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    UN46EH6000 does not turn on and no LED

    Just Picked up this UN46EH6000 TV that has a BN44-00498A Power supply, nothing happens when power button is pressed moments later a slight clicking sound can be heard. Back lights will not turn on when unplugging the connector to the other board. I seem to have all the voltages on the hot side. At CM803 I only have 5V on pin 12 and 3v on pin PS_on (other board unplugged). all non surface mount diodes are good, capacitors CM851, C9110, CS855, CM875, CM858 removed and tested good. Someone have an Idea of what could be the cause, do I need to 'activate' PS_on to see other voltages? Is PS_on looking for a ground? or 5v to turn on rest of the board voltages.
    Attached is the schematic to help figure it out, the number is slightly different but seems to be the same from what I can see and is easier to read.
    Attached Files

    #2
    Re: UN46EH6000 does not turn on and no LED

    Lets see good clear pictures of the hwole top and bottom side of the power supply board.
    Since the PS-on is present, then you sjould have about 380 ~ 400V DC between the two legs of the main filter cap in the hot side.
    BTW, your board is BN44-00498A, not BN44-00473A, correct? The schematic you provided is for BN44-00473A.
    We also need to know the Voltages of all other pin of the power supply connector that goes to the main board, measure them without having it connected to the main board, make sure to put down pin names and follow by the voltage reading for each pin so we can easily see what are missing.
    This is your board, right?
    https://www.shopjimmy.com/samsung-bn...pply-board.htm
    Last edited by budm; 05-24-2019, 08:09 PM.
    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: UN46EH6000 does not turn on and no LED

      I will post later today clear pictures of both sides of the board once I reinstall the capacitors I tested, it is the board you show in the link with a slight difference, there is no capacitor and jumper next to CAP CM851. I attached the -00473A as a reference only since it is a clearer image than what I found for the -00498A and seems to be the same. I do Have 390V at the Main Capacitor. below are the pin idents and what I tested.
      1 B13V Tested 0v
      2 PWM_DIM Tested 0v
      3 B13V Tested 0v
      4 B13V Tested 0v
      5 Vamp Tested 0v
      6 BLU_on/Off Tested 0v
      7 Vamp Tested 0v
      8 GND
      9 GND
      10 GND
      11 B5V Tested 0v
      12 A5V Tested 0v
      13 B5V tested 5V
      14 Power on/Off Tested 3V

      Comment


        #4
        Re: UN46EH6000 does not turn on and no LED

        BLU-ON equals 0, which means no backlights, try using a 1k resistor and jump blu-on pin with b5 standby, see if backlight come on and stay on as long as it's jumpered.

        Comment


          #5
          Re: UN46EH6000 does not turn on and no LED

          Originally posted by Plane Nuts View Post
          Back lights will not turn on when unplugging the connector to the other board..
          Need to confirm the backlights are good plus there could be an issue with power supply.

          Seeing LED failures in E, F and H model years requiring full replacement of all strips due to the high number of LEDs bad. Unlike LG, power supply doesn't shut down the backlight on error and there could be damage to the power supply in some cases as well.

          https://www.badcaps.net/forum/showth...ht=UN46EH5300F
          Last edited by neilc6; 05-25-2019, 12:34 PM.

          Comment


            #6
            Re: UN46EH6000 does not turn on and no LED

            Originally posted by Plane Nuts View Post
            I will post later today clear pictures of both sides of the board once I reinstall the capacitors I tested, it is the board you show in the link with a slight difference, there is no capacitor and jumper next to CAP CM851. I attached the -00473A as a reference only since it is a clearer image than what I found for the -00498A and seems to be the same. I do Have 390V at the Main Capacitor. below are the pin idents and what I tested.
            1 B13V Tested 0v
            2 PWM_DIM Tested 0v
            3 B13V Tested 0v
            4 B13V Tested 0v
            5 Vamp Tested 0v
            6 BLU_on/Off Tested 0v
            7 Vamp Tested 0v
            8 GND
            9 GND
            10 GND
            11 B5V Tested 0v
            12 A5V Tested 0v
            13 B5V tested 5V

            14 Power on/Off Tested 3V
            It looks like listing error, I am sure you do have A5V.
            So PFC Boosted Voltage is working, at this point you must fix the switched B5V and B13V first.
            I need to see the pictures of your whole board, top and bottom side.
            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: UN46EH6000 does not turn on and no LED

              Attached is the pictures of the board, and the schematic matching the P/N of the Board. Note that the red wires goes to a fuse holder since I don't have a solder on fuse at this time.

