Color image became b&w with blauns on my PC DVR. why?

[vmb 0]

Hello.

I have a very strange problem to solve.

I mount a video system of 10 color cameras(350 TV Lines; 220 V) located at distance between 45 feet and 600 feet from DVR.

I used passive blauns(NVPT-111VTS ) and Cat5 FTP Cable for cameras in range between 45 and 150 feet and active blauns(NVPT-A111VT) between 150 - 600 feet.

To test video cameras and cables i used a analogic monitor. All of them provide a perfect color image on the monitor during the instalation process.

After that, i brought the DVR (PC BASED - 2 PCI Card x 8 video input at 200fps/card - 25fps/camera) and i was very surprised when i sow the image black and white and not stable FOR ALL OF THE CAMERAS(including the near one). DVR was working fine with coax cable between 45-150 feet without blauns.(it was tested before in other site)

 

After a while of trying and testing , i brought a non PC DVR (Stand alone 4 input) and i tried 4 of my far distance cameras and the image was perfect just like on the monitor.

 

Somebody told me on the phone to put a 75 Ohm resistance between + and - on the wire at DVR side.

 

What do you thing? cand you help me please? sorry for my english!

thank you for your time.

[Kiwi 0]

yeah, it sounds like the video inputs at the card are not terminated correctly. It there a jumper, switch or software setting on the card regarding loopthrough? Should be on 75 or "off."

 

If not, return the card for one that works.

[vmb 0]

I tried with 75Ohm resistance. The image is darker but is still black and white and not very clear.

I don't know that elese to do.

[survtech 0]

You should not put the 75 ohm resistor across the pair of the twisted pair; it should be after the balun. Twisted-pair is 100 ohms and a 75 ohm termination will cause problems. In theory, the best place for termination is at the board's input itself. If that is not possible, use a "T" at the BNC or RCA input and place a terminator there.

 

By the way, is the capture card set for the correct format (NTSC or PAL)? If you set it to the wrong format for the cameras you are using, the picture would come out in black and white.

[vmb 0]

First thank you for your time. I try to put 75ohm resistor on the twisted pair before and after the blaun and i also try to stik it to the board in the computer. In all cases i have the same result - not working fine (b&w).

I also check my DVR for NTSC and PAL. Now is PAL but i try NTSC with no result.

 

I don't understand what is wrong with the PC DVR? With non PC DVR image is perfect and color.

 

My camera is AVC565

[cctv_down_under 0]

A pc based DVr is 1.1v peak to peak and analogue or even some standalones for display only require 1v peak to peak, try testing your camera and baluns on a very short fly lead....IE move the dvr to the cam and run a small lead...be carefull with termination of baluns, becasue how you terminate the twists really matters...IE did you unravel too much twist, this results in loss of colour burst.

 

Step 1 - test camera into analogue service monitor..if you get colour then

Step 2 - Test with a short run and your baluns...if you get colour

Step 3 - Test with the long run and baluns...but power the camera locally...loss of voltage can drop a signal to below the peak threshold for colour..colour is the first thing you will lose...if you dont get colour

Step 4 - Ensure you are getting enough power to the camera..remember you are running on thinner wires...so more ability to loose voltage..

 

If you get colour on local power or shorter runs, then you know its either termination or cabling or baluns.

[msnancy 0]

First thank you for your time. I try to put 75ohm resistor on the twisted pair before and after the blaun and i also try to stik it to the board in the computer. In all cases i have the same result - not working fine (b&w).

I also check my DVR for NTSC and PAL. Now is PAL but i try NTSC with no result.

 

I don't understand what is wrong with the PC DVR? With non PC DVR image is perfect and color.

 

My camera is AVC565

 

I wonder what's the standalone DVR format when you use and get a perfect image ? if it is in NTSC then your PC DVR without NTSC format will be the source of the problem.

[vmb 0]

Step 1 - test camera into analogue service monitor..if you get colour then

Step 2 - Test with a short run and your baluns...if you get colour

Step 3 - Test with the long run and baluns...but power the camera locally...loss of voltage can drop a signal to below the peak threshold for colour..colour is the first thing you will lose...if you dont get colour

Step 4 - Ensure you are getting enough power to the camera..remember you are running on thinner wires...so more ability to loose voltage..

 

First i test one camera with passive blauns and 1 meter cable. The image is black & white. I test the same camera on 30 meters coaxial cable and i sow a perfect color image.

All the camera are power at 220V with source cables between 20-30 meters.

I also ask my supplyer and he answer me he heard about the problem and the main reason is the FTP cat5 cable. He told me i have to use a full copper UTP Cat5 cable and not a copper alloy cable.

Ok.

But why is working with non PC based DVR?

 

I tryed both NTCS and PAL. - this was the first thing i did.

[survtech 0]

First i test one camera with passive blauns and 1 meter cable. The image is black & white. I test the same camera on 30 meters coaxial cable and i sow a perfect color image.

All the camera are power at 220V with source cables between 20-30 meters.

I also ask my supplyer and he answer me he heard about the problem and the main reason is the FTP cat5 cable. He told me i have to use a full copper UTP Cat5 cable and not a copper alloy cable.

Ok.

But why is working with non PC based DVR?

 

I tryed both NTCS and PAL. - this was the first thing i did.

What brand of baluns are you using? It sounds like they could be the problem.

 

Also, copper alloy CAT-5? Sounds like BS to me. As far as I know, all CAT-5 is solid copper wire. Plus we have never had a problem with any CAT-5 with any passive baluns for runs from approximately 100 ft. to well over 1000 ft.

[cctv_down_under 0]

It should e easy enough to test with another short cable of cat5 and your existing baluns....in answer to your question it is because the capture card requires 1.1v and the analogue screen only 1v so with a cheaper camera and anything affecting the original signal...baluns...cable.....copper...distance...you may be dropping below the threshold...if it worked on copper I would guess its the baluns, termination (twists near it) or the copper in the cat 5....run a small short peice of good quality cable and find out...i would also re terminate just to be sure..keeping the twists high.