Need help with Samsung LN40E550f7f

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  • nomoresonys
    Badcaps Legend
    • Jan 2013
    • 12084
    • U.S.

    #61
    Re: Need help with Samsung LN40E550f7f

    Ok can you jumper blu_on a5 and and ps on together?

    Comment

    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12084
      • U.S.

      #62
      Re: Need help with Samsung LN40E550f7f

      Originally posted by Kindred1
      Jumped it. No backlight.
      You jumped it plugged in tv and turned on tv right?

      Comment

      • nomoresonys
        Badcaps Legend
        • Jan 2013
        • 12084
        • U.S.

        #63
        Re: Need help with Samsung LN40E550f7f

        no luck?

        Comment

        • nomoresonys
          Badcaps Legend
          • Jan 2013
          • 12084
          • U.S.

          #64
          Re: Need help with Samsung LN40E550f7f

          Starting to suspect your power supply board.

          Comment

          • nomoresonys
            Badcaps Legend
            • Jan 2013
            • 12084
            • U.S.

            #65
            Re: Need help with Samsung LN40E550f7f

            Theres some power supplies on ebay for 75 bucks, seems too high for a 40 inch tv tho. explains why theres so many lol. when you can find tvs on sale for 200 or so, thats like half the price of a whole tv.
            Last edited by nomoresonys; 02-24-2018, 08:40 AM.

            Comment

            • Kindred1
              Senior Member
              • Feb 2018
              • 55
              • USA

              #66
              Re: Need help with Samsung LN40E550f7f

              Originally posted by nomoresonys
              You jumped it plugged in tv and turned on tv right?
              Yes I did.

              Comment

              • Kindred1
                Senior Member
                • Feb 2018
                • 55
                • USA

                #67
                Re: Need help with Samsung LN40E550f7f

                Originally posted by nomoresonys
                Ok can you jumper blu_on a5 and and ps on together?
                Just to be clear, blu_on, A5 and PS_on?

                Comment

                • Kindred1
                  Senior Member
                  • Feb 2018
                  • 55
                  • USA

                  #68
                  Re: Need help with Samsung LN40E550f7f

                  Originally posted by nomoresonys
                  Theres some power supplies on ebay for 75 bucks, seems too high for a 40 inch tv tho. explains why theres so many lol. when you can find tvs on sale for 200 or so, thats like half the price of a whole tv.
                  I've found them cheaper. I just want to find out why the BLU_on is 0 volts.

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #69
                    Re: Need help with Samsung LN40E550f7f

                    The BLU_ON is from the main board.
                    >2.5VDC = Backlights circuit ON
                    <1VDC = Backlights circuit OFF.
                    So when you disconnect the cable from the power supply board to the main board and use the resistor between A5V and BL_ON is to simulate the ON signal.
                    Per your reported reading on the PS-ON pin and the DIM pin without the cable connected those signals are present due to pull-up resistor built into the power supply board, so that part of the power supply board is OK. If you look at the BL_ON pin right now with the resistor in place, you should then see >2.5V on that pin due to the resistor is being use to simulate the bl-on signal, it is present, right?
                    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

                    • Kindred1
                      Senior Member
                      • Feb 2018
                      • 55
                      • USA

                      #70
                      Re: Need help with Samsung LN40E550f7f

                      Hi Budm. - So you're saying with the jumper in place between a5 and blu-on, ( connected to the cable that connects to the main board) Check blu_ on for >2.5volts?

