Blown cap or no?

Discussion in 'General Electronics Chat' started by takusakura, Jan 29, 2014.

  1. takusakura

    Thread Starter New Member

    Jan 29, 2014
    2
    0
    I have a Vizio plasma tv that just stopped turning on. Pulled the power board out and sure enough one of the filter caps was obviously gone. I then proceeded to pull the board and check for any other signs of damage as from a top view of the board all the other caps looked good. As i got it off and flipped it over I noticed what appeared to be leaked electrolyte fluid from under some of the other caps in that same area, and heat damage to the pcb. But looking back from the top there doesnt seem to be any leakage from them and everything looks ok.

    Is this repairable? Is this electrolyte goop? Id really like to be able to fix this tv as it was free and any practice is good.

    [​IMG]
     
  2. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    764
    Hola taku,

    Small is good here.
     
    spinnaker likes this.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,061
    3,823
    I would clean the back of the board by wiping with 90% isopropanol (isopropyl alcohol). Then replace all of the big filter caps. The cap electrolyte is not super corrosive. The board should be fine.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    What I see is someone has already had a go at this board and may have replaced some of the electrolytic capacitors.

    Which capacitor are you referring to?
     
  5. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    Who tired to repair the board before ??
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,801
    1,105
    I agree with MrChips; some caps have already been re-soldered.
    The solder pads for C951 also seem to have come away from the pcb.
     
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    some cap juice is corrosive, I worked on a kenwood ham rig that had plated through holes eaten away by it. electrolytic caps are the most failed parts in everything I work on, from smps to large variable frequency drives, to everything else.
     
  8. takusakura

    Thread Starter New Member

    Jan 29, 2014
    2
    0
    I acquired this tv from my grandmother because she was having issues with it turning on. shortly before i got it she paid someone to fix it. He said the mainboard was shot and replaced it. It worked for about three months before having issues again, and she gave up and gave it to me. I looked under the hood and quickly found the problem. When the guy replaced the mainboard he snapped on the smaller caps leg. I re-soldered and she worked again.

    I'mnot sure who re-soldered the caps on the psu, when i looked at it i thought maybe an overload could have done that but im no expert. my guess is the broken cap on the mainboard started to make the psu caps slowly fail till the day it just stopped turning on. Just ordered all new filter caps with higher ratings, so hopefully this will fix it.
     
  9. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    What kind of caps did you order ???

    Also remember to stay close to capacitance rating but you can upgrade the voltage rating but watch out for different sizes and configuration too and stick with low esr and name brand caps from well know company..
     
  10. #12

    Expert

    Nov 30, 2010
    16,316
    6,818
    You might have caused yourself a problem. Low ESR is more important than installing extra capacitance. A higher voltage or temperature rating might get you a cap that is too big to fit the original hole spacing.
     
  11. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    and a higher voltage rating will cause problems in the future. caps used to be marked with WVDC, their working voltage, if ran much under voltage, they slowly reduce in capacitance. the electro chemical reaction what makes them work will fade.
    cliff
     
Loading...