Two Scrolling Bands Usning Component Video Distrubtion Amp

Discussion in 'Home Theater Projects' started by David Proud, Apr 9, 2005.

  1. David Proud

    David Proud Stunt Coordinator

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    Two Scrolling Bands Using Component Distribution Amp

    I have 2 scrolling bars/bands that move from the bottom of the screen to the top of the screen when using a video-storm hdtv cb003 distrubtion amplifier.

    My setup consist of the CB003 HDTV component Distribution Amp sending 1 output to a HDTV upstairs and 1 to a lumagen HDP video processor that sends it to my projector in the theater room. The equipment rack is close to the main AC panel and I have no other place I can put this stuff.

    no bars exist on any other sources.
    If I run the HDTV box directly to the Video processor no hum bars at all.

    I know you will say this is a ground loop but I don't think it is. this is why, I have taken the CB003 and placed it on the same circuit as my projector, hdtv box, and video proecessor and the two bars are still there although at a slower speed.

    I hate Lots of Dimmers in the house. so I even went to the trouble of flipping every breaker in all breaker boxes except the ones in the theater room. Still scrolling bars.

    I bought a seperate Amp and Inday but it exhibits the same problem. They both use the same power supply and prob share the same internals.

    Inday support is going to send me a modified regulated power supply to see if that helps. Anyone recoomend anything I can do to fix this annoying problem?


    Any idea what I can do to get clean component HDTV distribution without the bars?
     
  2. Orlando

    Orlando Stunt Coordinator

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    Do you have a cable TV box/wire anywhere hooked up to this stuff. I had the same problem and it turned out that the grounding the cable wire was using and my house ground was the problem.

    It took me a week to find out what my problem was. It was right after a small upgrade and caused me to rip everything out and start from the beginning. A quick easy way to test would be to disconnect the cable wire that comes into the house off the usual ground block or coupler on the outside of the house and see waht happens.
     
  3. David Proud

    David Proud Stunt Coordinator

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    Yes. I even removed the coax cable feeding into the Cable box and the bars still existed. So the two bars are not coming from the cable tv cable.
     
  4. Orlando

    Orlando Stunt Coordinator

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    Sorry I edited my post after you sent your reply. Try what I said about disconnecting on the main entrance to the house so that nothing in the house is connected to the cable ground. I did the same thing, disconnected just the cable box, that is why I ended up ripping everything out. Cause it was driving me nuts. Somewhere in the loop the cable ground was still connected. It is an easy test and can't hurt. Disconnect the whole house from cable and see what happens.

    And Good-Luck I know these things are a pain in the butt to find and drive you nuts.
     
  5. ChristopherDAC

    ChristopherDAC Producer

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  6. David Proud

    David Proud Stunt Coordinator

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    yeah I just tried what you suggested and disconnected the main cable feed into the house. Still bars.

    The only way I can get the bars to go away is removing the distribution amplifier and running the cable box straight to the video processor.

    Also I noticed today as I moved the hdtv component distribution amps power adaptor cable around the speed and the intensity of the two bars changed but I could never get them to go away.


    Christopher where is this voltage regulation leaking, in the cheap power supply powering the distribution amp or inside the amp itself? I wonder if just upgrading to a regulated power supply would fix my issue!
     
  7. Leo Kerr

    Leo Kerr Screenwriter

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    A second possibility.

    Note, I'm not familiar with this particular box, but I'm supplying this based on past experience with video DAs in general.

    Looking at the other stuff on the Inday web-site, this is likely a 1x4 DA - one input, four outputs.

    It may be having termination issues because you're only using two outputs. If you can get a couple of 75ohm terminators for output 3, that may help.

    Barring that, one of your devices might be causing trouble - if both of your displays are on at the same time, do you get the bars? Again, possible termination issues.

    Hum-bars are one of the worst things to have to chase down; they can come from all sorts of things that shouldn't. I wish you luck..

    Leo
     
  8. ChristopherDAC

    ChristopherDAC Producer

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    I would never try to run a video amp without a clean power supply. How does this setup work? If you are running DC from a wall-adaptor type power supply into the distribution amplifier, it is a cinch the +9V DC or whatever it is has a significant degree of
    "ripple". Since the power-line frequency is very close [if not identical] to the field rate of the video, but not synchronised with it, the change in the input voltage [not to mention any RF the power line may be picking up] will produce rolling noise. If there's not at least one sizable filter cap at the input to the distro amp box, plus a couple of Zener diodes and a good RF choke, I would consider getting a slightly better power source and a shielded power cord. And as Mr. Kerr suggested, terminate all unused connexions at 75 Ohms for best results.
     
  9. David Proud

    David Proud Stunt Coordinator

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    where could I find a good power supply and what brand would be good. i need one that is 12vdc and atleat 500ma with positive tip polarity and p5p plug.
     
  10. David Proud

    David Proud Stunt Coordinator

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    Ok I hooked the Distribution amp up to a belkin UPS with the power off so full on battery and I still get the rolling lines, is this confirumation that the power supply is creating the rolling noise?
     
  11. David Proud

    David Proud Stunt Coordinator

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    IT WAS A GROUP LOOP but is this safe?

    I got 2 cheater plugs at home depot and plugged one into my projectors circuit and 1 into the video processor and the ground loop is now gone. If I just had a cheater plug in the video processor end still a ground loop existed, if I had a cheater plug in the projectors end but not the video processors end a ground loop existed. The key was getting the video processor and the projector both on a cheater plug.

    I don't wanna leave the cheater plugs on b/c I am concerned with saftey.

    What is so strange about the issue is I plugged every single thing ifrom my projector to the video processor nto the same powerstrip and the ground loop still existed.

    What can I get or wire to ensure saftey but yet keep the working configuration I have.



    POST #13
     
  12. Orlando

    Orlando Stunt Coordinator

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    David,

    It might be something else that is not plugged into the power strip. Like if you have a cable splitter and it is hooked up to another TV thus another power connection. I know it is crazy but you might want to check that out. Again Good-Luck and please let us know what the source is.
     
  13. David Proud

    David Proud Stunt Coordinator

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    i figured it out it was indeed a ground loop. I lifted the ground on both the projector and the video processor and that solved the problem. to be safe I am going to have installed gfci outlets on any ground I lift.
     

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