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alisande_gw

Light switches and dryer affect TVs

alisande
9 years ago

My TVs (kitchen and living room) are less than five years old. I've noticed for quite awhile that when light switches are turned off (not on), the television sound is interrupted and a line of pixilation (if that's what it's called) appears on the screen for just that fraction of a second.

Tonight it became apparent that my electric dryer is interfering with TV reception too. The kitchen TV (which is nearer to the dryer) shows the same reaction as when a light is turned off, but when the dryer is running it happens over and over, every few seconds. On the living room TV, only the picture is affected--again, repeating over and over.

Do I have anything to worry about?

Thanks!

Comments (9)

  • randy427
    9 years ago

    It's normal if your TVs are on an antenna rather than cable or satellite dish.
    The arcing and sparking that takes place in most switches and motors causes a momentary distortion, or you could call it interference, in the electromagnetic signal that your antenna picks up for your TV sound and picture. The TV's digital processor can't make sense of the distorted signal so you get the pixillated result.
    Similar effects were had, though not always as obvious, with analog TVs. I remember not being able to watch TV at all while my sisters were using their hair dryers.

  • jreagan_gw
    9 years ago

    I wouldn't think a normal switch open would cause enough EMF to disrupt a TV signal.

    An open neutral somewhere can cause high EMF radiation.

  • alisande
    Original Author
    9 years ago

    Both TVs are on an antenna--on a tower once used for ham radio. Reassuring explanation, Randy, thanks!

    Jreagan, is an open neutral something that can be (easily) tracked down?

  • Ron Natalie
    9 years ago

    Well, it's easy to test for the open neutral A cheesy three light tester from the home centers will do it. If you don't find it, it can be time consuming to find but not overly difficult.

    Making sure the dryer is grounded properly (might be on a grandfathered three wire circuit) and replacing the switch may help. Also make sure your feed line is in good shape and the connectors are firmly connected at both the antenna and the TV end.

    This post was edited by ronnatalie on Sun, Oct 19, 14 at 12:59

  • alisande
    Original Author
    9 years ago

    My son, a ham radio operator for 20 years (and tower builder extraordinaire) put up the antenna and connected the TVs, so I'm confident they're in good shape.

    The washer and dryer have been in their present location only 5 years or so, but I can't say for certain how old the outlet is.

    Thanks, Ronnatalie!

  • Ron Natalie
    9 years ago

    I've got him beat. I got my first ham license in 1974. I've had an amateur extra class license (the highest available) since 1988.

  • alisande
    Original Author
    9 years ago

    Good for you! It's a great activity. Joe has his extra class license too. I've been going to hamfests with him for years, and finally decided to study for my own license this year. I got my technician class a few weeks ago (yay!), and immediately started studying for the general. At this point, that's as high as my ham ambitions go. :-)

  • pharkus
    9 years ago

    I wouldn't think a normal switch open would cause enough EMF to disrupt a TV signal.

    ... it would.

    I lived with just an antenna most of my life. Any light switch in the house would cause just a tiny bit of static -- but that was in the days of analog tv. A "tiny bit of static" on an analog tv is a tiny click and a couple "spots" on the screen for a half second. A "tiny bit of static" on a digital tv is a serious interruption in the bitstream and a confused processor!

  • Ron Natalie
    9 years ago

    Pharkus is right.

    The digital transmission is compressed and the information for a frame may be split across quite a time interval. You'll get visual artifacts (pixelization, goofy display) until the a new frame covers up the missing or corrupted data. It could take until the next i-frame.

    Furthermore, there's very little forward error correction. It's not really warranted in the bandwidth because occasional visual artifacts in such situations are considered tolerable.

    This post was edited by ronnatalie on Thu, Oct 23, 14 at 10:13

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