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any ideas on this???

Discussion in 'Beginner Electronics' started by Tim, Jan 7, 2007.

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  1. Tim

    Tim Guest

    Hi all,

    I am hoping someone here may be able to help me with solving an intermittent
    fault with our family TV....... PLEASE ?.
    It is a Phillips 21PT2012 / 79R and has what I think is the serial number
    of BZ000231 723707 on the back cover.
    The fault manifests itself as sudden loss of all picture, and light from the
    screen and loss of sound at the same time, anywhere from 5 seconds to a few
    minutes from switch on.
    This started a week or so ago, and a turn off seemed to fix it, and now it
    will not run longer than a minute or so without dying. It seems like the HT
    supply drops out suddenly,
    but as I understand it the power supply rails for all the circuitry on this
    type of appliance may very well all come from one switching supply, and a
    fault there could wipe out everything?
    I have a reasonable understanding of electronics, and a good Fluke
    multimeter, but no cct. diagram, and no experience with TVs. Any
    suggestions? I think that the set is about 4 years old, and I guess it must
    be some component that is built to a commercial standard starting to break
    down, but I was hoping that there may be hope rather than junking it?
    Thanks for any assistance.

    Tim
     
  2. Jack

    Jack Guest

    Sometime heat generating components can get flaky because of an accumulation
    of dust causes them to overheat.
    You might try opening the case and give it a good vacuuming. Of course the
    unit should be unplugged for an hour or so before you open it up. Also look
    for signs of overheating on any of the components such as discoloration or
    charring. The most common problem on power supplies is capacitors that get
    leaky which causes them to overload the resistors feeding them generating a
    lot of extra heat so if you find a charred resistor it is probably not the
    root cause of the problem.
     
  3. Jim Douglas

    Jim Douglas Guest

    ANd don't forget there is big, damm big, voltage in there that can kill you!
     
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