Bauhn B55-64UHDF-1117 SMART TV no display

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  • ezenia
    Senior Member
    • Jun 2020
    • 55
    • England

    #1

    Bauhn B55-64UHDF-1117 SMART TV no display

    Hi,

    I noticed a TV out on the street that had been thrown out. It was near my house, so I thought why not take it and have a look to see what is wrong with it. I'm not expecting to fix it, but I am curious enough to try and see if it's perhaps something simple (i.e. a simple board replacement). You can sometimes be lucky like that.

    Here's what happens:

    Plug power cord into outlet. A very faint sound can be heard coming from one of the components on the power supply board. Power LED is red which likely indicates standby.

    Press power button and light turns blue (probably indicating ON status). After this, that same component makes a more noticeable constant noise. I can't really describe it, it's like buzzing or chirping, just a constant sound that doesn't stop until power is cut. It's not deafening loud, but it is noticeable if you go closer to the component. Screen is pitch black. No backlight or anything like that can be seen upon power up.

    If the board is just plugged into the mains, it makes no sound at all. As soon as the main board gets plugged in, it makes a faint sound on standby mode and gets louder if I press the power button.



    The component that's producing the constant sound is marked on the screenshot. What is it? And what would cause it to make a constant noise? Does it explain why the screen is black?

    How likely is it to be a power supply board fault? I've seen some spare boards on sale that I'm considering if it is the power supply board. I guess I just want to have more information before I decide to purchase a spare board.

    I'm no expert on board repairs at the component-level, so actually fixing what's wrong on the board is out of my league at this time. If there's anything I can check with a multi-meter to verify if it's the power supply board, I am willing to do that.

    Appreciate any input.
  • dick_barton
    Badcaps Legend
    • Aug 2015
    • 6642
    • Wales

    #2
    Re: Bauhn B55-64UHDF-1117 SMART TV no display

    Can you post a larger photo. What is the board number. What voltages can you read at the connectors on the left of you photo.
    Willing to help but I'm no expert.

    Comment

    • ezenia
      Senior Member
      • Jun 2020
      • 55
      • England

      #3
      Re: Bauhn B55-64UHDF-1117 SMART TV no display

      I took these measurements from the power supply board with the TV powered on (solid blue light) and cables connected to the main board:

      LED+ = 212.9V stable

      +12V = 12.2V
      +12V = 12.2V
      BK/ON = 05.22V
      ADJ = 04.33V
      SGND = -002.6mV
      SGND= -002.6mV

      SGND = -003.4mV
      SGND = -003.4mV
      +5V = cable doesn't have any wire going to it
      +5V = same as above
      PS/ON = 04.11V
      +5VSB = 05.25V
      +5V = 05.23V
      +5V = 05.23V
      SGND = no wire connected
      SGND = no wire connected
      SGND = -006.3mV
      +12V = 12.22V
      +12V = 12.22V

      +24V = 24.95V
      +24V = 24.95V
      SGND = -006.0mV
      SGND = -006.0mV

      Power supply board says "MEGMETT PCB:MIP550D-CX4-REV1.0 2016.04.01

      Comment

      • ezenia
        Senior Member
        • Jun 2020
        • 55
        • England

        #4
        Re: Bauhn B55-64UHDF-1117 SMART TV no display

        I've just ran the flashlight test again. I was previously doing it after the TV had been on for a while.

        This time I got ready before powering on.

        I found that upon power button press, the "Bauhn" logo could be seen under the flashlight. It would halt at this logo for maybe 5-6 seconds before just going off. The power LED remains blue.

        EDIT:

        It appears the menu button is showing up after all.

        EDIT2: Still confused why there isn't any sound though. Other reports of this issue have both sound and image under flashlights. Yet, for me, it's no sound and no backlight (image only seen under flashlight).
        Last edited by ezenia; 01-06-2021, 03:36 AM.

        Comment

        • K6vbe
          New Member
          • Dec 2021
          • 2
          • United Kingdom

          #5
          Re: Bauhn B55-64UHDF-1117 SMART TV no display

          Mine had exactly the same issue! Turned out to be 1 bad led on the back light setup! Removed the whole half a strip bridged the connection and boom tv back on

          Comment

          • K6vbe
            New Member
            • Dec 2021
            • 2
            • United Kingdom

            #6
            Re: Bauhn B55-64UHDF-1117 SMART TV no display

            Originally posted by ezenia
            Hi,

            I noticed a TV out on the street that had been thrown out. It was near my house, so I thought why not take it and have a look to see what is wrong with it. I'm not expecting to fix it, but I am curious enough to try and see if it's perhaps something simple (i.e. a simple board replacement). You can sometimes be lucky like that.

            Here's what happens:

            Plug power cord into outlet. A very faint sound can be heard coming from one of the components on the power supply board. Power LED is red which likely indicates standby.

            Press power button and light turns blue (probably indicating ON status). After this, that same component makes a more noticeable constant noise. I can't really describe it, it's like buzzing or chirping, just a constant sound that doesn't stop until power is cut. It's not deafening loud, but it is noticeable if you go closer to the component. Screen is pitch black. No backlight or anything like that can be seen upon power up.

            If the board is just plugged into the mains, it makes no sound at all. As soon as the main board gets plugged in, it makes a faint sound on standby mode and gets louder if I press the power button.



            The component that's producing the constant sound is marked on the screenshot. What is it? And what would cause it to make a constant noise? Does it explain why the screen is black?

            How likely is it to be a power supply board fault? I've seen some spare boards on sale that I'm considering if it is the power supply board. I guess I just want to have more information before I decide to purchase a spare board.

            I'm no expert on board repairs at the component-level, so actually fixing what's wrong on the board is out of my league at this time. If there's anything I can check with a multi-meter to verify if it's the power supply board, I am willing to do that.

            Appreciate any input.


            Bad led on backlight

            Comment

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