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Reader Question: Scrolling black bars

Matt Burns

Question: I am now on a regular basis getting faint horizontal lines scrolling up my TV (60" Sony LCD TV A20 series).... I have everything hooked up to a APC Battery backup system.... The lines were not there for a long time and now they are back. My guess is the lines are due to some kind of electrical interference. I was thinking about spending a ton of money for something like a Pure AV or something else high end to filter out any electrical noise, but was hoping for a much cheaper solution.


Good question Jamie and guess what? You are on the right track.

[click on for our explanation]

More then likely what you are experiencing Jamie is indeed something to do with your electrical system; more specifically your ground. It sounds like what you are experiencing is ground loop or "Hum Bars." This is the same type of interference that causes some speakers to hum; hence the name.

There are some simple ways to determine what is causing it and some easy steps to fix.

  1. Separate your interconnect cables from the power cords. You could be experiencing cross-talk between these cables.
  2. Unplug all of your equipment and turn the TV on. (Make sure you have a black screen) Plug each piece of equipment to their power source and then into the TV. Hopefully you will find what is causing this. If none of your audio/video equipment causes it, turn off everything on that breaker including lights and clocks and repeat the process. Light dimmers and fan controls are notorious for causing "hum bars."
  3. If it turns out to be your cable line, call your cable company and show them your findings. Make sure they fix it.
  4. If it is one of your set-top boxes, try new cables.
  5. Check the ground wire on the outlet and make sure it has a good ground. Note: please turn off the breaker.
  6. Use a power condition/surge protector with an EMI/RFI filter in it. This is not simply the same surge protector that you put on your computer but rather one that filters out this unwanted noise. You can find them in most audio/video stores and they will start over $50 and continue up over a $1500. Monster Power and Belkin Pure AV are good brands some models have the option of running a dedicated ground to the power conditioners themselves; make sure you do.
  7. If none of these steps solves the scrolling black bars contact an electrician to run a new dedicated outlet.
Hope this helps and if our readers have any other tips for Jamie feel free to drop a comment!

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