              Also note that ALL test are done with circuit board and Back lights disconnected. I am on a business trip and only brought that board with me to pass the time.

              nomoresonys since back light is not connected I assume that if I jump the pins I would expect to see voltage somewhere in the back light connector?

              At the moment I have the following in CNL802 (backlight connector)
              9 (D1-) .7v
              8 (D1-) .7v
              7 NC
              6 (S-) 0v
              5 NC
              4 (S+) 0v
              3 NC
              2 (D1+) 0v
              1 (D1+) 0v

              And good catch Budm the following cponfirms what I have:
              11 B5V tested 0V
              12 A5V tested 5V
              13 B5V tested 0V
              14 Power O/N/Off tested 3V

              I have also poked around the board and have the following:
              CS 805 14.7V Across Poles
              CS811 12V Across Poles
              DS853 5V Across Poles
              DM855 0V Across Poles and to ground
              C9110 0V Across Poles and to ground
              D9102 0V Across Poles and to ground
              CP8145 395V Across Poles 395v/0v to (-) of rectifier BD801
              DP808 257V Across Poles 148v/395v to (-) of rectifier BD801
              DP803 254V Across Poles 148v/395v to (-) of rectifier BD801
              DP802 2V Across Poles 148v/148v to (-) of rectifier BD801
              DS804 8V/12V Across Poles 1.8/12v to (-) of rectifier BD801
              DS806 9V/15V Across Poles 1.8/14v to (-) of rectifier BD801
              Attached Files

              Comment


                #8
                Re: UN46EH6000 does not turn on and no LED

                What is the P/N of that SMPS IC right next to the fuse FP802S? You need to find out if it is getting VCC Vaoltage for it to run or not.
                That is the section you need to check, that section is for the switched B5V, B13V, and power supply for feeding the boost converter for the LED driver circuit.
                No need to poke around the PFC section, the section with part designator with P, I.E. DP8O3, that diode belongs to the PFC section , that is why it has P in the designator. You need to be able to section out the board and know what each section of the board is for, we do not want poke around and may have accident and damage the working section, just concentrate in the B5V, B13V as suggested, since the diagram does not match your board so the result you get may not be correct. Designator with S is for the standby section.
                Last edited by budm; 05-25-2019, 04:09 PM.
                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: UN46EH6000 does not turn on and no LED

                  Maybe check the diodes in diode mode if any read off lift one leg and check again.

                  Comment


                    #10
                    Re: UN46EH6000 does not turn on and no LED

                    Originally posted by budm View Post
                    What is the P/N of that SMPS IC right next to the fuse FP802S? You need to find out if it is getting VCC Vaoltage for it to run or not.
                    That is the section you need to check, that section is for the switched B5V, B13V, and power supply for feeding the boost converter for the LED driver circuit.
                    No need to poke around the PFC section, the section with part designator with P, I.E. DP8O3, that diode belongs to the PFC section , that is why it has P in the designator. You need to be able to section out the board and know what each section of the board is for, we do not want poke around and may have accident and damage the working section, just concentrate in the B5V, B13V as suggested, since the diagram does not match your board so the result you get may not be correct. Designator with S is for the standby section.
                    thank-you budm for the guidance
                    See attached picture, is this the IC you are talking about? HS2 with the White plastic piece on top? the number is SFR1700XC.
                    Interestingly on the board that chip is identified as HS2 but in the schematics it is HS3 (confirmed by P/N)

                    for nomoresonys, all the diodes that are on the top side of the board tested good.
                    Attached Files
                    Last edited by Plane Nuts; 05-25-2019, 05:29 PM. Reason: HS2 on board is HS3 on schematic

                    Comment


                      #11
                      Re: UN46EH6000 does not turn on and no LED

                      HS = Heat sink, the ic location number is under the silicone, Check if you have VCC_IC_P going to the ic, Checking on the bottom is easy but if checking from the top, try and get to CM812 positive leg (in front of ic in silicone)
                      Last edited by R_J; 05-25-2019, 06:04 PM.

