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    BALUNS

    I know there are members here dabbling or savvy in audio/video as hobby or for earning a living.
    I hope I can chase them around to give me some pointers that would pluck me out of this muck.

    I have six surveillance cameras in the vicinity of my house’s exterior. There's not one single property theft in the neighborhood which someone might think "what for"?
    Well, I have been a camera freak. I like playing with these things.

    I also have three web-enabled internet cameras inside which I really haven't used that much. . .they are quirky. They are not giving me trouble though.

    Here is my problem.
    Out of the six outside cameras. . . the camera that is looking at the front door (the most important imo ) has been a PITA. This is one of the cameras using one pair of the cat 5 .
    This is specially needed for Halloween.
    All six cameras have BALUNS because of the distance from the monitor. All cameras are using cat5.

    BALUN =BALance/UNbalance.

    It's a small transformer gizmo that balances the unbalanced video signal that's travelling through the twisted cat5 cable.
    Cat5 is used instead of video cables. Switching to shielded coax is not an option.
    This is just a refresher . . . you guys are probably familiar.

    I have been changing this balun everytime it quits. Just like clockwork, the camera would work right after changing the balun. I've been changing this for over a year now. Camera runs on 12 vdc. Sometimes it lasts for months and sometimes only a few days.
    I have taken apart one of those that failed and I haven't seen anything that would lead me to track the problem. Of course I couldn't check the circuit board.
    There is one small toroid xfmr and a few tiny resistors and capacitors inside the unit

    It is working at the moment since the replacement from Amazon. Out of frustration.. .I ordered a dozen of these things as assurance.

    I've been fighting the problem—not solving it, which makes it frustrating.

    Why would this camera be eating baluns? I'm thinking mfg defect? Why so many failures.
    The rest of the cameras using these baluns have been working fine.

    If someone willing to share something that might help before I fall over the edge when I reach my wits' end, it would be awesome.

    As a side note:

    Since the power source is nearby (no obvious voltage drop) all Baluns are the passive type.





    #2
    Something like these?: https://www.amazon.com/Cable-Video-P...12081415&psc=1
    Master Electrician
    Electrical Contractor
    Richmond, VA

    Comment


      #3
      Never seen that problem. First thing I would have done is switch to another manufacturer for the baluns instead of ordering a dozen more!

      I have taken apart one of those that failed and I haven't seen anything that would lead me to track the problem. Of course I couldn't check the circuit board.
      Why not? You certainly could check the the toroid for an open/short which is the first place I would look. Then check the caps for shorts. Keep in mind that surface mount caps can fail short from mechanical stresses also, like stress put on the PC board by connectors. Another interesting thing to try is to measure the in and out resistances and compare them to a known good unit.

      Although it would be interesting to know how it failed, your solution (or road to) is another brand ultimately.

      Since this seems to be unique to this one camera, for giggles I would also check the camera output to see if there is any voltage on it.

      -Hal

      Comment


        #4
        No brilliant (or otherwise) solution, but a lot of questions...


        What kind of failure do you see? Loss of video signal? Noise? White or dark picture??


        If I remember correctly, one pair of the Cat5 is for power, another pair for signal. No chance of crossed wires?

        You have a 'power injector' that sneaks 12 volts onto the power pair; a similar thingy at the camera pulls the power from the adapter to the camera.

        What's the voltage at the power injector and at the connection to the camera, before and after a failure?

        I'm assuming that the power injector and the thingy at the camera have all connections required; at the camera end there's a signal connection and a power connection.

        You say you've looked inside one of the baluns-- socket for the Cat5 coming in, attached to a circuit board. One pair from the socket branches off to the camera power connection.

        Any possibility of a power surge 'juicing up' the power connection? Shouldn't (!) affect the balun &c, but Murphy loves a sure thing! Weird possibility-- power surge to the camera feeding a 'hot' signal back to the balun, and cooking a capacitor??

        I'm assuming no capacitor in the power connection to the camera!

        Are you sure the problem is at the camera end??

        More questions if I think of any! (:


        ps-- I'm assuming you're using the same camera at the door. Have you tried swapping cameras??

        Comment


          #5
          Besides what PaulMmn mentioned, have you measured the resistance between all 4 input and output terminals of the balun itself (differential pair, coax connector center pin & shield) on both good and failed units? Compare measurements between them. If continuity is lost on a bad one, perhaps DC current is flowing through the balun and causing a winding to fail.

          Just noticed Hal beat me to it on mentioning a continuity measurement of the toroid type balun
          Last edited by synchro; 10-22-19, 02:26 PM.

          Comment


            #6
            Synchro reminded me of something-- I think there is a variation on the signal injector that piggybacks the DC on the same pair as the signal... and both the injector and the camera end have capacitors to isolate the signal from the DC. In that case, a surge might zap a capacitor. Would that make the camera subject to DC coming in through the signal port?

            Search for >power injector balun< or >POE< (Power Over Ethernet). Lots of options on Amazon! Most using BNC connectors for the Video.

            ps-- do the failed baluns still pass DC??

            Comment


              #7
              Sounds like you're using analog cameras. Why not just change them out to i.p. cameras? You've got the cabling in place anyway.
              CIAO!

              Ed N.

              Comment


                #8
                Baluns are installed outside? Cheap? Baluns are passive devices, part failure rate is in millions of hours.

                Perhaps the baluns you are using do not have any conformal coating, and humidity and weather have caused losses to jump.

                When I install any commercial equipment outside, look at it to be sure the circuits are conformal coated. If not, spray with clear polyurethane.

                Other possibility is movement of connections, wire or connection breakage.

                Comment


                  #9
                  Originally posted by junkhound View Post
                  Baluns are installed outside? Cheap? Baluns are passive devices, part failure rate is in millions of hours.

                  Perhaps the baluns you are using do not have any conformal coating, and humidity and weather have caused losses to jump.

                  When I install any commercial equipment outside, look at it to be sure the circuits are conformal coated. If not, spray with clear polyurethane.

                  Other possibility is movement of connections, wire or connection breakage.
                  This particular balun is one of the pair that is mounted inside. . . right next to the monitor above the breakfast table. This is totally away from the elements.

                  The other (one of the pair) is the one mounted outside and exposed to the elements. . .it is however sealed from moisture incursion. This one is not giving me the problem--just the one inside.

                  And there is no movement whatsoever on both baluns.
                  The funny thing is-- since I replaced the last one that failed when I posted this topic, it hasn't missed a beat, making me suspect that that mfg defect is at play here, as others had suspected.

                  This was like two or three weeks before Thanksgiving. . . so, we'll see.


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