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15" LCD TV's

Discussion in 'Repairing Electronics' started by James111, Nov 6, 2008.

  1. James111

    James111 New Member

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    Hello to all. 2 years ago I purchased 14 Phillips/Magnavox 15" LCD tv's, refurb's, for school use. Since then I have had 3 of these go bad. It is always the same, first the video will go blank after 15-20 minutes, shut it off, wait a few minutes and turn it back on. It soon gets to a point where you no longer have any video ever but good sound. I see many of these sold for parts on the net so I believe there is a very common problem. Can anyone help me out as were to look or shed some light on these failure. I have pressed everywhere on the board while it is on to see if video would return but it doesn't. Thank you for any help, Jim
     
  2. picbits

    picbits Well-Known Member

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    As per the other thread with a similar problem, go through all the electrolytic capacitors first and test/replace the dodgy ones.

    They dry out with heat and age.
     
  3. picasm

    picasm Member

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  4. dave

    Dave New Member

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  5. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    With my monitor i had way too many electrolytics to go through all of them.
    I'd say there were about 50 in there. Some where for control and not
    power supplies, so if i only looked at the ones used for the power supplies
    (guessing a little as to which ones) i'd still have to go through about 20.
    Im not sure i wanted to desolder one lead of all those caps.
     
  6. Magen

    Magen New Member

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    Hello,
    Try looking at the caps closest to heatsinks/heat sources first. They're usually the first to go.
     
  7. James111

    James111 New Member

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    LCD TV's

    Thank you for your help. I have already paid and downloaded a diagram to assist in locating the problem. I'll check the caps suggested by other threads. again thank you , Jim
     
  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That's why you use an ESR meter, it checks the capacitors in-circuit, and checks for what goes wrong with them - you can also use a scope to check for ripple, but that requires it powered up and running.
     
  9. blueroomelectronics

    blueroomelectronics Well-Known Member

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    What program is that? It helps troubleshoot LCD TVs?
     
  10. picbits

    picbits Well-Known Member

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    I guess maybe he has found Euras or similar.
     
  11. Mikebits

    Mikebits Well-Known Member

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    Best tool for this type of problems is a can of Freeze spray and a heat gun. Works like a charm. This method only works when the set is temp-ermental :)
     
  12. James111

    James111 New Member

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    15' LCD's

    Tanks to all for your suggestions. I have given many of these a try but to no avail. I was hoping there must be a very unique problem that is common to all of these but sometimes it's not that easy. Since they were refurbs in the first place, it's hard to warrant a lot of time let alone parts locating. I just don't like to throw away the entire unit for just one small bad cap. More products today should be repaired instead of just chucking. Again, thanks for all the help, Jim
     
  13. francis10gh

    francis10gh New Member

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    did u check n replace the capacitor?
    u sould replace the long ic on the board.
     
  14. Mikebits

    Mikebits Well-Known Member

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    Of course you must realize, there is more than 1 cap on the board. Many to be exact.
     
  15. PaulAdman

    PaulAdman New Member

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  16. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi Nigel,


    Thanks for the great idea about the ESR meter. It's too bad i dont
    own one though, but if i did i would certainly give this a shot.

    Im not sure if it would pay for me to buy one just to fix this one CRT
    now though, and then if something else went wrong with it i would
    be a bit sorry :)
    It's too bad too because electrolytics arent that expensive and i
    have a bunch around already too.

    In the future i'll have to keep this idea in mind however, in case
    i spot a sale on an ESR meter.


    I have a wave generator and scope but im too lazy to try that.
    Also, i like the smaller space the LCD takes up now so maybe
    i'm hooked on LCD's now. In the future though i think i'll look
    for a better LCD as i seem to have gotten a cheapie now.
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    As you have a scope, check for ripple on the supply rails - this is mostly what low ESR caps cause.
     
  18. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi Nigel,

    Well the unit would not power up, that was the problem.
     
  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    The unit not powering up, and the PSU not powering up are VERY different things - are none of the supply rails working?.
     
  20. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi again,

    Well, now i gutted it for parts :)
     
  21. aquamon

    aquamon Member

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    Oh my.

    Oh my.

    Oh my.

    FAILURE!

    Mr. A1 Sauce?,

    If you have a DMM, get yerself a damned ESR meter or build one yourself (google it)!!!

    I myself bought and use a CapAnalyzer88A, couple years later I added another DMM from world-wide-wars dot mouser dot com, Amprobe 34XR-A.

    Some caps that pass with the CapAnalyzer fail with the Amprobe!!!
    :(
     

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