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    #1

    LCD Digital Screen monitor help

    Hi, first time at this great forum.

    Need help regarding a LCD Screen not working the backlight. Only dim picture on screen shown.
    Have made a photo of the PCB board and found that one of the transistor PNP (left side on photo marked) has a physical burn out.
    Cannot found the part number for both.

    TFT LCD Screen
    SUPER 808-6B2.PCB

    Please help.
    Attached Files
    Tags: None
    #2
    Re: LCD Digital Screen monitor help

    On the board the 2 diodes are marked Q3 & Q4,
    Q3 is burn out don`t know what D is
    Q4 marked D8-/F8,
    What is the replacement in pair for this diodes?

    Please help, seams no body want to answer to this post!!!!

    Comment

      #3
      Re: LCD Digital Screen monitor help

      Can you provide brand, make/ model, and or serial #?

      Comment

        #4
        Re: LCD Digital Screen monitor help

        Car Color LCD TFT DIGITAL MONITOR/TV
        SUPER - 808
        8" SCREEN

        808-6B2.PCB
        AXJ.05.29

        Comment

          #5
          Re: LCD Digital Screen monitor help

          I am having a hard time finding a schematic for the SUPER sp-808.

          Are you sure that they are diodes? Q denotes a transistor (MOSFET).

          Comment

            #6
            Re: LCD Digital Screen monitor help

            I think they are both drain voltage as they have marked with D letter, maybe a sot89 smd need the schematic for that.

            Comment

              #7
              Re: LCD Digital Screen monitor help

              I agree. They sure don't look like diodes (Q3 and Q4). A diode is D4 (just above the FCON cap on its side).

              Originally posted by cmj21973
              Are you sure that they are diodes? Q denotes a transistor (MOSFET).
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              Comment

                #8
                Re: LCD Digital Screen monitor help

                I see two connection that isn't properly inserted. The lamp connection isn't inserted properly. And the LCD screen is connected. just need to confirm you see that.

                Comment

                  #9
                  Re: LCD Digital Screen monitor help

                  Shoot, that's a Royer oscillator!!! Those are definitely NOT diodes, they're transistors. I don't know who made these transistors, but they can be replaced with a pair of the high gain rating Rohm 2SC4672. Also resolder the transformer and make sure that cap is in good shape and soldered properly.

                  PlainBill
                  For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                  Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                  Comment

                    #10
                    Re: LCD Digital Screen monitor help

                    Is there a logo on the part?
                    Mann-Made Global Warming.
                    - We should be more concerned about the Intellectual Climate.
                    -
                    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                    - Dr Seuss
                    -
                    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                    -

                    Comment

                      #11
                      Re: LCD Digital Screen monitor help

                      My guess is the package has two transistors in it, one D8 and one F8.
                      D8 = BCF33
                      F8 = BF824
                      .
                      Mann-Made Global Warming.
                      - We should be more concerned about the Intellectual Climate.
                      -
                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                      - Dr Seuss
                      -
                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                      -

                      Comment

                        #12
                        Re: LCD Digital Screen monitor help

                        the right transistor is in good physical condition and can see the device code as shown on the photo
                        the left side is bun out and the only device code is the letter D....



                        https://www.badcaps.net/forum/attach...id=16540&stc=1
                        Attached Files
                        Last edited by pug_dari; 06-27-2010, 01:14 AM.

                        Comment

                          #13
                          Re: LCD Digital Screen monitor help

                          Originally posted by PCBONEZ
                          My guess is the package has two transistors in it, one D8 and one F8.
                          D8 = BCF33
                          F8 = BF824
                          .
                          Bad guess. Compare this to the inverter on the Benq monitors. Here's a link to the Benq.

                          Large poly cap? Check! (C? - obscured by the lines)
                          Transformer with multiple (three) primaries? Check! (TR1)
                          Inductor? Check! (L1)
                          FET? Check! (8 pin package below IC4)
                          PWM? Check! (IC4) I say it's a TL1451 or equivalent.

                          I have seen the same circuit (using SMT transistors) in monitors by Viewsonic, Sceptre, and severach even found it in a rack mount Compaq monitor. Look here.

                          Those transistors can be replaced by Rohm 2SC4672, available from Digikey as 2SC4672T100QCT-ND at $.83 each.

