Samsung PN51D550 unable to power on

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  • hatechildren
    New Member
    • Feb 2013
    • 8
    • us

    #1

    Samsung PN51D550 unable to power on

    The TV turned off yesterday in the middle of watching it and now wont turn back on (no sound, no image, no response from remote/buttons). There is a 5 double blink LED light flashing where the power button is.

    Unplugging and plugging back in makes the 'on' click that repeats 5 times then stops. A green LED on one of the boards flashes in sync with this.
    I checked the caps and everything looks normal. My guess is a bad power supply, but TVs are far from my specialty. Any help would be appreciated!

    Here is an album with pictures and close ups.
    http://imgur.com/a/1NWxW
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Samsung PN51D550 unable to power on

    A very common failure on this set is the X-main:
    http://i.imgur.com/GImFfG3h.jpg

    Unplug all connectors from it, except the two brown ones going to the plasma panel.

    Then re-attempt power on.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • awyatt2
      Badcaps Veteran
      • Feb 2012
      • 407
      • america

      #3
      Re: Samsung PN51D550 unable to power on

      look on the heatsink rail you will find a pair of diodes they have three legs in a to220 case. the symbol is on the case dont remember if they are common anode or commom cathode and may be one of each. check it with ohm meter in diode setting. u may find the problem here. had three of them in three different samsungs same model, to fail and they have held up since i repaired them.i had a couple of old atx power supplys i borrowed the diodes from, tv is worth more than the powersupply.also you might want to run the caps with an esr meter to be sure. and there is a possibility this is not the problem but it is a weak area. one of them i am currently using now it is the 55d550. been using for over a year now. wife has it on most of the time.

      Comment

      • hatechildren
        New Member
        • Feb 2013
        • 8
        • us

        #4
        Re: Samsung PN51D550 unable to power on

        OK, I will try both of these when I get home and let you know how it goes. Thanks!

        Comment

        • hatechildren
          New Member
          • Feb 2013
          • 8
          • us

          #5
          Re: Samsung PN51D550 unable to power on

          It looks like I've misplaced my multimeter, so Ill have to wait on that test. But unplugging the xmain still has the same issues. Any other suggestions that wouldnt require a multimeter?

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: Samsung PN51D550 unable to power on

            Try with Y-main disconnected -- opposite board to X-main.
            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

            Comment

            • hatechildren
              New Member
              • Feb 2013
              • 8
              • us

              #7
              Re: Samsung PN51D550 unable to power on

              Originally posted by tom66
              Try with Y-main disconnected -- opposite board to X-main.
              Unplugged, and still has a clicking relay. I tried with only the main-logic and main-misc connected and it still clicks. With the main unplugged, no clicks.

              Comment

              • hatechildren
                New Member
                • Feb 2013
                • 8
                • us

                #8
                Re: Samsung PN51D550 unable to power on

                any other suggestions to try? or would anybody recommend which board to just replace and hope for the best?

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #9
                  Re: Samsung PN51D550 unable to power on

                  Here is one test:
                  - Unplug main board power connectors
                  - Disconnect main board to control board LVDS
                  - There is a four pin square connector on the board. Jumper pins 3-4 of this

                  Then power on set by plugging in... do you get test patterns.
                  Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                  For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                  Comment

                  • hatechildren
                    New Member
                    • Feb 2013
                    • 8
                    • us

                    #10
                    Re: Samsung PN51D550 unable to power on

                    Originally posted by tom66
                    Here is one test:
                    - Unplug main board power connectors
                    - Disconnect main board to control board LVDS
                    - There is a four pin square connector on the board. Jumper pins 3-4 of this

                    Then power on set by plugging in... do you get test patterns.
                    No test patterns. but the relay doesnt click right away (it does once after a few minutes) and the red LED on the power button is responding to the remote.

