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tv blows fuse

Discussion in 'Electronic Repair' started by Steve45, Mar 29, 2007.

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  1. Steve45

    Steve45 Guest

    hi folks i'm new to this forum and have a question . i have a sylvani
    srt2127s that blows the fuse as soon as i plug it in. I just starte
    messing with busted tv's as a hobby because i recently had surgery fo
    a work related accident and needed something to keep my mind and m
    hands busy. I just fixed an old sanyo that just needed a couple o
    capacitors and now i'm trying my luck with the sylvania.please talk i
    layman's terms as i am not tech educated. pictures or diagrams of part
    to check or replace would be very helpful. thanks,wish me luck
     
  2. Hi,
    Your description indicates a "primary-side" failure, in other words,
    the side which is not
    galvanically isolated from the mains and need great focus to not kill
    yourself during repair.
    A wild guess, would be a shorted input rectifier or a shorted
    switching transistor in the TV's switchmode powersupply.
    I've even seen damaged mainscords with internal shorts! Maybe a dog
    chewed on it. This would of course lead to a fuse blow before pressing
    mains switch on the set.
    I'm not familiar with this specific set, but that's general TV tips.

    Good luck!

    --- Steve
     
  3. James Sweet

    James Sweet Guest


    Well assuming he's in North America, the mains plug is not fused. The
    only circuit protection we have here aside from the fuse in an
    individual piece of electronics is the 20A breaker on the branch circuit.
     
  4. Arfa Daily

    Arfa Daily Guest

    I would agree with this basic diagnosis, and would also seek to reinforce
    the advice regarding safety. If you are new to this, you absolutely MUST
    gain some understanding of the dangers of switch mode power supplies, and I
    would strongly recommend that you do some internet research on this aspect
    first. They honestly are potentially lethal in inexperienced hands, and can
    still give you a VERY powerful shock, even hours after they have been
    switched off, with some fault conditions. You might like to cover your eyes,
    or turn your head away when you switch on, also. It is not at all uncommon
    to have the chopper transistor explode its side off, or the wrong type
    (glass) fuse shatter explosively. If you are intending getting to grips with
    these, I would recommend at a minimum, fixing yourself up with a proper
    bench isolation transformer, to offer yourself at least a degree of personal
    safety.

    Arfa
     
  5. I believe he means the internal fuse in the set, don't you think?
     
  6. b

    b Guest

    I agree with the other posts in this thread. May I add that a quick
    initial test might be to disconnect the degauss coils from where they
    plug into the circuit board (they're the loop of plasticky wire going
    round the back of the tube near its perimiter). power up and see. you
    may need to replace the 3 legged (or sometimes 2) posistor.
    incidentally, it is advisable to wire a 100w bulb in series with the
    mains input - over the internal fuse maybe. if it shines you still
    have a dead short; if not then you're probably OK, that way you save
    fuses.
    -B.
     
  7. Meat Plow

    Meat Plow Guest

    Well I'll wish you luck with your recent surgery as I'm going through the
    same thing myself but when it comes to repair, skill and knowledge usurp
    luck. Look in the power supply (smps)for shorted diodes or switching
    transistors. Be warned that to the novice like you, an smps can be
    dangerous and possesses potentially fatal voltages.

    --
    #1 Offishul Ruiner of Usenet, March 2007
    #1 Usenet Asshole, March 2007
    #1 Bartlo Pset, March 13-24 2007
    #10 Most hated Usenetizen of all time
    Pierre Salinger Memorial Hook, Line & Sinker, June 2004
    COOSN-266-06-25794
     
  8. James Sweet

    James Sweet Guest

    Yes, I'm pretty sure he does. I was replying to another response to his
    post.
     
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