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Hi! I need some help!

Discussion in 'Troubleshooting and Repair' started by thefixer, May 21, 2013.

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  1. thefixer

    thefixer

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    May 21, 2013
    I am trying to fix a LED TV that used to turn on and off in a cycle and now it just won't turn on at all. I discovered the problem of bad capacitors in these TVs and decided to open it up and check them. At first glance everything seemed ok, but when I measured the ESRs of the capacitors I noticed that one was higher than it should ( 3.0 + ) compared to 0.8 in the other identical ones in the circuit. So I decided to replace it, the problem is that I cant find an exact replacement anywhere. Can anyone help me with this???

    It is a Rubycon capacitor, series TXW 450V , 21uf , 105C , and it says MS in parenthesis . (don't know what that means )

    Also, two metal jumpers near the cap seemed to be burned and/or rusty... I shall include a picture.
     

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  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Wow. They are really weird capacitors. I expect the whole circuit needs to fit into a very narrow space. You may have some trouble finding a replacement.

    If the other caps are in parallel and you measured the ESR in-circuit, then they too may have the same ESR as the "faulty" one.

    For such high voltage capacitors, ESR is unlikely to be as much of an issue as with (say) a 1000uF 10V filter capacitor on an SMPS.
     
  3. thefixer

    thefixer

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    May 21, 2013
    Yes, its a very thin LED TV. I'm not sure if they are in parallel, but I check all ESRs of all capacitors and the only one that has a "strange" one is that one. I thought this would be an easy task; Is there anyway that I can possibly get a similar capacitor that might work even if its not identical? I know using a larger voltage level its ok, but not if you use a different capacitance?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The problem is that they're long and thin. Perhaps you can find some 450V capacitors that are a smaller capacitance (say 4.7uF) having the same diameter (and obviously shorter). You could wire then in parallel as a long stick...

    You'd have to be careful to insulate the wires though.

    You need the capacitance to be about right. -25% to +50% is probably OK in most cases. However it's hard to be sure.
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
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