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Thread: Smearing picture?

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    Junior Member SCT's Avatar
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    Unhappy Smearing picture?

    Hi guys,
    Looking for some advice about how to fix a problem I'm having with a new camera.

    Background..Installed a new Pacom EVO-540 camera with a Seikou vari-focal lens mounted in a recessed dome housing.
    95m RG59 run on dedicated security cable tray (about half of the way, the rest is a pretty clear run through ceiling space staying away from power where possible).
    24vac supply

    Problem...The picture at the camera is fine, clear and sharp (tested with my test monitor and dome cover off as I cant put the dome in place during local testing due to the test leads). At the DVR however, strange things are happening.
    At first I connected the camera directly to one of the LCD monitors (input 2 on a 4 input monitor) in order to look at the picture and see if it needed any further adjustment and the picture caused the 16way screen (input 1) to ghost very badly.
    I changed the BNC thinking it may have been a bad termination.
    Now when I connect the new cable directly to the monitor I am getting a picture but the top edge of the picture appears smeared upwards (image at the top edge is stretched and blurred) - looks like about the top 1cm of the picture is all thats affected.

    Any thoughts??



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    Sounds like a signal quality issue. Is the coax really a copper centre conductor, or is it copper anneal steel? The cable quality is especially important considering that 100m is normally the max acceptable run for RG59.

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    Quote Originally Posted by SCT View Post
    Any thoughts??
    Couple of questions.

    1. What brand of LCD monitor are you using?
    2. Is the Camera powered from the same location as the DVR/Monitor?
    3. Have you tried testing the camera at the location with a small fly lead so you can put the dome on?

    Judging by the symptoms of ghosting and smear, I would be leaning towards a Ground loop/jitter fault as the ghosting of Cameo (1/16th the screen) 1 doesn't sound like a dome cover fault.

    Btw is the EVO-540 a IR day/night camera? If so, it may be IR reflection on the lens.(just a thought).

    Quote Originally Posted by madtech View Post
    The cable quality is especially important considering that 100m is normally the max acceptable run for RG59.
    RG59/U is good for 250m.

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    almost guaranteed to be an earth loop.
    get a Novaris isolation transformer. You should have one in the tool kit at all times as uoi never can predict where an earth loop will occur but it is often on long runs to a different building where the mains power and earth spike are on a different switch board.
    Plenty of info on the web if you want to know more
    They are not expensive
    Tim Norton

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    Junior Member SCT's Avatar
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    Thanks for the replies,
    @madtech:
    yep, solid copper conductor and braided shield. It is a composite coax/power cable purchased from Kobi (haven't used this particular brand before but it looks ok). As George noted, I have always used 250m as max run length for RG59 as a guide.

    @intelligeorge:
    1. Monitor used is existing Samsung 19" CCTV LCD with 4x BNC inputs (1 only in use from local DVR)
    2. Power supplies are in main switch room approx 15m away. Doubt if this is a problem as they are already powering other cameras (some on longer runs) that are working just fine.
    3. Dome is in the middle of a fixed ceiling area so unless I cut and join about 3m away fly lead is a pain (may try it anyway though just for positioning). Smearing occurs with dome on or off so the dome itself doesn't appear to be a problem.

    Judging by the symptoms of ghosting and smear, I would be leaning towards a Ground loop/jitter fault as the ghosting of Cameo (1/16th the screen) 1 doesn't sound like a dome cover fault.
    Not just the Cameo that was ghosting, it was the whole screen of all 16 cameras.

    Btw is the EVO-540 a IR day/night camera? If so, it may be IR reflection on the lens.(just a thought).
    yep, Hi-res d/n.

    @CCTVguru:
    I usually carry a GIT for service and testing purposes. Will check the back of the van for it as I havent had to pull it out for a while.
    Should it be installed at the camera end or at the DVR end of the run?

    I've seen other effects as a result of ground loops (picture shearing, ghosting etc, but have not come across this particular fault where it's only the top 1cm of the picture thats affected (smeared upwards, not sheared).


    Attending site again tomorrow so will let you know how I fared.
    Cheers,
    SCT

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    Junior Member SCT's Avatar
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    OK lets just put this one down to....degenerative brain cells.

    No dome cover = picture OK
    Dome cover on = smeared top 1cm of picture.

    I probably should have added in previous posts that the camera in its recessed housing was elevated (looking) upwards as far as possible in order to capture the required area of the scene.

    All of my casino points (gameroom cash) to the person with a few more working neurons than me who can tell me what the problem was. (hint..nothing to do with ground loops or voltage or camera setup) Easy as...now!!
    Last edited by SCT; 30-10-09 at 05:31 PM.

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