hcesurveillance 0 Posted June 6, 2009 Hi, I have x6 IR outdoor bullet cameras - x1 PTZ - a DVR 9 ch - and a 9ch power supply box. Everything is new! All of the cameras has the same problem! When they capture a moving object, that moving objects flickers (looks wavy). I have test one of the cameras with a shorter cable direct to the tv with another power supply it looks perfect. Then i put one of the camera that are already installed direct to the tv (no dvr) and using the power supply box of the system is much better on moving objects but with horizontal lines. (that is with the camera directly to the tv) those horizontal lines go away when i just touch the bnc inputs of the dvr with another bnc terminal from another camera that is installed to the same power supply. Cameras are installed in brick wall! Please help is a new system! Share this post Link to post Share on other sites
Soundy 1 Posted June 6, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. Share this post Link to post Share on other sites
hcesurveillance 0 Posted June 6, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. What can i do to solve that problem? Very helpful thanks a lot! Share this post Link to post Share on other sites
Soundy 1 Posted June 6, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. What can i do to solve that problem? Very helpful thanks a lot! See bolded text above... Share this post Link to post Share on other sites
hcesurveillance 0 Posted June 8, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. What can i do to solve that problem? Very helpful thanks a lot! See bolded text above... They do work perfect individualy! What can i do to solve that problem? Share this post Link to post Share on other sites
Soundy 1 Posted June 9, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. What can i do to solve that problem? Very helpful thanks a lot! See bolded text above... They do work perfect individualy! What can i do to solve that problem? Just keep it that way... that's the only thing I've found that fixes it 100%. Again, remove the central power can, mount a power bar or two as needed, and just be done with it. I've fiddled with filters (chokes and caps), assorted different grounding strategies (PSU to DVR case, video input shields to case, shields to PSU, any or all of the above to earth ground, and completely lifting all grounds), all to no avail. Different tweaks improve some cameras and not others, but the only thing that clears up ALL of them is having a separate transformer for each one. The only other 100% solution, as noted previously, is to replace them all with 24VAC cameras and a 24VAC power supply. Share this post Link to post Share on other sites
hcesurveillance 0 Posted June 9, 2009 Are these all (at least the IRs) 12VDC-powered cameras? If so, you may have a ground-loop issue. Try powering each camera off its own individual transformer (wall-wart style), or at least test it on 3-4 of the cameras simultaneously, and see if that clears up the probelm. What can i do to solve that problem? Very helpful thanks a lot! See bolded text above... They do work perfect individualy! What can i do to solve that problem? Just keep it that way... that's the only thing I've found that fixes it 100%. Again, remove the central power can, mount a power bar or two as needed, and just be done with it. I've fiddled with filters (chokes and caps), assorted different grounding strategies (PSU to DVR case, video input shields to case, shields to PSU, any or all of the above to earth ground, and completely lifting all grounds), all to no avail. Different tweaks improve some cameras and not others, but the only thing that clears up ALL of them is having a separate transformer for each one. The only other 100% solution, as noted previously, is to replace them all with 24VAC cameras and a 24VAC power supply. How can i check the coaxial for those ground! With a multimeter? Thanks it has been great! Share this post Link to post Share on other sites
Soundy 1 Posted June 10, 2009 You can't. You MIGHT be able to see the problem with an oscilloscope, but that won't fix it. Here's the problem: with baluns, your signal is running through a pair of coils on either end. That effectively makes for a very, very long piece of wire. The signal ground is shared with the power ground at the camera, and the power ground then makes for a relatively short ground path. Between the two, you now have to separate paths to ground for each camera, one relatively short, one extremely long. When you tie all the cameras to the same power supply, you're giving all of them a common ground point over the short run. They also have a common ground at the DVR, with the long runs. This makes for a large number of mis-matched ground paths, which leads to all manner of induced noise in all the cameras. So again, the solution is simple: remove central power supply, replace with power bar, and use an individual transformer for each camera. That way, they all have a power ground that's isolated from the other cameras. Share this post Link to post Share on other sites
