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BN44-00496B A5V only have 2.2V

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    BN44-00496B A5V only have 2.2V

    Hi everyone,

    I have this board, the output here only available 2.2V at the A5V circuit. Definitely this things doesn't powers up.

    B5V
    B13V
    measure 0

    LED connector at D1/DI+ give me constant 90V

    So far, I replace optocoupler as the anode/cathode doesn't give correct reading. Also replace the SSC 2S110 out of trying.

    Can anyone give me some suggestion?
    Also I need the schematic for this board too.

    I am familiar on laptop electronics, but not so much on TV powerboard.
    Attached Files
    Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

    #2
    Re: BN44-00496B A5V only have 2.2V

    What has caused the burning up on the circuit board ?
    Attached Files
    Willing to help but I'm no expert.

    Comment


      #3
      Re: BN44-00496B A5V only have 2.2V

      In the center of the burning up , there is a vertical resistance or maybe an inductor coil , it's not clear . Maybe it has changed of value or open ..

      Comment


        #4
        Re: BN44-00496B A5V only have 2.2V

        Originally posted by dick_barton View Post
        What has caused the burning up on the circuit board ?
        So far, tested the cap there value sufficient, underneath have a mosfet FDD7N25LZ. I removed and tested not shorted. Here I snap to photo at different angle, the bottom side. The topside burnt is exactly underneath this mosfet.
        Attached Files
        Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

        Comment


          #5
          Re: BN44-00496B A5V only have 2.2V

          You need to clean the solder balls from between the legs of the mosfet tidy up the solder joint of diode D9808 close by the mosfet

          Schematic attached may be similar to your power supply.
          Attached Files
          Last edited by dick_barton; 06-19-2017, 08:24 AM.
          Willing to help but I'm no expert.

          Comment


            #6
            Re: BN44-00496B A5V only have 2.2V

            Originally posted by jiroy View Post
            In the center of the burning up , there is a vertical resistance or maybe an inductor coil , it's not clear . Maybe it has changed of value or open ..
            Yes, it's an inductor if you referring to the vertical part. Measure 0.4ohm 0.0uH test frequency 200kHz, so not open. But 0.0uH? Anyway at this writing moment, I just test onboard, didn't remove it. And looking at the circuit, I assume this section is for LED strip power.

            Can clarify, the powering sequence of a tv powerboard?
            I am not very sure the cold side sequence. Is there a standardized sequence as in laptops?

            Sorry for the many questions asked, but trying to grasp the whole idea of a tv powerboard.
            Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

            Comment


              #7
              Re: BN44-00496B A5V only have 2.2V

              Normally there is one DC supply always available at the output which is the standby supply. This powers the mainboard and when the set is taken out of standby sends a signal to the power supply to switch on all the other DC supplies.

              If you disconnect the mainboard from the power supply what dc voltages do you have at the connector of the power supply?
              Last edited by dick_barton; 06-19-2017, 08:29 AM.
              Willing to help but I'm no expert.

              Comment


                #8
                Re: BN44-00496B A5V only have 2.2V

                Originally posted by dick_barton View Post
                You need to clean the solder balls from between the legs of the mosfet tidy up the solder joint of diode D9808 close by the mosfet

                Schematic attached may be similar to your power supply.
                Noted, thanks.
                Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                Comment


                  #9
                  Re: BN44-00496B A5V only have 2.2V

                  Originally posted by dick_barton View Post
                  Normally there is one DC supply always available at the output which is the standby supply. This powers the mainboard and when the set is taken out of standby sends a signal to the power supply to switch on all the other DC supplies.

                  If you disconnect the mainboard from the power supply what dc voltages do you have at the connector of the power supply?
                  Mainboard cable not connected to powerboard
                  Only have at CM801:
                  A5V - 2.2V
                  Power on/off - 0.729v
                  Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                  Comment


                    #10
                    Re: BN44-00496B A5V only have 2.2V

                    Have you lifted one end of each of the 4 diodes that rectify the 5V dc feeding the A5 output. I think they are probably the 4 larger diodes alongside each other. One of them may be leaky. Also test the capacitors connected to them on the A5 line.
                    Last edited by dick_barton; 06-19-2017, 08:48 AM.
                    Willing to help but I'm no expert.

