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    Samsung UN55EH6000F Power issue

    I got in a Samsung UN55EH6000F with no power and blown fuse on the board (BN44-00499A) I found 3 bad mosfets and a blown resistor circled in the pictures. Now just putting power to the board and checking voltages I get what I need 13v then goes off and on over and over. I connected to TV and TV powers on with sound then off over and over again. I did not include pics of the TV since it is in the power board. So what would cause it to power on and off repeatedly? ?
    Attached Files

    #2
    Re: Samsung UN55EH6000F Power issue

    Check all the diodes and touch up any solder joints that look odd.

    Comment


      #3
      Re: Samsung UN55EH6000F Power issue

      Yep, went through all that before posting.

      Comment


        #4
        Re: Samsung UN55EH6000F Power issue

        That looks like a gate drive resistor, I would check the zener diodes and the other resistors in that drive circuit.
        One of the components you have circled is the standby ic, was it replaced as well?
        Last edited by R_J; 01-20-2022, 08:00 PM.

        Comment


          #5
          Re: Samsung UN55EH6000F Power issue

          Originally posted by CraigR View Post
          Yep, went through all that before posting.
          At least a few still look cracked to me.

          Comment


            #6
            Re: Samsung UN55EH6000F Power issue

            Originally posted by R_J View Post
            That looks like a gate drive resistor, I would check the zener diodes and the other resistors in that drive circuit.
            One of the components you have circled is the standby ic, was it replaced as well?
            Yes, it was replaced also.

            Comment


              #7
              Re: Samsung UN55EH6000F Power issue

              I found this mosfet (2 legs gone now) with nothing going threw it compared to other one with same number. Anybody know how I can get a good number to get another? WR N7 not coming up with anything on google.
              Attached Files

              Comment


                #8
                Re: Samsung UN55EH6000F Power issue

                What is the board location?
                Last edited by R_J; 01-26-2022, 04:06 PM.

                Comment


                  #9
                  Re: Samsung UN55EH6000F Power issue

                  Looks to be an NPN. If it is sot-23
                  WR 2PD602R Si-npn GP, Sw, 60V, 500mA, 250mW, B=120..240, >160MHz SOT-23

                  If you have a component tester, just remove the other one and check it.
                  Last edited by dskall; 01-26-2022, 03:39 PM.
                  I assume no responsibility for any stupid suggestions I might post.

                  Comment


                    #10
                    Re: Samsung UN55EH6000F Power issue

                    .

                    Comment


                      #11
                      Re: Samsung UN55EH6000F Power issue

                      Originally posted by R_J View Post
                      Might be 2SK322WR What is the board location?
                      ZDL802 so must be zener diode and not a mosfet? the N made me think N channel?

                      Comment


                        #12
                        Re: Samsung UN55EH6000F Power issue

                        Bzx84c24-au
                        Attached Files

                        Comment


                          #13
                          Re: Samsung UN55EH6000F Power issue

                          That looks correct, let me guess, they are in the gate circuit.

                          Comment


                            #14
                            Re: Samsung UN55EH6000F Power issue

                            in the gate circuit
                            Attached Files

                            Comment


                              #15
                              Re: Samsung UN55EH6000F Power issue

                              Yep. Thanks for the number! I will order some up and get back with how it goes.

                              Comment


                                #16
                                Re: Samsung UN55EH6000F Power issue

                                UPDATE: Same thing. 13v then zero just keeps doing it over and over. I was looking it all over again and see a tiny crack in the big green thermister wtr15d050 but I get 8.3 ohms cold so not sure if the crack means damage or not?
                                Last edited by CraigR; 02-03-2022, 10:57 AM.

                                Comment


                                  #17
                                  Re: Samsung UN55EH6000F Power issue

                                  What about the A5V is it changing as well?

                                  Comment


                                    #18
                                    Re: Samsung UN55EH6000F Power issue

                                    Originally posted by R_J View Post
                                    What about the A5V is it changing as well?
                                    Yes it is.

                                    Comment


                                      #19
                                      Re: Samsung UN55EH6000F Power issue

                                      Originally posted by CraigR View Post
                                      Yes it is.
                                      The first thing I would try is to connect the PS_ON/OFF pin to ground, this should place the power supply in standby mode, then you can see if the standby voltage A5V is stable.
                                      CNM803 pin 14 is PS_ON/OFF
                                      Last edited by R_J; 02-03-2022, 01:42 PM.

                                      Comment


                                        #20
                                        Re: Samsung UN55EH6000F Power issue

                                        Originally posted by R_J View Post
                                        The first thing I would try is to connect the PS_ON/OFF pin to ground, this should place the power supply in standby mode, then you can see if the standby voltage A5V is stable.
                                        CNM803 pin 14 is PS_ON/OFF
                                        Zero volts 5 nor 13 when when PS_ON/OFF jumped to ground.

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