LG 55LM6200 buzzing / humming power board

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  • notallbad
    Badcaps Legend
    • Oct 2012
    • 1183
    • UK

    #1

    LG 55LM6200 buzzing / humming power board

    Having replaced a brand new full led backlight set and fixing a mainboard fault (power-on transistor) theres now a louder than normal hum / buzz coming from the power board in the AC filter, namely in the LF101 / 2 area, or at least thats where the sound is more resonant whilst the backlight is set at 100%. Turn down the backlight to 50% its less noticeable and 0% its non-audible.

    When the rear case is fitted back on its more audible and its certainly more than an acceptable level so would rather solve than leave like it.

    Have powered on the tv with panel disconnected from the t-con and sound persists so think this eliminates the panel.

    Have started reflowing some of the solder joints on the AC side but sound still persists.

    I cant find it now but I came across a method to modify the led driver circuit, anyone know the fix or can direct me to it? thanks. I know this may not cure the problem but may be worth doing also.

    PSU board : EAX64310801 (1,3)
    Attached Files
    Last edited by notallbad; 12-04-2024, 07:06 PM.
  • notallbad
    Badcaps Legend
    • Oct 2012
    • 1183
    • UK

    #2
    So found the culprit, a failed diode D607 MUR460.
    Replaced and now buzzing gone! Back down to a susceptible level.

    Comment

    • KYBOSH
      Badcaps Veteran
      • Oct 2011
      • 581
      • Unknown

      #3
      Originally posted by notallbad
      So found the culprit, a failed diode D607 MUR460.
      Replaced and now buzzing gone! Back down to a susceptible level.
      Failed or failing?

      Comment

      • notallbad
        Badcaps Legend
        • Oct 2012
        • 1183
        • UK

        #4
        DMM diode test showed as shorted both ways.

        Comment

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