Help to ID DVR - Image problem in all cameras

[PonchoN 0]

This system was working OK for at least 1 year and 3 months. 12 cameras most of them with IR.

Now all the images are in black and white with green or black lines below the image.

 

I can get some examples if you need

 

Each camera have an independent power supply, with passive balun.

We made the next tests with no results.

 

1. We Connect a new camera with balun and then rg59 at least in 5 ports of the DVR, independent power supply, we have the same images

 

2. Unplugged the DVR and uninstalled from the rack and plugged into a different power source, tested with the new camera (alone), same result.

 

3. The voltaje receive in the DVR is OK.

 

Well, what you think?, I think is something with the DVR.

 

thanks in advance

[Squiffy 0]

Sounds like the DVR to me. Possibly a crystal reference oscillator has drifted off frequency. Is it used in a well ventilated area?

[PonchoN 0]

Thanks for your answer. No so ventilated maybe reach temperatures above 27 C / 80 F. The DVR is an Avtech AVC787. It´s possible to change this crystal?.

 

Thanks!

[tomcctv 187]

on all 12 cameras....... try changing your monitor before taking your dvr apart. not had much to do with this type of dvr can you switch between pal and ntsc on the dvr

[PonchoN 0]

Yes, 12 cameras all the ports. I saw this problem thru Internet and into the LAN.

[Squiffy 0]

You'd need to know which crystal - there are a few inside the AVC787. It's also unclear if that's the actual problem. I suggest removing the top lid and seeing if the problem still exists, or occurs only after it's been switched on for a while. If the problem is indeed a reference oscillator that's slightly off frequency, the crystal itself may not be the problem, but the components around it may've changed value slightly (they tune it to an exact frequency).

[PonchoN 0]

Ok, I´ll do the test you suggest. If the same, maybe a Hardware Reset