Need help with Samsung LN40E550f7f

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  • Kindred1
    Senior Member
    • Feb 2018
    • 55
    • USA

    #121
    Re: Need help with Samsung LN40E550f7f

    Originally posted by budm
    Is the ON = 169.2V reading with PS-ON present? If PS-ON present then we have problem with the PFC circuit. But I thought you have 365V on the fuse next to the filter cap before in the earlier thread, that must have been an error then.
    O.K. What I have is : 164.5 vdc with power on. 168.3 vdc on standby.

    361 vac with power on, 370 vac on standby.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #122
      Re: Need help with Samsung LN40E550f7f

      The readings in AC mode are just error of you meter.
      Try measuring your car battery in AC Volt mode to see what you get, it will show high reading. Your meter probably has simple half-wave rectifier in the AC input circuit of the meter feeding resistor networks for the meter scale.
      Any way, you will need to fix the PFC circuit at this point.
      Real AC Voltage of over 300VAC on that electrolytics cap would have blown the cap by now.
      https://www.badcaps.net/forum/attach...6&d=1519521712
      Check the RESISTANCE of the PFC diodes in both directions to see how many Ohms they will show.
      Last edited by budm; 02-27-2018, 09:59 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

        #123
        Re: Need help with Samsung LN40E550f7f

        Originally posted by budm
        The readings in AC mode are just error of you meter.
        Try measuring your car battery in AC mode to see what you get.
        Any way, you will need to fix the PFC circuit at this point.
        Real AC Voltage of over 300VAC on that electrolytics cap would have blown the cap by now.
        https://www.badcaps.net/forum/attach...6&d=1519521712
        Check the RESISTANCE of the PFC diodes in both directions to see how many Ohms they will show.
        Yes. Hence my comment to you regarding me misunderstanding and screwing up. Apparently headaches/neckaches effect brain function. Anyway, I will do that first thing tomorrow and post my results. Thanks!

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #124
          Re: Need help with Samsung LN40E550f7f

          At this point it is safe to say that you do have problem in that power supply/inverter driver board, you have all the correct command Voltages and other low switched Voltages but do not have the boosted Voltage to run the inverter driver circuits, we are getting there.
          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

          • nomoresonys
            Badcaps Legend
            • Jan 2013
            • 12085
            • U.S.

            #125
            Re: Need help with Samsung LN40E550f7f

            http://en-us.fluke.com/training/trai...ultimeter.html I believe you said your meter wasnt working in diode mode, this shows how to check diode in ohm mode, if you get ol in both directions try setting meter at 2000 ohm, often you get inaccurate measurement results when left in circuit. Diode should read ol in one direction, reverse meter leads and should get a reading.
            Last edited by nomoresonys; 02-28-2018, 06:04 AM.

            Comment

            • Kindred1
              Senior Member
              • Feb 2018
              • 55
              • USA

              #126
              Re: Need help with Samsung LN40E550f7f

              Ok guys. I got my meter working properly. SO, in diode mode DP810 and DP802 both read .6v in diode mode - OL in reverse as it should I believe. However in Ohm mode I get OL both directions no matter what setting it's at. I have tested other circuits to verify ohm mode is working.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #127
                Re: Need help with Samsung LN40E550f7f

                OK, then we need to look deeper in the PFC circuit section, need to get the P/N of the PFC Controller IC so we can look up the spec sheet to locate the VCC pin to see if it is getting the switched VCC for the PFC IC to run or not.
                PFC IC has designator as ICP801.

                Repair kit:http://www.shopjimmy.com/samsung-bn4...repair-kit.htm
                Last edited by budm; 02-28-2018, 01:57 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

                  #128
                  Re: Need help with Samsung LN40E550f7f

                  Ok, I found it. - It appears to have a little corrosion/heat damage on the top. ( no scorching on or around.) All I can make out is as follows.
                  B7E
                  AN
                  7930B
                  Attached Files

                  Comment

                  • nomoresonys
                    Badcaps Legend
                    • Jan 2013
                    • 12085
                    • U.S.

