It’s been a little more than two years since my wife and I hired a professional to install some TVs and surround sound in our townhouse. I’ve noticed a few bugs over time and called on Michael Bonetti (he was not involved in original install) of Home Theater and Beyond in Merrimack, NH to help me identify the source of these problems and most importantly - advise me on how to solve them without spending too much cash.
We have some modest equipment in our 15x12 living room. A 42-inch LG plasma TV is mounted over the fireplace. The 5.1 surround sound system includes an in-ceiling center speaker, floorstanding left and right speakers, wall-mounted rear speakers and subwoofer. The components: Yamaha A/V Receiver, Sony DVD Player and Comcast HD Cable Box w/ DVR are housed in a standard closet. Everything is controlled by an RTI remote. All the equipment was purchased new except for the speakers and sub (Cambridge Sound Works) which are near the 10-year mark (more on the speakers later).
What’s Ruining My HD?
We are seeing some extremely annoying, rising horizontal lines on the plasma. The lines vary in color; red, green or even purple. Sometimes the lines are faint, other times it’s dark. This is happening about 95 percent of the time.
“It’s electrical. There’s electrical interference,” says Mike. “It’s like a 60 cycle roll.” The interference disappears when Mike disconnects the cable from the cable box, further proving the noise is coming in via the cable feed.
Appliances and dimmer switches can cause this type of interference, says Mike. We can’t pinpoint anything specific in my unit, but since there are four townhouses in the building, there’s a chance one of my neighbors is to blame.
If the cable feed is properly grounded to the house, I shouldn’t have an issue. Time to call Comcast. One tech paid a visit and confirmed our diagnosis. He wants to return with an electrical expert and work to solve the issue. Mike also recommends a power conditioner to help clean up the signal.
Interference aside, the picture remains crisp. If I ever decide to dabble in calibration, Mike suggests using the ISF Calibration Wizard DVD.
As for the TV’s placement over the fireplace, Mike assures me that due to the extended height of the mantle and because it’s natural gas and not wood burning, heat poses virtually no risk to the plasma.
On two occasions, we’ve had the receiver shut down in mid movie. In both instances (Iron Man and Dark Knight) the receiver quit right in the middle of an explosion or very loud scene. I’m smart enough to know the lack of ventilation in the component closet could be a problem, but I’m also lazy enough to leave it alone until something happens (for what it’s worth, since it was professionally installed this way - I figured it was ok).
“Your power supply is covered. You need ventilation in this thing,” says Mike in the same “you should know better” tone I use on my 4-year-old when he’s throwing Play-doh against the wall.
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