Samsung BN44-00438B LCD TV Power Supply

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  • craigc15
    Senior Member
    • Jun 2012
    • 53
    • USA

    #1

    Samsung BN44-00438B LCD TV Power Supply

    Hi Folks!
    I've searched high and low for a schematic of this Samsung (Hansol) power supply to try and figure out what the devices are in the gate drive circuit for the backight inverter h-bridge.
    Both MOSETS read open D-S.
    One of the G-S zener diodes was shorted, the other reads open. I need to know what their zener voltage is. I suspect somewhere around 10 volts.
    There are a few resistors that have changed value, and I think I have the right numbers off of those resistors.
    There are these other devices identified as B1803 and B1804 that are in series with the gates. One reads shorted and the other one, which is cracked, is reading around 280k ohms. There are no identifying marks on these devices.
    Any thoughts on what they might be?
    A schematic would really be nice, too!

    Thank you VERY much for any help you can provide!
    Craig
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Samsung BN44-00438B LCD TV Power Supply

    G-S zener will be around 18~27V.
    Exact value is noncritical but must be less than MOSFET Vgs(MAX) (typically ±20-30V) and more than the controller chip Vcc.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • DiAngelo
      New Member
      • Nov 2013
      • 1
      • Croatia

      #3
      Re: Samsung BN44-00438B LCD TV Power Supply

      Hi craigc15

      Do you maybe solve your problem and perhaps you know what transistors ( Q1801 & Q1803 ) are used?
      Also, do you maybe know value for R1842 and R1845?

      Thank you very much for any help

      Rikardo

      Comment

      • Ltank
        Badcaps Veteran
        • Jun 2013
        • 776
        • USA

        #4
        Re: Samsung BN44-00438B LCD TV Power Supply

        I could not find a schematic for the BN44-00438B . What is the Model ? or Chasis # ?

        Comment

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