Lines in monitor picture

[genestoy 0]

Hi,

My system has been working great since being installed 2 weeks ago. I have a question for the pros though. There are bars floating upwards on my screen (55" sony tv) in all 8 cameras. It is not noticeable during the daytime but at night when the infareds are on they are light almost white horizontal bars that rotate upwards slowly thru the picture then disappear and return at the bottom of the picture and keep on rolling. Not really a big deal but wondered what might be causing this?

thanks for any advice on this

Gene

[scorpion 0]

What you have are ground loops issues!

 

You have not described your situation so I will try to guess which one you may have.

 

Metal buildings such as warehouses, mechanic garages ect.

 

The cameras are bolted to the building, and then the wires are ran to another building. Because there are two grounding points one being at the camera, and the other being at the DVR or Multiplexor.

 

The solution is to isolate the camera from the building. You will have to be creative. You can use plywood that is painted to look like it belongs, or you can use plastic bolts, and nuts, and some kind of insulator between the mount, and the building such as plastic, or some kind of rubber.

 

_____________________________________________________________

 

Another ground loop situation:

 

Cameras at one building (of any material) that go through a DVR in one building then the wires go in to another building then connect to a multiplexor (or vice versa from camera to multi plex, then to another building then connected to a DVR).

 

The solution is to purchase ground loop isolators.

 

If the the second building is a small office style building off of a main building such as a night club with a detached small owners office, and there is a management office inside of the main building then you might try running a large ground wire to tie the two buildings in to one grounding point.

 

This is hard to due with most buildings, but there are some cases where you can get lucky.

 

It would depend on where the service point is (power, telephone, and tv cable). This is where the grounding point starts. A second building will have their own grounding point. The difference of potential between those two points is what creates the ground loop issue.

 

_____________________________________________________________

 

Third situation:

 

You may have a TV that has a bad power supply, or a leaky capacitor that is causing the ground loop issue.

 

This will do this when you are watching cameras, or when you are watching Sat TV, or Cable TV. The bars are always there!

[genestoy 0]

Thanks for the scenarios. It is a home system with a stucco exterior and wood framing all one single level building. Six cameras outside, 2 inside. Funny thing is the two inside cameras with infrared on do not have the fuzzy lines in them and they are the same identical cameras as the outside ones. I tried viewing them with the satellite receiver off and the surround system off and that did nothing. I have not tried viewing them with a different TV/monitor so possibly it is the big sony tv. But I would think if that is the case then the inside ones should act just like the outside ones? All the cameras go directly to the DVR via BNC connectors. They also are all powered by a 12v power panel which has individual lugs for each camera.

Thanks for any help

[scorpion 0]

http://focus.ti.com/lit/an/slla268/slla268.pdf

 

 

 

You have me stumped on this one.

 

It may be that the camera wires are running parallel with power wires causing an induction. That would be the only thing that I can think of.

 

Do the camera wires, and some lighting wire come through the same holes?

 

Are those wires running side by side??

 

You def have some AC leaking in to your system somewhere.

 

I would suspect the power supply, but the inside cameras are fine ruling out the power supply, unless you have multiple power sources?

[genestoy 0]

All the wires for the video and power come down from the attic in a wall with 120v power wires coming down the same wall but not in the same holes. New holes were drilled in the cross bracing (2x6) for each of the 8 wire sets but they are very close to the 120v wiring. If I installed bnc isolators which end would they go on? The camera end or the receiver end? Would the GB01 isolators work for this (they seem to be the least expensive).

Thanks again for your help.

[scorpion 0]

I would install them at the point where they work the best!

 

OK, try the receiver end first.

[genestoy 0]

OK, I think I will buy just one and play with it to see what happens, still can't figure why the interior ones are perfectly clear though. I just thought of something, the stucco here has chicken wire placed over the entire exterior of the house that the cement stucco is applied to, maybe that is what is doing it?

Thanks again

[genestoy 0]

OK, I went back and viewed the interior ones and they too have the bars but are barely noticeable because the infrareds are lighting up the areas so bright that they are hard to see. So it has to be the 120v leakage then.

[scorpion 0]

Perhaps if the camera mount is metal, and you have used metal screws.

 

I doubt that as you may have put plastic anchors in to the holes that you drilled.

[genestoy 0]

Almost every camera has two plastic anchors in the metal brackets and two metal screws thru the stucco and into studs which more than likely could have hit the chicken wire going thru.

[scorpion 0]

Being stucco the chicken wire does not go in to the ground.

 

Here in Florida the stucco stops at a point above ground level. Is this the same for you?

 

It may be that the lathe has come it to a ground point such as being wrapped over a conduit pipe.

 

The problem here is that the chicken wire is at the same ground potential as the rest of your CCTV system.

 

I am now declaring the power supply the problem.

 

Disconnect every camera, but one. Using one of the outside cameras see if you have the bars still.

 

The power supply is leaking AC. It may be that all of the cameras may be taxing the power supply. I say that, but I do not know the type, or the quality of your power supply.

 

Do you have a regulated 12 volt wall wart transformer that can feed one outdoor camera?

 

This will trouble shoot your power supply real quick!

[genestoy 0]

You nailed it! I got out my digital voltage meter and the output with all 8 cameras running with their leds on measured 10.8 volts at the terminals (and I am sure much less at the ends of some of the 100' runs). I disconnected 2 cameras and it went to 11.4, disconnected 2 more and the voltage went to 12v. With the 4 cams disconnected the rolling bars virtually went away, so looks like the power supply can not handle these cameras. So I can either buy another power supply and run just 4 cams or get a better one that will run all 8?

[scorpion 0]

You nailed it! I got out my digital voltage meter and the output with all 8 cameras running with their leds on measured 10.8 volts at the terminals (and I am sure much less at the ends of some of the 100' runs). I disconnected 2 cameras and it went to 11.4, disconnected 2 more and the voltage went to 12v. With the 4 cams disconnected the rolling bars virtually went away, so looks like the power supply can not handle these cameras. So I can either buy another power supply and run just 4 cams or get a better one that will run all 8?

 

 

That is an one that I cannot answer. I would say buy a power supply that can handle the cameras that you have. What would that cost?

 

Would it be cheaper having two inexpensive power supplys verses one higher amperage one?

 

While you are at it you could move to a higher channel power supply so that you have more amperage, and you can add on more cameras down the road.

 

I am glad to hear that the mystery is solved before you went and stripped off all of your stucco, and lathe on your house!!! LOL!

[genestoy 0]

Thanks for all your help. I have a solid state power supply that I am going to connect to the power panel in place of the large "coil" supply that is currently in the power panel which the coil one is rated at 12v 5 amps and the solid state one is 150w at 12.5 amps to see what happens.

Again, thanks for all your help with this.

[genestoy 0]

Scorpion,

I just wanted to say thanks again for your help. Today I built a new power panel using the 150 watt 12.5 amp solid state power supply that I had, fused each camera with a 1 1/2 amp fuse, used power strips for the connections and now the pictures are way better and NO more lines/bars. My power supply is adjustable from 10v to 15v and I set it at 13.2 volts as some of my power runs are 100 feet to the cameras so I figured they should be getting about 12v now or a tad less at the camera itself. I know one thing that the infrareds are brighter now also. I checked all the voltages tonight with all the infrareds on and it maintains the 13.2 steady on each lug instead of the 10.8 the old power supply was doing. Problem seems to be solved!