DS2 CCTV problem

[Engineer2012]

Hi,

I have a DM Digital sprite 2 installed on a job with 16 cameras, a lot of these camera pictures keep getting green screens but will dissapear for a while after the unit is reset. I have spoken to tech support and they have said it can be 2 things, first it could be the codec board which is on the way out OR it could be that one or more of the cameras is causing this problem as the V p-p is not at 1 volt.

Firstly has anyone experienced this before?

Second, how exactly do you test for 1v p-p output from the camera? And if you do test it and it falls out with this then is there anyway to change this or does it mean the camera should be bereplaced?

Thanks

 

[TheAlarmMan]

It's possible that it could be either issue but before sending the unit back or replacing it, you could try a few simple remedies.

The cheapest way is to disconnect the cameras and refit one by one until the problem occurs, then leave that one off and see is it still persists.

Or try fitting a new camera to the unit, just one and leave, again to see if the problems persists.

One way of testing the peak to peak value is to use a scope, you can also use a simple tester;
http://www.dipolnet.com/universal_cctv_tester_-_tomek-8_M2508.htm

There are many available.

Remember 1v peak to peak is a nominal value, it should not be over but can be as low as 0.3v and still have good pictures.

Normally you cannot alter the output voltage but some cameras do.

You can get signal boosters but your putting off the inevitable that the camera is on it's way out.

I'm assuming your using co-ax and not Cat5 and video baluns?

Does this happen only on the same channels?

 

[Engineer2012]

hi,

the problem doesn't happen straight away unfortunately it can take a few weeks each time before it reappears after restarting the dvr.

The system in question is part of a major retailer so l cannot have any downtime on the system.

The cameras are wired in coax rg59 and the problem presents its self in the form of when the 16 way multi screen is showing camera 1 screen goes green, then it moves to cam 2, then goes through all pictures one after the other and keeps doing this until reset.

I can send the unit for repair but i cant be sure this will rectify it if it is a camera fault and then i of course would need to organise a loan machine for that time period so i want to make sure the exact fault and not just guess but its proving difficult.

 

[TheAlarmMan]

If you think it's the cameras (which it could well be, overvoltage could be knocking the card out), you'll have to buy or acquire a peak level tester.
https://www.buyfromnorbain.com/Store/Product/0472590.aspx