                    #129
                    Re: Need help with Samsung LN40E550f7f

                    Originally posted by Kindred1
                    Ok guys. I got my meter working properly. SO, in diode mode DP810 and DP802 both read .6v in diode mode - OL in reverse as it should I believe. However in Ohm mode I get OL both directions no matter what setting it's at. I have tested other circuits to verify ohm mode is working.
                    Sometimes you will get an error reading when testing in circuit.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #130
                      Re: Need help with Samsung LN40E550f7f

                      FAN7930B
                      https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
                      Pin 8 is VCC, Pin 6 is GND which is connected to circuit GND (negative leg of the main filter cap) of the hot side, so be real careful since you are making measurement in the HOT DEADLY side of the circuit; I suggest you to at the least plug the TV into the GFCI outlet to protect yourself.
                      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

                      • nomoresonys
                        Badcaps Legend
                        • Jan 2013
                        • 12085
                        • U.S.

                        #131
                        Re: Need help with Samsung LN40E550f7f

                        https://www.digikey.com/products/en?...G&pkeyword=&v=
                        Is this it?

                        Comment

                        • Kindred1
                          Senior Member
                          • Feb 2018
                          • 55
                          • USA

                          #132
                          Re: Need help with Samsung LN40E550f7f

                          Originally posted by budm
                          FAN7930B
                          https://cdn.badcaps-static.com/pdfs/...0db2152410.pdf
                          Pin 8 is VCC, Pin 6 is GND which is connected to circuit GND (negative leg of the main filter cap) of the hot side, so be real careful since you are making measurement in the HOT DEADLY side of the circuit; I suggest you to at the least plug the TV into the GFCI outlet to protect yourself.
                          I get 34.7vac

                          Comment

                          • Kindred1
                            Senior Member
                            • Feb 2018
                            • 55
                            • USA

                            #133
                            Re: Need help with Samsung LN40E550f7f

                            Originally posted by nomoresonys
                            My antivirus blocks that page.

                            Comment

                            • nomoresonys
                              Badcaps Legend
                              • Jan 2013
                              • 12085
                              • U.S.

                              #134
                              Re: Need help with Samsung LN40E550f7f

                              Originally posted by Kindred1
                              My antivirus blocks that page.
                              lol, thats digikey theyre known worlwide, definitely not a nefarious site.

                              Comment

                              • Kindred1
                                Senior Member
                                • Feb 2018
                                • 55
                                • USA

                                #135
                                Re: Need help with Samsung LN40E550f7f

                                Originally posted by nomoresonys
                                lol, thats digikey theyre known worlwide, definitely not a nefarious site.
                                I think it's just their certificate. Heading there now.

                                Comment

                                • Kindred1
                                  Senior Member
                                  • Feb 2018
                                  • 55
                                  • USA

                                  #136
                                  Re: Need help with Samsung LN40E550f7f

                                  the 4th one is.

                                  Comment

                                  • nomoresonys
                                    Badcaps Legend
                                    • Jan 2013
                                    • 12085
                                    • U.S.

                                    #137
                                    Re: Need help with Samsung LN40E550f7f

                                    You could exclude them in your antivirus, as in white list, lets the antivirus know that this site is ok.

                                    Comment

                                    • nomoresonys
                                      Badcaps Legend
                                      • Jan 2013
                                      • 12085
                                      • U.S.

                                      #138
                                      Re: Need help with Samsung LN40E550f7f

                                      Originally posted by Kindred1
                                      the 4th one is.
                                      Ok, make sure, I think digikey has more reasonable shipping costs than mouser.

                                      Comment

                                      • nomoresonys
                                        Badcaps Legend
                                        • Jan 2013
                                        • 12085
                                        • U.S.

                                        #139
                                        Re: Need help with Samsung LN40E550f7f

                                        Will 5 or 6 work, not sure but I think 4 says minimum purchase is 2500, you could call and ask tho.

                                        Comment

                                        • Kindred1
                                          Senior Member
                                          • Feb 2018
                                          • 55
                                          • USA

                                          #140
                                          Re: Need help with Samsung LN40E550f7f

                                          All the specs seem the same except for the packaging type. I don't know anything about said components except what I'm learning.

                                          Comment

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