repair tip?

Discussion in 'General Electronics Chat' started by Thomas.R, Jul 13, 2008.

  1. Thomas.R

    Thread Starter Member

    Aug 16, 2007
    20
    0
    Hallo

    As i am trying to fix a tv (see other post) i wondered if i could like isolate the power supply and pull out all of the cables and measure it with no load and if that part is good, connect another component and check if thats good and so on. couldn't this give problems or faulty measurements when there is no load?

    thomas
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Don't.

    Apart from the dangers involved in poking about inside a TV because of high voltages,
    modern units have switched mode power supplies which can be destroyed by running them on no load.
     
  3. theamber

    Active Member

    Jun 13, 2008
    318
    0
    Hi, for what I can put together is that:
    Tv has no image (black screen, no snow).
    It is a CRT TV.
    Tv turns on LED comes out and you feel the high voltage on the screen (like if you put the back of the hand you feel the hairs sticking out).
    First these fellows are right, there are a lot of stupid people out there, so be very careful with the high voltage section around the flyback transformer and the neck of the CRT!. Always use an isolation transformer!.
    Have you tried to hit the printcircuit board with the back of a screw driver to see if there is a cold solder joint?
    You most likely have a video problem and most likely is not comming from the power supply.
    You need a schematic, measure the voltages going into the video processor IC, video driver transistor and supporting components . To see the signals you will need an oscilloscope.
    You can get more information on this page that has solutions for the most commom problems.
    http://www.e-repair.co.uk/faults
    Good luck.
     
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