Camera suddenly goes to video loss

[finalsight 0]

Hi

i have taken over the maintenance contract and i am having a problem with one of the cameras. i unplug the camera and plug it back in and the picture comes up, but after some time it goes to video loss. i have changed the channel on the dvr, i have changed the camera, i have changed the power supply, it still always ends up going to video loss.

could the cable be damaged some how where it would only transmit a signal for a certain period of time??????

please help.

[scorpion 0]

What kind of camera is it? What voltage is the camera?

 

Did you measure the voltage at the camera with it powered on?

 

What was the voltage?

[finalsight 0]

if my memory serves me correctly it was a security evidence 1/3" ccd d/n camera. i then changed it to a simple ir bullet camera.

i did measure the voltage bot with the camera on and off.

the voltage was 12.62 i think.

both cameras are 12vdc

[scorpion 0]

Is there somekind of bnc to rca adapter involved where the wire hooks up to the camera?

 

If yes replace that adapter.

 

If no, then OH boy! You got problems.

 

If you have a battery powered monitor, then you could test it at the camera to see if the video stays up, and then you may have to replace that coax. Is is copper shielded coax, or aluminum shielded coax?

[RickA 0]

What about the amp requirements for the camera, and what is the amp that are supplied by the transformer?

[ispy4u2 0]

How far is the cable run to the camera?

 

Are you using coax or the plug and play type cable?

 

Do you have a cable tester? Check to see if you have a ground loop issue.

[finalsight 0]

the cable run is about 80 m

we are running rg59 with an aluminium sheath.

we un fortunatrly do not have a cable tester to test the ground loop.

the more i am hearing the more i am convinced it is a cable problem, i have read some where that if the sheath has a nickk in it it can some times act as a capacitor and the picture will disappear after some time of it being up

[scorpion 0]

we are running rg59 with an aluminium sheath.

 

Problem solved!

 

You are using aluminum braid. You need to have copper braid. You may need to check the center conductor as well. It may be a steel center with a copper coating on it. The CCTV signals are low freqs, and they travel in the center of the center conductor. Cable / Sat are high freqs, and they travel around the outside of the center conductor, and this is why they can get away with copper clad center conductor. 80M is too far for the type of coax you are running.

 

You are def losing signal!

[finalsight 0]

thanks for that

i have one question though, we never put that cable in the previous installer did, the owner informs me that he has always had a picture (for the last 3 years), it is only recently that it dropped. our companies standard is copper and i will replace the cable with copper.

thanks

[scorpion 0]

3 years?

 

With CATV that would not effect that style of a signal. The fact that it worked to begin with is a miracle! With 3 years it may have come to a point where it can push the signal through. I would have thought that by cutting the coax back by about a foot on the camera side would resolve your issue if you have the length to spare.

 

The reason being that the elements have worked their way in to the coax, and you have corrosion that you cannot see with the naked eye. Cutting it back a foot may get you passed that corrosion, and it may work again for a while. If this works then you can preplan the new cable run rather then "being" caught off guard. What would be nice is if you can do other unrelated work in the future, and you can tie the replacement in at the same time so that you can kill two birds with one stone, and make some money while you are at it.

[finalsight 0]

ok that does make alot of sense to me. we are actually going out to site on monday to do two new cable runs and i think i will just put a new cable in with copper sheath and center.

thanks so much for your help