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    Philips 37MF321D No power no LED

    Philips model # 37MF321D
    I am having trouble figuring what is going on with this television.There is no power and no LED
    Following the trouble flow chart has me wondering if it's correct.
    The service manual looks like it's for a 26 and 32” model, with a supplement for the 37 and 42” models. The connectors for the scaler board appear to be different, but the supplement for the 37” power board is correct.
    The service manual is available at Elektro Tanya.
    On connector 1089 I have,
    Pin #1 16v
    Pin#2 16v
    Pin#3 24v
    Pin#4 .8v
    Pin#5 0v
    Pins # 6-7-8 are 0v
    Pin#9 0v and
    Pin#10 is 0V
    Pin # 9 appears to be standby but its not mentioned in the flow chart; I am thinking I should see a voltage on that pin?
    Attached Files
    Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

    #2
    Re: Philips 37MF321D No power no LED

    I looked at the diagram, the STANDBY PIN is the control pin from the Main board that when it goes high (3.3~5vdc) it will turn on the PFC circuits which will kick the voltage on the that large cap (120uf 450vdc) from 170vdc (when it is in standby mode) to about 400vdc when it is in the ON. Since you are not getting the logic high from the main board on pin 9, you should verify the connection back to the main board.

    Failed TV's and Monitors:
    http://s807.photobucket.com/albums/yy352/budm/
    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


      #3
      Re: Philips 37MF321D No power no LED

      I still do not understand this,
      Should standby voltage on pin #9 be high any time power is applied to the main board? Or does something else have to occur to take the voltage high?
      Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

      Comment


        #4
        Re: Philips 37MF321D No power no LED

        When you hit the power button on the TV or using the remote to turn on the TV, the main board will send out the logic high to pin9 to turn on the PFC circuit that is when TV will change from stanby mode to ON mode. The main board is always on 24/7 the minute the TV is plugged into the outlets but it will be in standby mode (pin 9 is LO). This TV does not have 5vdc standby, but it uses the 16vdc that is always on.
        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


          #5
          Re: Philips 37MF321D No power no LED

          Originally posted by budm View Post
          When you hit the power button on the TV or using the remote to turn on the TV, the main board will send out the logic high to pin9 to turn on the PFC circuit that is when TV will change from stanby mode to ON mode. The main board is always on 24/7 the minute the TV is plugged into the outlets but it will be in standby mode (pin 9 is LO). This TV does not have 5vdc standby, but it uses the 16vdc that is always on.
          So it looks like the problem is on the main board?
          Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

          Comment


            #6
            Re: Philips 37MF321D No power no LED

            At this point, yes, since it is not putting out the PS_ON signal. Since you have the service manual, you can try locating where the signal is generated from in the service manual.
            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


              #7
              Re: Philips 37MF321D No power no LED

              The manual is for the 26 and 32” televisions.
              The problem is that the power and main board is different for the 37 and 42”.
              They did include a supplement for the 37 and 42” power board but not for the main board.
              I see a 5v and 3.3v LDO regulators on the main board, I guess I can hope one of those are bad.
              Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

              Comment


                #8
                Re: Philips 37MF321D No power no LED

                Yes, start checking voltages, that is what I will do after board inspection.
                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


                  #9
                  Re: Philips 37MF321D No power no LED

                  I too have the same set in magnavox,same problems, I think its signal board too,pricey guess,bought another set ,I can say that even working set has no standby light just green light when working nothing when off

                  Comment


                    #10
                    Re: Philips 37MF321D No power no LED

                    One thing to watch out for, Philips often uses the 'Label = function when high' convention. That is, the label (Standby) indicates the power supply is in standby mode when the Standby line is high. BUT they aren't consistent about it.

                    The best way to test it is to disconnect the main board from the power supply, then use a resistor (anything between 2.2K and 3.3K) between 5V_SB and Standby. If that doesn't bring the power supply to life, try using the resistor to pull Standby to ground.

                    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


                      #11
                      Re: Philips 37MF321D No power no LED

                      In this case, per SCH, the HI signal from main board will turn on Q7076, which will turn on the OPTO, which will turn on Q7063 which will supply the VCC voltage to the PFC Cotroller IC.
                      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


                        #12
                        Re: Philips 37MF321D No power no LED

                        Here is the SCH of the power supply.
                        Attached Files
                        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


                          #13
                          Re: Philips 37MF321D No power no LED

                          I do not notice 5v on any of the connectors on the power supply.
                          Do we want to try to turn on the power supply with applying 3v on the standby pin? And if that doesn’t work try grounding the standby pin?
                          Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                          Comment


                            #14
                            Re: Philips 37MF321D No power no LED

                            If you've got no standby voltage, then that's the first place to start fixing. The rest of the supply probably won't work without that.
                            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


                              #15
                              Re: Philips 37MF321D No power no LED

                              There is no 5vdc standby in this power supply, it has the always on 16vdc power supply that feeds the main board, this 16vdc will be used in the stepdown switching power supply circuits (5v, 3.3, 2.2, etc.) in the main board to run the main board , see page 20 of the service manual.
                              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


                                #16
                                Re: Philips 37MF321D No power no LED

                                Originally posted by budm View Post
                                There is no 5vdc standby in this power supply, it has the always on 16vdc power supply that feeds the main board, this 16vdc will be used in the stepdown switching power supply circuits (5v, 3.3, 2.2, etc.) in the main board to run the main board , see page 20 of the service manual.
                                Okay. That's strange for a 37". Usually there's a separate standby supply to comply with low power consumption mandates. (Blue Angel, etc.)
                                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


                                  #17
                                  Re: Philips 37MF321D No power no LED

                                  Philips does thing in its own way, it may have been made before the mandate comes along, at least they are using PFC.
                                  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


                                    #18
                                    Re: Philips 37MF321D No power no LED

                                    Originally posted by budm View Post
                                    In this case, per SCH, the HI signal from main board will turn on Q7076, which will turn on the OPTO, which will turn on Q7063 which will supply the VCC voltage to the PFC Cotroller IC.
                                    Just an update on this television,
                                    Appling right around 3.3 volts to the stand buy pin causes the other 24 volt portion to come alive.
                                    Checking voltages going to the main board, I am loosing 16 volts to the 3A 1u101 fuse on the main board.
                                    I can trace the path of what should be the 16 volts to the 7003 L5972d switching regulator.
                                    It is easier to see in the photo but it has a very small pin hole in it.
                                    I will let you know what happens when I get the regulator. I am fortunate that it's a good number and Digi- Key has them.
                                    The two pictures Show the 24volt section that comes up with the 3.3 volts applied to the standby pin, and the 8SOIC regulator on the main board.
                                    Attached Files
                                    Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

                                    Comment


                                      #19
                                      Re: Philips 37MF321D No power no LED

                                      That is good the 24 PS is OK, and it sounds like you on the right path on the main board to find out you are not getting the PS_ON signal.
                                      You can read my basic guide if you want, it has the same idea but voltage value may be difference.
                                      Attached Files
                                      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


                                        #20
                                        Re: Philips 37MF321D No power no LED

                                        Originally posted by budm View Post
                                        You can read my basic guide if you want, it has the same idea but voltage value may be difference.
                                        Suggestion for budm.

                                        Create a new thread in the Troubleshooting TVs and Video Sources section and call it

                                        Basic LCD TV and Monitor trouble shooting guide by BM.pdf

                                        Put the pdf file in that thread and then provide a link to it for future people. That way, you don't have to upload the same pdf over and over again. And if you make revisions, you can tack it on to the same thread.
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                                        We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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                                        Comment

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