Emerson LF501EM4 DS4 no standby led

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  • videotronics
    Member
    • May 2013
    • 22
    • USA

    #1

    Emerson LF501EM4 DS4 no standby led

    faint chirp when menu button pressed

    all3.3v pulsing to .5v on 2 seconds

    disconnect ribbon to mainboard
    all3.3v 3.3v

    connect ribbon to mainboard
    resistance all3.3 to ground 810 ohms

    disconnect ribbon to mainboard
    connect all3.3v to p-on_h2
    p-on+21v 20.9v
    amp+13v 12.5v
  • CapLeaker
    Leaking Member
    • Dec 2014
    • 8120
    • Canada

    #2
    Re: Emerson LF501EM4 DS4 no standby led

    Well, sounds like the main board is dragging the psu down. What is the resistance on the main board from stby to gnd?

    Search for your model number in badcaps. There is one thread not powering on. It has a schematic for your TV. There are a number of reasons why the main board could load the 3.3v rail down. One would be the little ir board, another one could be the zener diode on the tv module is short to gnd, etc...
    Last edited by CapLeaker; 04-03-2020, 08:22 PM.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Emerson LF501EM4 DS4 no standby led

      You may have shorted cap on the main board.
      Reconnect the cable between main board and power supply board then check the resistance between GND and p-on+21v, amp+13v 12.5v to see if any one of them shows low resistance reading, report the readings.
      You may have the typical bad cap C3214, c3943.
      Last edited by budm; 04-03-2020, 08:55 PM.
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

      Comment

      • videotronics
        Member
        • May 2013
        • 22
        • USA

        #4
        Re: Emerson LF501EM4 DS4 no standby led

        connector on resistance to ground
        P-ON+21v 26k ohms
        AMP+13v 6.6 ohms
        ALL3.3v 810 ohms
        connector off resistance to ground
        P-ON+21v 26k ohms
        AMP+13v 1.75 Mohms
        ALL3.3v 810 ohms

        assuming overload on the AMP+13v supply looking at audio output IC3801 and peripheral electrolytic filter capacitors C3829 and C3831

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Emerson LF501EM4 DS4 no standby led

          Does your main board have C3214, c3943?
          Please provide Pictures and P/N of your main board.
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

          Comment

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