                          PlainBill
                          Last edited by PlainBill; 06-27-2010, 06:54 AM.
                          For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                          Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                          Comment

                            #14
                            Re: LCD Digital Screen monitor help

                            Originally posted by PlainBill
                            Bad guess. Compare this to the inverter on the Benq monitors. Here's a link to the Benq.

                            Large poly cap? Check! (C? - obscured by the lines)
                            Transformer with multiple (three) primaries? Check! (TR1)
                            Inductor? Check! (L1)
                            FET? Check! (8 pin package below IC4)
                            PWM? Check! (IC4) I say it's a TL1451 or equivalent.

                            I have seen the same circuit (using SMT transistors) in monitors by Viewsonic, Sceptre, and severach even found it in a rack mount Compaq monitor. Look here.

                            Those transistors can be replaced by Rohm 2SC4672, available from Digikey as 2SC4672T100QCT-ND at $.83 each.

                            PlainBill
                            Those use 3-pins, this uses 4-pins.
                            Probably two transistors in one package with common base or common emitter.
                            Last edited by PCBONEZ; 06-27-2010, 07:21 AM.
                            Mann-Made Global Warming.
                            - We should be more concerned about the Intellectual Climate.
                            -
                            Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                            - Dr Seuss
                            -
                            You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                            -

                            Comment

                              #15
                              Re: LCD Digital Screen monitor help

                              SMD Codes
                              http://www.google.com/url?sa=t&sourc...kx8BJsyklcP0Rg
                              Mann-Made Global Warming.
                              - We should be more concerned about the Intellectual Climate.
                              -
                              Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                              - Dr Seuss
                              -
                              You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                              -

                              Comment

                                #16
                                Re: LCD Digital Screen monitor help

                                http://www.mikrocontroller.net/attac...V06_OE5VLL.xls

                                Updated SMD code list

                                Comment

                                  #17
                                  Re: LCD Digital Screen monitor help

                                  Originally posted by PCBONEZ
                                  SMD Codes
                                  http://www.google.com/url?sa=t&sourc...kx8BJsyklcP0Rg
                                  Looks like (roughly) the same specs as the 2SC4672. Certainly rated for lower power.

                                  It's the same frigging design as used by the Benq!!! Two identical NPN transistors in a Royer oscillator. A TL1451 gating a mosfet to control brightness (and perhaps current?). (No emitter on a mosfet).

                                  Look up the Belinea 101910 service manual.

                                  PlainBill
                                  For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                  Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                  Comment

                                    #18
                                    Re: LCD Digital Screen monitor help

                                    Originally posted by PCBONEZ
                                    Those use 3-pins, this uses 4-pins.
                                    Probably two transistors in one package with common base or common emitter.
                                    I finally figured out what you were saying. You were wrong. The identifier code covers all parts in a package. If it has D8 on one end and F8 on the other one of those codes is the identifier, the other is a date, production, or lot code. Also, the BCF33 is a different package - SOT-23. The package in the picture is the SOT-89 or MPT3 (Rohm's name for their SOT89-like package)

                                    The SOT-89 and MPT3 packages have only three leads. The tab is common with the middle lead. Look up the datasheets.

                                    PlainBill
                                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                    Comment

                                      #19
                                      Re: LCD Digital Screen monitor help

                                      Originally posted by PlainBill
                                      I finally figured out what you were saying. You were wrong. The identifier code covers all parts in a package. If it has D8 on one end and F8 on the other one of those codes is the identifier, the other is a date, production, or lot code. Also, the BCF33 is a different package - SOT-23. The package in the picture is the SOT-89 or MPT3 (Rohm's name for their SOT89-like package)

                                      The SOT-89 and MPT3 packages have only three leads. The tab is common with the middle lead. Look up the datasheets.

                                      PlainBill
                                      Except when it's made in China by a company that doesn't want their name on it.
                                      Mann-Made Global Warming.
                                      - We should be more concerned about the Intellectual Climate.
                                      -
                                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
                                      - Dr Seuss
                                      -
                                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                      -

                                      Comment

                                        #20
                                        Re: LCD Digital Screen monitor help

                                        Originally posted by PCBONEZ
                                        Except when it's made in China by a company that doesn't want their name on it.
                                        Now you are being silly.

                                        PlainBill
                                        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                        Comment

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