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Samsung LN40B500P3F - Won't turn on

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    Samsung LN40B500P3F - Won't turn on

    Hello all,

    I am new to the community and very new to electronic repair. However, I am very patient, a good listener and willing to learn.

    I have a Samsung LN40B500P3F that just powered off when I was in the middle of watching House of Cards Season 2. I opened it up and checked the fuses. The 250v 3.15 Fuse was blown when I tested it with my dmm. I went to Radio Shack just to try to put a new one. They only had a 125v 3.15 fuse that was clear, but the employee said it should work fine. I put it in and it immediately blew when I connected power (as expected). I read up on testing N channel MOSFETs using a dmm. I got the datasheet online after looking up the number (F22nm60n)- http://www.alldatasheet.com/datashee.../F11NM60N.html. Three of the N channel MOSFETs read 558 or 559 on the diode setting. Two of them appear to be faulty and set off the auditory alarm on my dmm. I assume this is part of the problem with the power supply/inverter board, but I don't know what else to test from here. I am fine with just buying a new board if, but would like some advice if there is another less expensive solution. I saw this repair kit on ShopJimmy, but I am not confident enough with my soldering skills yet- http://www.shopjimmy.com/samsung-bn4...repair-kit.htm. I also want to verify that it is indeed my power supply and not my main board. I assume it is with the FETs testing bad, but I am new to this whole repair bit and am looking for advice/help.

    I read on these two threads and performed the reccomended tests- https://www.badcaps.net/forum/showth...ng+LN40B500P3F - Same results: No readings when testing the 4 points recommended by budm at OHM mode at 200K. I have not done the light bulb test.
    I also read this thread, but I am not sure it applies to my problem-
    https://www.badcaps.net/forum/showth...LN40B500P3FXZA

    There were a few other threads that I read, but I figured I just needed to start a new one. Thanks for looking and helping.

    #2
    Re: Samsung LN40B500P3F - Won't turn on

    Blown fuse and MOSFETs that tested bad.
    Attached Files

    Comment


      #3
      Re: Samsung LN40B500P3F - Won't turn on

      I just checked the ShopJimmy website. Unfortunately, the part I need is out of stock. Any ideas where I can find a new power supply inverter board? Part # is Samsung BN44-00264A PCB, Power Supply.

      Comment


        #4
        Re: Samsung LN40B500P3F - Won't turn on

        might be worth bidding on this if its the correct one
        http://www.ebay.com/itm/BN44-00264A-...item4ad050bd81

        Comment


          #5
          Re: Samsung LN40B500P3F - Won't turn on

          I just looked @ Shopjimmy and found these:

          http://www.shopjimmy.com/samsung-bn4...t-inverter.htm

          Looks like there are a couple of other power supplies that will work.

          Comment


            #6
            Re: Samsung LN40B500P3F - Won't turn on

            Thanks guys. My wife is on me about getting this repaired fairly quick. She is a stay at home mom and doesn't like not having any TV. I don't know how I missed the other options at ShopJimmy. I will probably just order once of the other boards it says are compatible. I would love to wait to see what the one on ebay goes for, but I doubt my wife would let me hold off that long. Lol.

            Comment


              #7
              Re: Samsung LN40B500P3F - Won't turn on

              Well, nevermind. It says all the alternatives are also out of stock.

              Comment


                #8
                Re: Samsung LN40B500P3F - Won't turn on

                Something is not right with the MOSFETs that are making the meter beep. Its a hot side of the power supply dead short. I'd advise taking them out of circuit and retest. Also while they're out of circuit check for any diodes That might be shorted. you would be surprised how much of a simple repair this could be.
                Did I leave the soldering iron on?

