Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Plasma TV busted?

  1. Aug 19, 2008 #1
    My parents have a 3yr old LG Plasma HDTV. Last month the color in the screen appeared to shift or fade. Then the screen started to flicker. Then the TV could be turned on with audio, but no screen, just black. The strange thing is that if we unplug the TV for a few hours and then plug it back in and quickly press the on button, the screen will come back, but still flicker. Any ideas?
  2. jcsd
  3. Aug 19, 2008 #2


    User Avatar
    Gold Member

    What kind of flickering, Greg? Could it be that the TV has an interlaced display and the interlace function is not working?
  4. Aug 19, 2008 #3
    It was like a rapid change in brightness (enough to induce seizure!). Not as if the screen was being turned on and off. The picture was always present.

    btw it always happens when we use the dvd player, so its not a cable box or signal problem.
  5. Aug 19, 2008 #4


    User Avatar
    Homework Helper

    With just the audio coming through, I naturally think check the cables since they are on different cables going to the set. At least try different input cables before running too far afield.

    You could adjust the brightness and see if that makes any difference. A dimmer picture being stable might indicate that it is something like the voltage sources for the screen. You could also check to see if there is any automatic brightness enhancement settings with the set. That makes it get brighter in brighter light and dimmer at night. It could be getting flummoxed and not able to decide on what brightness to display. Try turning it off if there is one.

    Otherwise if multiple sources are exhibiting the same problem - that is to say if you have multiple signals physically - one to one going in - dvd directly - cable box directly - not through the dvd or vice versa that gets selected in - then you may just have a problem with the internal electronics.

    For heat influenced problems you can stress the set by using a hair dryer say pointed at isolated spots - like at the connection to the set. If the problem occurs by locally heating up the connector before the set gets too warm then you may have isolated the problem at the input. It might expose a cold solder joint or imperfect connection at the cable input. Don't run the hairdryer on the electronics, however, as that could guarantee that you then have problems in the set. This step requires a little common sense not to outright roast it. (Plastic buckling or discoloring is an indication the heat setting is too high for instance.) Especially not in front of the folks.

    Failing all that, and of course if you can't convince your parents to want to spend more time on PF, call LG and maybe even ask a technician in the off chance they might give you a straight answer. Otherwise think "service guy".
  6. Aug 19, 2008 #5
    Here is a video of the tv in action (13mb)

    http://www.physicspost.com/tv.AVI [Broken]
    Last edited: May 3, 2017
  7. Aug 19, 2008 #6


    User Avatar
    Homework Helper

    If that's what you are getting for all sources then I'd say it's most likely in the TV and needs repair or replacement - whichever is cost effective.

    You might call LG still. Their technicians likely know which parts of the set fail most commonly and the symptoms - that is if you can ever get through to one that does know what they are talking about and not some voice in India.
    Last edited by a moderator: May 3, 2017
  8. Aug 19, 2008 #7


    User Avatar
    Gold Member

    Man! That's nasty-looking, Greg. With the fast pace of development in electronics, new models every marketing cycle, etc, it could be tough to find someone to service it. I punched in the Zip codes of several Maine towns (including one 100 miles distant) to see who services LG products, and I got only one hit - a little appliance place not far from here that is essentially a one-man show. Not too reassuring. Good luck!
  9. Aug 19, 2008 #8
    in addition to LoweyPions' heat tests as pointed above...
    If you have a can of compressed air ( the kind used to air clean computers ) you can try cooling sections of the electronics and you may luck out and find a component that is overheating.
    (The clean air will cool but not do any damage if again you use some common sense and not over do any one area.)

    It won't fix anything but it may isolate a problem that can be fixed.
  10. Aug 20, 2008 #9


    User Avatar
    Science Advisor
    Homework Helper

    Just a guess since I've never worked on a plasma.
    However, since plasmas need high voltage for the display that is the circuit I would check out first.
    On a regular CRT the ABL circuit (part of the HV function) would be suspect.
    You might get lucky and find a bad solder joint.
  11. Aug 24, 2008 #10
    hmmm suppose I'll just call the local TV guy, maybe he'll be able to fix it or atleast order a part.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Plasma TV busted?
  1. Plasma TV and LCD TV (Replies: 2)

  2. TV Brokedown (Replies: 3)

  3. Pc Tv (Replies: 12)

  4. Plasma or LCD TV? (Replies: 11)