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

Repairing a rear-screen projection TV

  1. Feb 3, 2009 #1


    User Avatar
    Gold Member

    I've got this Toshiba 42H82 TV that the cat dragged in. Attached is a quick rough pic of what it's doing. I know it's difficult (and potentially dangerous) to repair a TV and wouldn't attempt to do it without a friend who knows his electronic repairs.

    Can this kind of thing be repaired? Ideas?

    Attached Files:

  2. jcsd
  3. Feb 3, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I had asearch for projection screen and wavy lines and it looks like a capacitor failure on one of the boards from what some other people have said.


    http://en.allexperts.com/q/TV-VCR-Stereo-1749/Toshiba-Projection-Wavy-Lines.htm [Broken]

    Seems to occur to 4 year old Toshibas a lot. I'd still seek professional opinion however.
    Last edited by a moderator: May 4, 2017
  4. Feb 3, 2009 #3
    no really a tv repair person myself, but it sorta looks like a sync problem. horizontal at least, and vert if it's "rolling". if you can find a burst capacitor by inspection, consider yourself a very lucky nerd.

    another thing that techs sometimes do (more like did) is run around and reflow all the solder joints. occasionally, you get what's called a cold solder joint with stress fractures and high impedance. but with newer surface mount components, i'm not sure this will be an option for you.
  5. Feb 3, 2009 #4


    User Avatar

    Staff: Mentor

    Kurdt's links look useful.

    Be sure to use a big enough Isolation Transformer when working with exposed AC Mains (and higher voltages!) like in TVs. And be sure your electronics friend can explain to you why an Iso is important...

    Also beware of high voltages being held on capacitors -- they can surprise you long after the TV is turned off. Do you have a SAMS Photofacts for the TV? You really need one of those before you start digging into the TV. Also, what is the anode voltage for the projection CRTs?

    EDIT -- Hmmm, doesn't seem to have a SAMS Photofacts edition for that TV.... Toshiba may not be cooperating...

  6. Feb 3, 2009 #5


    User Avatar
    Gold Member

    Cool. I'm finding the same links.
  7. Feb 4, 2009 #6
    If you can eyeball and find a defective component sometimes you can replace it. Heating soldered connections and resoldering a new component can easily ruin adjacent components...so use a modest size soldering appliance.

    I'm not expert either, but it looks like the projection illumination buld is still good..those can be quite expensive....if you buy a replacement circuit board and you open the package you'll own it...so check if the board you suspect is an expensive one....testing circuit boards on your own is typically not easy...if you have specs and test values and enough spare time and interest, it's not so bad.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook