LN32A450C1D No Power Blowing Fuses Fixed

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  • neilc6
    Badcaps Legend
    • Nov 2015
    • 1550
    • Canada

    #1

    LN32A450C1D No Power Blowing Fuses Fixed

    This TV has a BN44-00214A power supply used in several models and there are lots of posts on it. Will start a new one here. Thought it was going to be an easy cap replacement.

    TV had no standby power and a bulged CM858 680uF/25. After replacing the cap, there was still no power and I noticed the main 6.2A fuse was blown. I replaced it with a 8A, plugged it in and sparks flew.

    The blue ceramic cap by the big filter cap had one leg blown out as well as a jumper beside it. The big Samwa filter cap was also bulged (not sure if it was bulged before). A little research indicated the dried out, brownish glue had become conductive causing more shorts. I replaced the big cap with a used one from another board, replaced the jumper and resoldered the ceramic cap (tester said it was still ok). I scraped off all the glue the best I could. Salvaged another 6.2A ceramic fuse and tried a second time. No sparks but still no power and it appeared the fuse blew a second time.

    Did a bit of more investigating using clues from other posts and repair kits. Checking the bridge rectifier, there was a dead short between the + and - output pins which was traced back to a shorted QP801S (FCPF11N60 600V/10A). ICB801S (STR-A6159) could have been potentially damaged from the short but the fuse blowing could have protected it.

    I replaced QP801S temporarily with a 2SK3326 (500V 10A) from another board and the TV finally powered up.

    The ICL resistor is cracked (DSC_5D15) but measures 15 ohms instead of expected 5 ohm so I will need to replace this. Will order the correct FET but doesn't seem that 600V is necessary for the PFC since 400V is expected and 500V should provide enough headroom. I also forgot to install the old ferrite bead that was on the drain pin.
    Last edited by neilc6; 02-17-2018, 04:16 PM.
  • BunnyFooFooSR
    New Member
    • May 2018
    • 2
    • Canada

    #2
    Re: LN32A450C1D No Power Blowing Fuses Fixed

    The blue ceramic cap by the big filter cap had one leg blown out as well as a jumper beside it. Was a fighter tho soldered it from knee to hip back in and replaced jumper and fixed a couple of bad joints. All said and done working and in good order.

    Another dump Freebie!

    Comment

    • comptek
      Badcaps Veteran
      • Aug 2013
      • 606
      • uk

      #3
      Re: LN32A450C1D No Power Blowing Fuses Fixed

      Remove the glue from the start up transistor too bottom left hand corner with the big cap at the top in fact remove all components with the glue on clean off and replace it will fail again otherwise

      Comment

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