                      Comment


                        #12
                        Re: UN46EH6000 does not turn on and no LED

                        Originally posted by R_J View Post
                        HS = Heat sink, the ic location number is under the silicone, Check if you have VCC_IC_P going to the ic, Checking on the bottom is easy but if checking from the top, try and get to CM812 positive leg (in front of ic in silicone)
                        Here is what I get at IC between (-) of rectifier BD801S and the pin:
                        1 (VDl) 394v
                        2 (AR) .1v
                        3 (RT).1v
                        4 (CS).1v
                        5 (SG).1v
                        6 (PG).1v
                        7 (Lvcc)14v
                        8 (Hvcc)394v
                        9 (Vctr)394v

                        Between these pins and Lug1 (P-GND):
                        1 (VDl) 1v
                        2 (AR) .1v
                        3 (RT).1v
                        4 (CS).1v
                        5 (SG).1v
                        6 (PG).1v
                        7 (Lvcc).12v
                        8 (Hvcc).7v
                        9 (Vctr).7v

                        Comment


                          #13
                          Re: UN46EH6000 does not turn on and no LED

                          I think your ic is bad, Check the internal fets, I think the top one could be shorted (check the resitance between Vdl, Vctr and Vctr and PG). Check RM807 (0.2Ω) if it is open It is very likely the ic is bad.
                          They label the pins a bit different as there is no pin #8, so:
                          8 (Hvcc)394v = pin #9
                          9 (Vctr)394v = pin #10
                          Attached Files
                          Last edited by R_J; 05-26-2019, 09:33 AM.

                          Comment


                            #14
                            Re: UN46EH6000 does not turn on and no LED

                            Originally posted by R_J View Post
                            I think your ic is bad, Check the internal fets, I think the top one could be shorted (check the resitance between Vdl, Vctr and Vctr and PG). Check RM807 (0.2Ω) if it is open It is very likely the ic is bad.
                            They label the pins a bit different as there is no pin #8, so:
                            8 (Hvcc)394v = pin #9
                            9 (Vctr)394v = pin #10
                            R_J I get the following:

                            between Vdl and Vctr: 273/250 ohms
                            between Vctr and Pg: 1.3 Mohms
                            RM807 I get .4 ohms (still in place)

                            Far from being a pro at it, I would expect them to have to same values and what should I expect for a normal value?

                            Comment


                              #15
                              Re: UN46EH6000 does not turn on and no LED

                              The internal fets should measure open (Drain - Source) 250Ω is very low but not a short, Unless CM813 is bad? Maybe remove the cap and check it's resistance and check the ic's resistance Vdl~Vctr again
                              The resistor is good, and you were getting Lvcc to turn the ic on which is good.
                              Last edited by R_J; 05-26-2019, 10:07 AM.

                              Comment


                                #16
                                Re: UN46EH6000 does not turn on and no LED

                                Originally posted by R_J View Post
                                The internal fets should measure open (Drain - Source) 250Ω is very low but not a short, Unless CM813 is bad? Maybe remove the cap and check it's resistance and check the ic's resistance Vdl~Vctr again
                                The resistor is good, and you were getting Lvcc to turn the ic on which is good.
                                Removed CM813 and reads .0224 uF
                                you say to measure resistance of the cap I assume you mean capacitance? if it actualy is resistance, it is open.

                                same values for Vdl to Vctr 270 ohm one way and 247 ohm the other way with the cap out.

                                Comment


                                  #17
                                  Re: UN46EH6000 does not turn on and no LED

                                  I did mean resistance just to see if the cap was causing the low resistance, but the cap seems to be ok and the it looks like the internal fet is near shorted.

                                  Comment


                                    #18
                                    Re: UN46EH6000 does not turn on and no LED

                                    Originally posted by R_J View Post
                                    I did mean resistance just to see if the cap was causing the low resistance, but the cap seems to be ok and the it looks like the internal fet is near shorted.
                                    Without understanding the inner workings of the IC and the effects of the near short, is that enough to prevent getting the B5V and B13V voltages?

                                    Comment


                                      #19
                                      Re: UN46EH6000 does not turn on and no LED

                                      That is the ic that drives the transformer that produces the B5v and B13 volts. Sometimes they will use a driver ic and two seperate fets, in this case they are all in the same ic.
                                      The fets are used to switch the pfc voltage across the primary at a high frequency, this induces the current in the seconday winding providing the voltages
                                      Last edited by R_J; 05-26-2019, 12:55 PM.

                                      Comment


                                        #20
                                        Re: UN46EH6000 does not turn on and no LED

                                        So even though I am getting the 375 V to the transformer. the IC is basically not switching as it should to 'create AC power' to induce the voltage on the other side of the transformer.

                                        Comment

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