No video on one cam out of an 8 cam install

[DKtucson 0]

Hey folks,

Here's the situation--did an 8 cam install. The client was adamant about it going into conduit to make it more vandal proof. I have one fairly short run of cable--about 50ft max--where I get a pretty blue screen.

Factors:

RG59 siamese cables with 7 of the 8 cables bottlenecking into a 1" conduit going into the house.

Power checks ok at 12vdc.

Using twist on bnc connectors.

It worked for a bit until I went to finish off mounting the junction box cover--which makes me think bad connector/cable.

I've used the same connector ends on a similar length of cable NOT going through the conduit tightness and the cam works fine.

 

I did an initial continuity check by stripping the far end and joining the center core to the mesh , then went to the inside termination and put my test leads black to the mesh and red to the center core wire--it showed continuity. But my thought is that if they are mashed together elsewhere it will show the same result and be grounded out.

 

So..for a more valid test my thought would be to hook up 12vdc to the video cable and see if 12v is being passed through to the far side----any other pointers or things I'm missing?

[tomcctv 190]

Hey folks,

Here's the situation--did an 8 cam install. The client was adamant about it going into conduit to make it more vandal proof. I have one fairly short run of cable--about 50ft max--where I get a pretty blue screen.

Factors:

RG59 siamese cables with 7 of the 8 cables bottlenecking into a 1" conduit going into the house.

Power checks ok at 12vdc.

Using twist on bnc connectors.

It worked for a bit until I went to finish off mounting the junction box cover--which makes me think bad connector/cable.

I've used the same connector ends on a similar length of cable NOT going through the conduit tightness and the cam works fine.

 

I did an initial continuity check by stripping the far end and joining the center core to the mesh , then went to the inside termination and put my test leads black to the mesh and red to the center core wire--it showed continuity. But my thought is that if they are mashed together elsewhere it will show the same result and be grounded out.

 

So..for a more valid test my thought would be to hook up 12vdc to the video cable and see if 12v is being passed through to the far side----any other pointers or things I'm missing?

 

Hi DK. undo your center core and mesh and test again. this will also show if you have a short.

[scorpion 0]

I second the above advice.

 

I have a question: Do you have video at the camera with a monitor?

 

I would cut the end off of each end of the cable, and reconnect the connectors, and see if that clears the problem.

[DKtucson 0]

thanks for the replies..I'll be back at the site on thursday. The camera works ok hooked up to a different line and a camera that is working at another spot does not work when hooked up to that cable.

IT DID WORK MOMENTARILY--until I went to fully mount the cam plate cover to the gang box --jiggling the wires caused it to go out. I have redone the ends numerous times and am doing it the same as the other 7 cams that are working fine. I'm also swapping out connector ends and those same ends work on another cam.

I've taken that camera down completely and wired it up on a desk and jiggled the wires--it stays on so it's not the cam pigtails.

I have misgivings about conduits that are tight.. the nature of having to pull the cable stresses the cable. I've also ordered up some better crimp connectors

[Soundy 1]

It would take a *LOT* of force to actually crush the wire to the point it shorts between the core and the shield. You could drive over most coax with a truck and while it's not very good for the cable, it wouldn't cause a short, and likely wouldn't cause a break either. At worst, crushing it like that would affect impedence, which could affect loading and noise rejection. For a short, you'd need some sort of physical damage by an outside object.

 

If you can, get ahold of a 75-ohm terminator, they make handy diagnostic tools: put one on one end of the line, then measure resistance across the tip and shield at the other end. A single reading will tell you if there's a short or open.