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Need help with Samsung LN40E550f7f

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    Need help with Samsung LN40E550f7f

    Hello all. Currently trying to fix my nieces tv. Has no video. She did her own research and did the flashlight test. then ordered a replacement inverter. I installed it, however it did not fix the problem. There are no swollen caps. I suspicion the power supply board, but I need a schematic or other assistance in testing. Yes, I have a multimeter and a usb oscilloscope however, I don't know how to use the oscilloscope yet. Have searched and searched for service manuals, schematics, etc. to no avail. The power supply board is a BN44004400B. Thanks!

    #2
    Re: Need help with Samsung LN40E550f7f

    pretty smart niece to figure that out it could be the inverter board. However for your board is a PSU repair kit at SJ available that fixes: The Samsung BN44-00440B Power Supply Component Repair Kit includes all necessary components to repair common failures on the Power Supply. Symptoms include will not turn on, no backlights, missing 5V standby or PFC.
    http://www.shopjimmy.com/samsung-bn4...repair-kit.htm

    Comment


      #3
      Re: Need help with Samsung LN40E550f7f

      So what Voltages do you have on the connector of the power supply board that goes to the main board when TV is in standby and when power switch is activated?
      You MUST report the pin name and follow by the Voltage reading for each pin so we can see if they are correct or not.
      We also need good clear the pictures of YOUR whole power supply board.
      Last edited by budm; 02-19-2018, 06:19 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


        #4
        Re: Need help with Samsung LN40E550f7f

        Exercise caution when testing power supply board, it can be deadly. there are legends like little maps on the power supply board that tell you what voltages to expect from the connector pins, put negative lead on ground like the chassis for example, also check those 2 fuses if you haven't, I check those fuses with tv off and unplugged. The voltages have to be checked with tv on or plugged in of course.
        Last edited by nomoresonys; 02-19-2018, 09:42 PM.

        Comment


          #5
          Re: Need help with Samsung LN40E550f7f

          Thank you for the input. I will consider that option if it turns out to be the problem.

          Comment


            #6
            Re: Need help with Samsung LN40E550f7f

            Voltages are as follows both on the power supply as well as the lead in to the logic board:
            Power supply:
            Pin 1=5.17
            2= 5.17
            4= 12.78
            5.=12.78
            6.=12.78
            7.=12.78
            At Logic Board= same

            Lead to inverter:

            pin 10= 12.07
            pin 2= 12.76

            At Inverter: Same

            Any not listed had value of 0.
            Attached Files

            Comment


              #7
              Re: Need help with Samsung LN40E550f7f

              Originally posted by nomoresonys View Post
              Exercise caution when testing power supply board, it can be deadly. there are legends like little maps on the power supply board that tell you what voltages to expect from the connector pins, put negative lead on ground like the chassis for example, also check those 2 fuses if you haven't, I check those fuses with tv off and unplugged. The voltages have to be checked with tv on or plugged in of course.
              Thank you for the warning. I actually have done a lot of computer work and 3 t.v.'s so far. I learned my lesson on things holding a charge years ago.
              I found the voltages on the board. - Not easy to read!

              Comment


                #8
                Re: Need help with Samsung LN40E550f7f

                If you do post voltages and pin numbers, you have to include the pin out name. Your pictures are way too small in order to see anything like that what we need. You need to upload high resolution pictures, so we can see the details.

                Comment


                  #9
                  Re: Need help with Samsung LN40E550f7f

                  1) No pin names to tell us what each pins are.
                  2) There are 14 pins on that power supply connector that goes to the main board but you only report 7 of them and without the pin names as requested then those reported numbers are just about meaningless.
                  3) Samsung BN44-00440B power supply board?
                  4) You need to follow the instructions.
                  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


                    #10
                    Re: Need help with Samsung LN40E550f7f

                    Originally posted by Kindred1 View Post
                    Thank you for the warning. I actually have done a lot of computer work and 3 t.v.'s so far. I learned my lesson on things holding a charge years ago.
                    I found the voltages on the board. - Not easy to read!
                    Cool, just a stock warning, cuz there's no way of telling a posters knowledge depth.

                    Comment


                      #11
                      Re: Need help with Samsung LN40E550f7f

                      Don't give up, what I do is just copy the legend/map on a piece of paper, pins and description, like bl-on etc, then just type it back in here with the voltage you got next to it.

                      Comment


                        #12
                        Re: Need help with Samsung LN40E550f7f

                        http://www.shopjimmy.com/samsung-bn4...upply-unit.htm is this your power board? you may have gotten a bad tcon board, hard to tell, I see shopjimmy has 1 for 10 bux. oops my bad you said inverter not tcon.
                        Last edited by nomoresonys; 02-20-2018, 08:54 PM.

                        Comment


                          #13
                          Re: Need help with Samsung LN40E550f7f

                          Does this tv have a metal back cover? if so are there any burn looking marks on it, like where the power board is etc. just worked on a sammy ln40c650, you can check my thread if you care to, but take your time, I double and triple checked everything before proceeding, you may have a whole different issue of course.

                          Comment


                            #14
                            Re: Need help with Samsung LN40E550f7f

                            Maybe start with those 2 big 450v filter capacitors, check m with black lead on negative side and red lead on positive side right on the legs, should get around 160 in standby and 380 volts while tv is on.

                            Comment


                              #15
                              Re: Need help with Samsung LN40E550f7f

                              I see now what you guys are talking about in regards to pin names. Will upload along with new pics.

                              Comment


                                #16
                                Re: Need help with Samsung LN40E550f7f

                                Originally posted by Kindred1 View Post
                                I see now what you guys are talking about in regards to pin names. Will upload along with new pics.
                                Cool, lets give it our best shot.

                                Comment


                                  #17
                                  Re: Need help with Samsung LN40E550f7f

                                  psb:
                                  1. B13V -13.1V

                                  2. DIM- 5V

                                  3. B13V-13.1V

                                  4. NC -0V

                                  5. B13V- 13.1V

                                  6.BLU_ON -0V

                                  7. B13V-13.1V

                                  8., 9., 10 GND- 0V

                                  11.B5V- 5.1V

                                  12 A5V - 5.1V

                                  13. B5V- 5.1V

                                  14. PS_ON- 3V
                                  Attached Files

                                  Comment


                                    #18
                                    Re: Need help with Samsung LN40E550f7f

                                    Here's a better one.
                                    Attached Files

                                    Comment


                                      #19
                                      Re: Need help with Samsung LN40E550f7f

                                      No scorch marks. 450v caps read 375v. Everyone is talking about standby mode; on this t.v. , when is off, the indicator light stays red and I have no readings. If I turn it on, it chimes, the light flashes and then goes off. After several minutes, it shuts off.

                                      Comment


                                        #20
                                        Re: Need help with Samsung LN40E550f7f

                                        Don't have a schematic, not sure if this one will do it, try unplug power supply board from main board, see if backlights go on.

                                        Comment

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