Link to post Share on other sites
medievil2003 0 Posted July 30, 2009 Hi, thanks for your reply. Today i purchased an 18ch power unit, not just for the problem i was having but organisation. I did think this would help the situation, but the problem is still the same. If there is a grounding problem via the coax, would you advice i take the dome camera's down and check them individually to make sure no wires are touching anything they shouldnt be? The wires run are siamese, and the coaxial is shielded. Would this kind of problem occur if the shield around the coax gets slightly attached to the coax it's self? If this is not the case, could you suggest anything and everything i could try? The client at the moment is not aware! so i have a good week on my hands. Thank You for your reply. Share this post Link to post Share on other sites
Soundy 1 Posted July 30, 2009 ALL coax is shielded; that's the definition of "coaxial" - two conductors on one axis. If the shield and center conductor were shorted, you'd have no signal at all. Assuming all power and video connections are solid, I'm at a loss. Then again, I've been working long days in the heat, so my brain isn't running at full capacity right now Share this post Link to post Share on other sites
medievil2003 0 Posted July 30, 2009 Ok, Im sure ill get there eventually. I always accept a challenge in business! When your brain has cooled down, maybe after a beer? lol it would be great to try a few things you suggest. Thanks Again. Share this post Link to post Share on other sites
mitstarion 0 Posted August 3, 2009 Try isolating the problem by connecting individual power supplies "wall warts" instead of the 18ch power supply. This way you eliminate group loop and know the faulty cable. Share this post Link to post Share on other sites
tomcctv 189 Posted August 10, 2009 hi. are you using crimp on bnc or are you using the screw on type. also please remember on your cable you need to cut 10mm of the sheld back. Share this post Link to post Share on other sites
