RG-6 custom wiring issue with Q-See 16-camera DVR System

[dawgenstein 0]

Hi I am new to the forum and looking for some advice on troubleshooting some custom wiring to use with my new Q-See QSD2316L 16-channel DVR security system.

 

A bit of background:

The QSD2316L system comes with 8 QD28414 cameras (1/4" Sony Super HAD CCD that are PAL/NTSC compatible) and cables. I have successfully installed 3 cameras so far with the kit's wiring. The kit wiring is 60 foot long coaxial with BNC and power connection.

 

My house was prewired with RG6 coaxial and power wiring to 2 front door locations. I have successfully connected a 4th camera to one of the prewired locations by crimping my own BNC connectors to the coaxial cable and soldering the power connections.

 

Now my problem is the 2nd house pre-wired location. The Q-See DVR system keeps giving me a "video loss" error after all the connections are made.

 

Here is what I have tested:

1) power: using a multimeter I have verified that my power wiring to this location is the correct 12 VDC from the Q-See power supply along with the correct polarity on the inside connector.

 

2) coaxial wiring: to verify the custom-crimped BNC connections on both end of the cable, I connected my IBM Home Director video distribution system to the wiring at the end that goes to the DVR--to backfeed a private signal in the wiring. I have this private signal already fed to 2 other locations in my house (feeds an analog channel from elsewhere in my home entertainment system). I connected a TV to the end outside where the camera would be connected and verified that the signal transmitted as I was able to watch/hear the private signal. So, to me this proves that the BNC connectors and the coaxial cable is good enough at least to transmit an analog TV audio/video signal.

 

3) Q-See camera--I have tested with 3 separate cameras. All 3 work when hooked into the Q-See DVR with their wiring. None of these 3 work when connected to the wiring here.

 

So, power is good, the cable seems good in the opposite direction, but the DVR complains of signal loss. I am assuming that if the coaxial's center conductor was compromised in some way that it wouldn't transmit the private signal that I'm able to prove out.

 

What should I do next? I have chopped off 1 full set of BNC connectors already and gone back through all the tests above with no difference.

 

Is this a case of signal attenuation? How can I know? The wiring was done by the builder of my house and it is hidden behind the walls--I would estimate the cable run to be between 45 - 65 feet based upon the mounting length of one of the other cameras I mounted myself.

[Soundy 1]

While it SHOULDN'T be an issue with such a short run, check the power at the far end *with the camera connected*. It's possible that the voltage is dropping too much under load and causing the camera to shut off. If that's the case, check for an iffy splice on the power run.

 

Also, try connecting the camera at the other end, then run the DVR end of the wire into an A/V video input on your TV, and see if you get picture.

[shoreviewsecurity 0]

Soundy offers good advice above but you may try one more thing. If you have a separate plug in power supply, try powering the camera at the location it is installed. If the cam works then it would suggest a faulty power lead. If it does not, then I would suspect the coax to be the issue.

 

You may also try to ohm out the coax and power lead to see if they are damaged. What I have done in the past is to first, without any connectors on either end, attach an ohmmeter and read the resistance. It should read open. If there is a sheet rock nail through the wire you will see an indication of something other than open not unlike what you would get by touching the two meter wires together when set to read resistance. Remember, without any connectors on either end and by placing one of the meter leads to the shield and the other to the center conductor and the cable is not damaged, there is no path back to the meter. Somewhat like completing a circuit. I would do this for both wires coax and power.

 

Also, re-reading your post, I think by sending an analog signal through the coax may be misleading. The signal strength may be off setting the damaged coax. After spending over 20 years in the cable business, it depends on what frequency you are sending. I would suspect you are sending the signal from the IBM Home Director video distribution system on a higher channel say in the 70's?? Cameras use baseband video. In other words, and generally speaking, if the center conductor is compromised, you will see degradation on the lower frequencies whereas it usually will not affect the higher frequencies. Whenever I noticed the lower analog channels to be an issue, I immediately knew it was a dirty center conductor or bad splice.

 

I hope this made sense and please forgive me if I offended your knowledge in any way. Just trying to make it as clear as possible.

 

Thanks and good luck

 

Mike

[dawgenstein 0]

Soundy and Shoreviewsecurity,

 

Thank you so much for the replies. These are good next steps. You have not offended me at all--actually this level of detail is spot on. Although I got my undergrad in engineering I am not a practicing engineer--this sort of stuff is just a hobby from time to time and this is a DIY project for me. I was hoping for practical experience in real-world installation projects--so this advice is exactly the level I need.

 

I will do some more tests today and see if I can get resolution.

[Soundy 1]

Yeah, Shoreview's got some good tips too. One other thing I like to use to test: I keep a 75-ohm BNC terminator handy, that I can put on the far end of the line, and then meter across the other end, the way he suggests. That should then get a reading of around 75 ohms; anything significantly higher or lower indicates problems.

[dawgenstein 0]

Soundy and Shoreviewsecurity,

 

You guys were so helpful. I have it all working now! Drumroll,,,,,,,it was a faulty power wire. I backfed video from the camera end of the coaxial to prove that the coaxial for video was fine at both ends. I then honed in on the power side again. While my multimeter kept showing +12V DC outside, I moved the main power supply to the outside and connected the camera straight into the power unit. Voila. The camera came on and worked right away.

 

Then, as I was jiggling the wires it went back off. I inspected the power wire cabling a little more and noticed some nicks on the outside casing. I'm guessing when the house was built and they rolled up the extra wire they must have nicked it somehow. There was a lot of extra wire so I was able to cut behind the section which I believe was causing a short circuit on the power and re-soldered all the connections. Now it works just fine.

 

I have another question about this system that I will post now as a separate thread.

 

Thanks guys.

[shoreviewsecurity 0]

That's great news and I am sure Soundy would agree, it was a pleasure. I thought I heard what sounded like a drum roll here in New Jersey.

[soccerrmom33 0]

These are good tips, but any ideas on why a 8 CH q-see system which has worked for a year now would all of sudden show the Video Loss message?

 

I have tried to shutdown and restart the unit with no luck.

 

thanks!

[groovyman 0]

These are good tips, but any ideas on why a 8 CH q-see system which has worked for a year now would all of sudden show the Video Loss message?

 

I have tried to shutdown and restart the unit with no luck.

 

thanks!

Maybe the issue lies with the camera power source. How are the cameras being powered? Do they all have the same power source? Can you try connecting a camera directly to a monitor to see if you get an image?

[tomcctv 187]

These are good tips, but any ideas on why a 8 CH q-see system which has worked for a year now would all of sudden show the Video Loss message?

 

I have tried to shutdown and restart the unit with no luck.

 

thanks!

 

 

 

hi if all cameras are showing video loss then it points to your power supply. you can pick up a new one for a round $60 but i would look at this type that the small single unit with fly leeds from q-see.