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #71
                        Re: Need help with Samsung LN40E550f7f

                        Originally posted by Kindred1
                        Hi Budm. - So you're saying with the jumper in place between a5 and blu-on, ( connected to the cable that connects to the main board) Check blu_ on for >2.5volts?
                        Yes.
                        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

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #72
                          Re: Need help with Samsung LN40E550f7f

                          BTW, that white fuse next to the main filter caps are OK, right?
                          That fuse provides 380VDC boosted Voltage to run the Inverter circuit.
                          I hope you do not have two problems:
                          1) Main board not sending BL-ON signal.
                          2) No backlights when forced on.
                          Attached Files
                          Last edited by budm; 02-24-2018, 07:22 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

                          • Kindred1
                            Senior Member
                            • Feb 2018
                            • 55
                            • USA

                            #73
                            Re: Need help with Samsung LN40E550f7f

                            I must not be checking the right spot. I put the lead on blu_on pin at the power supply and get 5.17. My meters lowest setting for ohms is 200. I'm going to get my toner that has continuity tester.

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #74
                              Re: Need help with Samsung LN40E550f7f

                              Originally posted by Kindred1
                              I must not be checking the right spot. I put the lead on blu_on pin at the power supply and get 5.17. My meters lowest setting for ohms is 200. I'm going to get my toner that has continuity tester.
                              Since you are not using the resistor on the the BL-ON pin thus it will show the same Voltage reading as A5V, the bottom line is that BL-ON pin is showing >2.5V which is more than enough to turn on the circuit.
                              Last edited by budm; 02-24-2018, 07:24 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

                              • Kindred1
                                Senior Member
                                • Feb 2018
                                • 55
                                • USA

                                #75
                                Re: Need help with Samsung LN40E550f7f

                                Originally posted by budm
                                BTW, that white fuse next to the main filter caps are OK, right?
                                That fuse provides 380VDC boosted Voltage to run the Inverter circuit.
                                I hope you do not have two problems:
                                1) Main board not sending BL-ON signal.
                                2) No backlights when forced on.
                                fuses are good

                                Comment

                                • Kindred1
                                  Senior Member
                                  • Feb 2018
                                  • 55
                                  • USA

                                  #76
                                  Re: Need help with Samsung LN40E550f7f

                                  Originally posted by budm
                                  Since you are not using the resistor on the the BL-ON pin thus it will show the same Voltage reading as A5V, the bottom line is that BL-ON pin is showing >2.5V which is more than enough to turn on the circuit.
                                  O.K. So, what's my next step?

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #77
                                    Re: Need help with Samsung LN40E550f7f

                                    Just to be sure with the test setup as it is right now, please verify that you do have about 380VDC between the two legs of the main filter cap (you can shcek on either one of them since they are connected in parallel).
                                    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

                                    • Kindred1
                                      Senior Member
                                      • Feb 2018
                                      • 55
                                      • USA

                                      #78
                                      Re: Need help with Samsung LN40E550f7f

                                      Originally posted by budm
                                      Just to be sure with the test setup as it is right now, please verify that you do have about 380VDC between the two legs of the main filter cap (you can shcek on either one of them since they are connected in parallel).
                                      Both reading 368v. With jumper still in place. Now I may have misunderstood directions early on. I reconnected power to main, but one end of jumper in the blu_ on lead in the plug. I do get proper voltage. Both ends. Sorry if I screwed up.

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #79
                                        Re: Need help with Samsung LN40E550f7f

                                        Originally posted by Kindred1
                                        Both reading 368v. With jumper still in place. Now I may have misunderstood directions early on. I reconnected power to main, but one end of jumper in the blu_ on lead in the plug. I do get proper voltage. Both ends. Sorry if I screwed up.
                                        "but one end of jumper in the blu_ on lead in the plug. I do get proper voltage. Both ends." I do not understand, so you have jumper install between BLU_ON pin and the A5V pin while the cable between the power supply and the main board is still connected?
                                        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

                                        • Kindred1
                                          Senior Member
                                          • Feb 2018
                                          • 55
                                          • USA

                                          #80
                                          Re: Need help with Samsung LN40E550f7f

                                          No. Forget the 'jumper'. What I meant was used a piece of wire to get get access to the pin ( in between plug housing and wire) because my meter leads are too big. The used a meter to get a reading off the wire. - When I mention misunderstanding directions, I was referring to when you first had me checking voltages off the board early in this thread.

                                          Comment

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