                    Comment


                      #11
                      Re: BN44-00496B A5V only have 2.2V

                      After studying the schematic, I want to share this 2S110

                      Leg 2 - 1.28v seems normal
                      Leg 4 - 268v seems undervolt (schema shows 308v)
                      Leg 8 - 9.8V seems undervolt again as per schema 15v

                      Negative probe at Main filter cap
                      Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                      Comment


                        #12
                        Re: BN44-00496B A5V only have 2.2V

                        Originally posted by dick_barton View Post
                        Have you lifted one end of each of the 4 diodes that rectify the 5V dc feeding the A5 output. I think they are probably the 4 larger diodes alongside each other. One of them may be leaky. Also test the capacitors connected to them on the A5 line.
                        Thanks, will test those should be the 3 smaller diodes.

                        Now need to get my 6 year old kid to bed first, 11pm here. Will continue later if not too tired, or tomorrow. Working for the past 12 hours.
                        Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                        Comment


                          #13
                          Re: BN44-00496B A5V only have 2.2V

                          Check the resistors have not gone out of tolerance RM807, RM808 & RM809.
                          What DC voltage do you have between the two legs of capacitor CM8045
                          Willing to help but I'm no expert.

                          Comment


                            #14
                            Re: BN44-00496B A5V only have 2.2V

                            What DCV do you right between the two legs of each the main filter caps?
                            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


                              #15
                              Re: BN44-00496B A5V only have 2.2V

                              Main filter cap 315-317vdc. AC in now is 228v
                              Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                              Comment


                                #16
                                Re: BN44-00496B A5V only have 2.2V

                                Can I get hi-res clear straight shot of the bottom side of the board?
                                BTW, the A5V is only rated at 18mA as printed on the board so it will not take much to load that power supply down, but doubt that is is has that low of the current rating due to fact that the B5V is rated at 1.1A.
                                https://www.badcaps.net/forum/attach...2&d=1497851233

                                Never mind, I found good pictures at shojimmy.
                                http://www.shopjimmy.com/samsung-bn4...pply-unit.htm#
                                Pictures provided by shopjimmy.
                                Attached Files
                                Last edited by budm; 06-19-2017, 09:46 AM.
                                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


                                  #17
                                  Re: BN44-00496B A5V only have 2.2V

                                  Originally posted by jeremykum View Post
                                  Yes, it's an inductor if you referring to the vertical part. Measure 0.4ohm 0.0uH test frequency 200kHz, so not open. But 0.0uH? Anyway at this writing moment, I just test onboard, didn't remove it. And looking at the circuit, I assume this section is for LED strip power.

                                  Can clarify, the powering sequence of a tv powerboard?
                                  I am not very sure the cold side sequence. Is there a standardized sequence as in laptops?

                                  Sorry for the many questions asked, but trying to grasp the whole idea of a tv powerboard.
                                  It could be a resistance only , and after seeing the mosfet underneath , it is the mosfet causing heat anyway ..

                                  Comment


                                    #18
                                    Re: BN44-00496B A5V only have 2.2V

                                    What DCV do you have on the filter cap CM858 for the 13V power supply section?
                                    Also remove L9101 to see if the 5V will come up, if too hard then remove Q9101 instead.
                                    You did check Q9101 Source and Drain resistance to see if has low resistance, right?
                                    Last edited by budm; 06-19-2017, 09:35 AM.
                                    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


                                      #19
                                      Re: BN44-00496B A5V only have 2.2V

                                      Originally posted by dick_barton View Post
                                      Check the resistors have not gone out of tolerance RM807, RM808 & RM809.
                                      What DC voltage do you have between the two legs of capacitor CM8045
                                      I check those 3 smd resistor, 330k, as per printing on chip 3302. Should be fine.

                                      BTW the part code printing doesn't match as per the schematic provided. However the circuit I think should be almost identical, except some values of the ICs could be slightly different.
                                      Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                                      Comment


                                        #20
                                        Re: BN44-00496B A5V only have 2.2V

                                        Originally posted by budm View Post
                                        What DCV do you have on the filter cap CM858 for the 13V power supply section?
                                        Also remove L9101 to see if the 5V will come up, if too hard then remove Q9101 instead.
                                        You did check Q9101 Source and Drain resistance to see if has low resistance, right?
                                        On this board, this L shoud be L9801. Removed. Still 2.2V at A5V
                                        The filter cap for 13V register 0v. Circuit checked, not grounded.

                                        Q9101, should be the big N-Chan mosfet FDD7N25LZ, measured with DCA meter, seems working. Source and drain, one way register 11.2Mohm, the other way 0 (if continuity mode, no beeping).
                                        Attached Files
                                        Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                                        Comment

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