                Comment


                  #9
                  Re: Samsung LN40B500P3F - Won't turn on

                  theres not much in the repair kits for this fault
                  http://www.ebay.com/itm/2x-FQPF9N50-...item3f2e14f2f5

                  Comment


                    #10
                    Re: Samsung LN40B500P3F - Won't turn on

                    I tested the diodes. All tested fine. Any idea where I can get FETs? Would radioshack have an equivalent to FQPF9N50? I saw a few from china on ebay, but was hoping for one a little more local. http://www.ebay.com/itm/2pieces-FQPF...item27bdccf3c4

                    Comment


                      #11
                      Re: Samsung LN40B500P3F - Won't turn on

                      Just noticed this is the number on my FET - F11nm60n

                      Comment


                        #12
                        Re: Samsung LN40B500P3F - Won't turn on

                        Schematic.
                        http://www.shopjimmy.com/samsung-bn4...wer-supply.htm
                        It looks like B can be used, you can contact SJ to verify.
                        Attached Files
                        Last edited by budm; 02-20-2014, 05:40 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


                          #13
                          Re: Samsung LN40B500P3F - Won't turn on

                          Thanks everyone. I was able to order the board through ShopJimmy on Amazon. I might use the other one as a guinea pig and see if I can problem solve it.

                          Comment


                            #14
                            Re: Samsung LN40B500P3F - Won't turn on

                            Can you tell me if his AMAZON price is cheaper than his web site price, free shipping? I search BN44-00264A and do not see SJ comes up.
                            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: Samsung LN40B500P3F - Won't turn on

                              Digikey has the FETs you need.

                              http://www.digikey.com/product-detai...FFS-ND/1954601

                              Comment


                                #16
                                Re: Samsung LN40B500P3F - Won't turn on

                                Thanks for the help. I was able to fix the TV with the new board. Yippee! I am still going to try to fix the other board.

                                budm, the Amazon price was about the same. I paid $70 through Amazon. I think buying from ShopJimmy directly was $68 roughly after shipping. Here is the link to the shopjimmy storefront on Amazon- http://www.amazon.com/gp/browse.html...=AJSCKUS9BOH8E

                                Comment


                                  #17
                                  Re: Samsung LN40B500P3F - Won't turn on

                                  Greetings, I have the same issue on my LN40B650 which has the same power supply board (BN044-0264A). I'm also a DIY kind of guy but my knowledge in electronics are kinda limited (solder skills good, Already repaired a couple of PS with bad caps but that it!). So I'm looking for help here.

                                  Out of the blue the stand by LED disapeared and the tv isn't swithing on anymore. I opened it and figured out that the 2nd fuse FM802S on the diagram was dead. I bought some more (exam same reference from Little fuse 250V/3.15A slow blow fuse) and upon installing it and connecting the TV to the power outlet it instantly blows, dit the test twice, with and without the cable going from the SPS to the Mainboard connected.

                                  So definitelly another component should be dead. The caps should be ok, they look good at least, no leakeage spotted.

                                  Any idea to what test I could do with a DMM to pinpoint the bad guy? On hte cold section, I pretty much get 0V anywhere as the fuse is blowing and cuts whatever is after it.

                                  I can post whatever photo needed!

                                  Thanks
                                  Attached Files

                                  Comment


                                    #18
                                    Re: Samsung LN40B500P3F - Won't turn on

                                    Check resistance on the two legs of the snubber capacitors CI890 and CI891 to see if it shows very low resistance.
                                    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: Samsung LN40B500P3F - Won't turn on

                                      Originally posted by budm View Post
                                      Check resistance on the two legs of the snubber capacitors CI890 and CI891 to see if it shows very low resistance.
                                      budm, than you for the quick reply. Here are the readings:

                                      CI890 = 00.6 ohms
                                      CI891 = 00.6 ohms

                                      They are shorted. I remember tryng the voltage of the 2 big caps (CP816 and CP817) while connected and they were around 200V If I remember correctly.

                                      Comment


                                        #20
                                        Re: Samsung LN40B500P3F - Won't turn on

                                        OK, remove both caps and check the resistances of the caps again off the board. It is either shorted caps or shorted power MOSFETs.
                                        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

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