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Toshiba TP61H60 Rear Projection TV Problem

Discussion in 'Electronic Repair' started by Tom, Nov 29, 2004.

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  1. Tom

    Tom Guest

    Hi,

    I am re-posting this one because of a computer problem that erased some
    files that had a detailed fix for this problem.

    My dad's rear projection TV, Toshiba TP61H60, has skewed blue only on the
    left middle of the screen. I remember that someone had said it was a
    convergence problem, but don't remember many of the details. Something
    about a bad IC.

    Could someone please help me out with this problem, my dad is retired
    with very little spare money. I do have good electronic skills and a
    couple of years of electrical engineering college.

    I can email pics if needed.

    Thank you,
    Tom
     
  2. Art

    Art Guest

    Probably the output ICs in the convergence circuit, maybe a few associated
    resistors, etc.
     
  3. Tom

    Tom Guest

    Art spoke thusly:
    Thanks Art.

    I can replace the output ICs. Does usage time destroy them or has something
    happened to do the damage? (ie. bad cap or resistor in circuit)

    Thank you,
    Tom
     
  4. Art

    Art Guest

    Normally these (STK) devices run moderately hot and tend to self destruct
    internally after a couple of years of use. Common problem not only in
    Toshiba sets but in all makes that use these devices.
     
  5. Jeff Rigby

    Jeff Rigby Guest

    While the STK devices have a high failure rate I don't think it's from
    overheat although I have seen them fail if enough heat sink compound isn't
    used. Most failure is from bad connections. The board to STK connections
    (18 of them) crack from metal fatigue (temp changes with dissimilar
    materials). IF the right connection opens the STK device will draw too much
    current causing it to fail and possibly open or change the value of
    resistors in the convergance circuit. Other pins with bad connections and
    you just get intermittent poor convergence.
     
  6. Tom

    Tom Guest

    Art started a controversy when he said... :
    I noticed that these two STK ICs and heatsinks are pretty close to the high
    output transformers. I suppose the added heat from them is not a good
    thing. Maybe adding a mica shield between them will help add some life???

    Thank you,
    Tom
     
  7. Tom

    Tom Guest

    Jeff Rigby stated:
    I will apply a fairly generous amount of compound when re-installing the
    new ICs. I will also reflow and add new solder to surrounding components.

    I really appreciate the added information.

    Thank you,
    Tom
     
  8. john

    john Guest

    Just put the required amount of compound on them .
    To much can be Bad.

    kip

    I will apply a fairly generous amount of compound when re-installing the
    new ICs. I will also reflow and add new solder to surrounding components.

    I really appreciate the added information.

    Thank you,
     
  9. Art

    Art Guest

    Did not mean to start any controversy, but have worked on too damn many of
    these items, seen the pcb discoloured because of the heat generated in this
    particular area, be it via the devices, defective solder, or a cat pissing
    on them, yes I've seen that excuse and effect also.<
     
  10. Tom

    Tom Guest

    john stated:
    Ahhh...correct, that is actually what I meant. Just noting that I wasn't
    going to be saving a penny on the heatsink compound. :)

    Thank you,
    Tom
     
  11. Tom

    Tom Guest

    Art stated:
    I'm sorry Art, that is the quote message in the news reader on the other
    computer. Not saying you started any controversy. :)

    I had a look and there is a bit of discoloration on the pcb in that area.
    These ICs have a fairly large heatsink on them and I was wondering about
    the heat generated by these ICs, so I don't doubt your thoughts on heat.
    I am wondering if there is a correction/fix that would increase the life
    of these components.

    Thank you,
    Tom
     
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