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #11
                      Re: Samsung PN51D550 unable to power on

                      Can you check the 5V supply on the control board -- is it steady?
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      • hatechildren
                        New Member
                        • Feb 2013
                        • 8
                        • us

                        #12
                        Re: Samsung PN51D550 unable to power on

                        Originally posted by tom66
                        Can you check the 5V supply on the control board -- is it steady?
                        The control board is this correct? http://i.imgur.com/oqc4rTvh.jpg
                        Assuming it is, its listed as 5.3v on the board, but im getting a reading of 5.9 when measuring from the power board itself while the 'control' board is unplugged. if its plugged in, im getting a reading of 5.9 breifly before dropping to 0 (this coincides with the relay clicking)

                        Comment

                        • tom66
                          EVs Rule
                          • Apr 2011
                          • 32560
                          • UK

                          #13
                          Re: Samsung PN51D550 unable to power on

                          Yes, that is the control board.
                          High 5.9V makes me suspicious of your multimeter battery -- can you swap it so we can be sure.
                          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                          Comment

                          • hatechildren
                            New Member
                            • Feb 2013
                            • 8
                            • us

                            #14
                            Re: Samsung PN51D550 unable to power on

                            Originally posted by tom66
                            Yes, that is the control board.
                            High 5.9V makes me suspicious of your multimeter battery -- can you swap it so we can be sure.
                            Ill have to wait until tomorrow until Im able to get another 9v battery. Anything I should try in the meantime?

                            Comment

                            • tadziuz
                              Member
                              • Feb 2013
                              • 10
                              • UK

                              #15
                              Re: Samsung PN51D550 unable to power on

                              Originally posted by awyatt2
                              look on the heatsink rail you will find a pair of diodes they have three legs in a to220 case. the symbol is on the case dont remember if they are common anode or commom cathode and may be one of each. check it with ohm meter in diode setting. u may find the problem here. had three of them in three different samsungs same model, to fail and they have held up since i repaired them.i had a couple of old atx power supplys i borrowed the diodes from, tv is worth more than the powersupply.also you might want to run the caps with an esr meter to be sure. and there is a possibility this is not the problem but it is a weak area. one of them i am currently using now it is the 55d550. been using for over a year now. wife has it on most of the time.
                              Did diodes from ATX PSU had the same markings? Just found one bad in my samsung tv and it is 30G124...

                              Comment

                              • awyatt2
                                Badcaps Veteran
                                • Feb 2012
                                • 407
                                • america

                                #16
                                Re: Samsung PN51D550 unable to power on

                                they were the same common anode or common cathode. samsung wanted 27.00 each so i used what i had and have been watching it for over a year now. my wife loves this tv. it is only off when she is at work or asleep.

                                Comment

                                • tadziuz
                                  Member
                                  • Feb 2013
                                  • 10
                                  • UK

                                  #17
                                  Re: Samsung PN51D550 unable to power on

                                  Originally posted by awyatt2
                                  they were the same common anode or common cathode. samsung wanted 27.00 each so i used what i had and have been watching it for over a year now. my wife loves this tv. it is only off when she is at work or asleep.
                                  In my case it seems to be a transistor and I can't find a datasheet for it. Found them on ebay but delivery from China gonna take ages Don't see any other options...

                                  Comment

                                  • vinceroger69
                                    Badcaps Legend
                                    • Mar 2012
                                    • 6714
                                    • uk

                                    #18
                                    Re: Samsung PN51D550 unable to power on

                                    Originally posted by tadziuz
                                    In my case it seems to be a transistor and I can't find a datasheet for it. Found them on ebay but delivery from China gonna take ages Don't see any other options...
                                    whats the part number on the item you are looking for?

                                    Comment

                                    • tw2005
                                      Badcaps Legend
                                      • Oct 2011
                                      • 6458
                                      • Australia

                                      #19
                                      Re: Samsung PN51D550 unable to power on

                                      I'm confused, are we talking about 30G124? is that the full number on the casing?
                                      If so and it is a transistor, Toshiba GT30G124 IGBT? N Channel, 430V ,Ic=30A Dc, 200A pulsed ,

                                      Comment

                                      • tadziuz
                                        Member
                                        • Feb 2013
                                        • 10
                                        • UK

                                        #20
                                        Re: Samsung PN51D550 unable to power on

                                        Originally posted by tw2005
                                        I'm confused, are we talking about 30G124? is that the full number on the casing?
                                        If so and it is a transistor, Toshiba GT30G124 IGBT? N Channel, 430V ,Ic=30A Dc, 200A pulsed ,
                                        This is the one I found on ebay:

                                        http://www.ebay.co.uk/itm/30G124-Man...item589aec8af7

                                        Anyway Im getting replacement X-Main board tomorrow and see what happens... Also found open fuse on Logic board but afer replacing it relay keeps clicking and front LED flashing even with disconentec x-main...
                                        Last edited by tadziuz; 02-21-2013, 11:02 AM.

                                        Comment

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