Trying to learn lcd power supplies

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  • electronicsurplus
    Badcaps Veteran
    • Jun 2012
    • 210
    • USA
    #1

    Trying to learn lcd power supplies

    I am trying to learn how LCD Power supplies and, how to properly diagnose them. I simply cannot understand what to check for when there is no 5volt standby

    Any help would be greatly appreciated

    Thank you
    This Forum absolutely the best and, the most helpful forum I have ever found anywhere. thanks to all the fantastic members here
    Help keep these from the landfills
    Tags: None
    • rievax_60
      Badcaps Veteran
      • May 2012
      • 897
      • australia
      #2
      Re: Trying to learn lcd power supplies

      I learnt much from the data sheets for the control ICs. The standby supply is usually designed around one IC that contains the SMPS controller and power transistor, usually a MOSFET.

        Comment

        • rievax_60
          Badcaps Veteran
          • May 2012
          • 897
          • australia
          #3
          Re: Trying to learn lcd power supplies

          I have just finished repairing a Philips LCD TV which had no standby 5V.
          I found that the schottky diode at the standby transformer's secondary was short circuited.
          I replaced it with a diode with the same specs, 3A/60V, which got the TV working again.
          When I checked the waveform on the diode's anode, I saw that the negative pulse was peaking at -60V, not good for schottkys so I replaced it again with a 3A/100V part.

            Comment

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