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Ceramic Capacitor Question

Discussion in 'General Electronics Discussion' started by MichaelM, Oct 25, 2012.

  1. MichaelM

    MichaelM

    7
    0
    Oct 18, 2012
    I have a bad ceramic capacitor (blue) labeled:

    "LY
    SL6KV
    47J"

    I know it's bad because it has a gaping crack through it. Also it came off my LCD TV's power board that I'm trying to repair.

    I have searched google for about two hours now and cant make heads or tails of it. I found a post on a different forum that had similar caps that had gone bad, but I don't completely understand how to "decode" this one. The other post's cap as the same LY SL6KV but is 27J.

    Any information is greatly appreciated! :D
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    47pF +/- 5%
    6000V
     
    Last edited: Oct 25, 2012
  3. MichaelM

    MichaelM

    7
    0
    Oct 18, 2012
    Thank you again CocaCola!
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,222
    2,696
    Jan 21, 2010
    When you say "crack" I assume you mean an irregular crack, not a nice neat one in the top of the capacitor.

    Some (especially high voltage) capacitors have these.
     
  5. MichaelM

    MichaelM

    7
    0
    Oct 18, 2012
    Yes, the crack is irregular/not symmetrical and it's a nice shade of brown with a liiiiiittle bit of blue left. Haha
     
  6. MichaelM

    MichaelM

    7
    0
    Oct 18, 2012
    I'm having trouble finding these capacitor. Digikey doesn't have any in stock and it looks like most manufacturers sell only in bulk.

    To compound the issue, most of the caps aren't fully to spec. I've found 47pF-6kV caps at +/-10% and at -25c ~ 85c...

    Here's the whole picture. I have an Apex LD4088 LCD TV that the video stopped working but the audio still works. I already bought a replacement TV but want to attempt a DIY repair of the Apex in hopes of using it as a monitor for my PC. I've looked through hundreds of Fixya and similar web site "solutions" before I cracked the TV open. After opening the case and finding the broken capacitor that is part of the backlight system I thought this might be a relatively simple fix.

    I could replace the entire power supply board for roughly $100 including shipping, but I just dropped just under $600 for replacement/upgrade TV and would like to try this repair for less than the price of the board. That being said...

    - Do you think buying a 47pF 6000V capacitor with a 10% tolerance and a max temp of 85c would be acceptable? Logically the answer is no. Since the capacitor that failed is better quality, something lower isn't going to cut it.

    - Does anyone know where to get a 47pF 6000V +/- 5% with a max temp of 105c that doesn't require you to get a quote for a bulk order?

    - Perhaps there's a way to use a couple of similar voltage/tolerance/temp caps to achieve the capacity required...cheaply?

    I would like to just find the capacitor and give it a go. I'm going to try checking the components along the line to ensure it wasn't something that caused the capacitor the fail other than it being cheap or old or just happening to go bad.
     
  7. MichaelM

    MichaelM

    7
    0
    Oct 18, 2012
    Also, I apologize if this is posted in the wrong thread :D
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    10% or 5% is probably not relevant. 85 ° instead of 105 ° - what is the actual temperature where this capacitor sits?

    A crack in the capacitor points to more than just a few degrees overheating. It is rather probable that the broken capacitor is only the symptom of another problem. So before you go on a shopping spree, try a 10% / 85 ° capacitor to see whether the TV works at all.
    If yes, you can still search for a higher quality capacitor.
    If no, you will have to locate the root cause that lead to the defect capacitor.

    Regards,

    Harald
     
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