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42pfl3606h/12 Phillips tv powersupply/backlight problem

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    42pfl3606h/12 Phillips tv powersupply/backlight problem

    Hi guys
    I'm looking for some help fixing a problem with my TV and and found myself on this great site. I've done a lot of reading on here and thought I had found the solution but haven't so I decided to join and post my own thread.

    The problem
    I was watching the TV one day and just heard a slight pop/hiss sound like the noise the TV used to make when I first turned it on and and after that the screen went black but the sound continued. When I turn it on now I don't hear the noise it used to make when turning on and there is no sign of life on screen. When I shine a light on it I can see the picture faintly so I know it's the backlight.

    What I've tried so far
    My friend also bought the same TV on the day I bought mine and I had him bring his Woking one over and we opened them both up. when I switched the main power board (the one the ac plug slots into) my TV worked perfectly(including the little little noise I used to hear when I turned it on first pre-problem) so I know the problem is with that board. Next, after reading some posts here about similar problems I checked all the caps on the board and although none looked to be bulging or damaged I decided to change them all jus to be safe and because it seemed like the easiest solution but after ordering the caps and changing them all today I still have the same problem.

    I'm wondering where I should go from here to fix this as this is a relatively new TV It had just gone out of warranty when the problem happened and I don't want to have to scrap it already and I've tried to find a replacement board for it on the net but it proving very difficult. Also probably worth saying I'm in Ireland where we run on 220v power.

    I appreciate any help you can give me and will keep this post up to date.

    Cheers lads,

    Dave

    #2
    Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

    To get the best help,I would post good and clear pictures off the boards.
    specially the main board in this case,try a few close ups from the front AND the back of the board,try and include a pic of the plug that runs from the powerboard to the mainboard as well,so the guru's here can see what voltage etc goes where...
    I resize my pictures with the windows feature to large,but lower MB's....easier uploading that way
    Proud owner of dozens of broken TV's and many,many,many boards.


    Our website and passion:http://hollenhundshepherds.com/

    Comment


      #3
      Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

      Thank you I will get pictures up as soon as I can when I get home this evening

      Comment


        #4
        Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

        These are the photos I have taken if there are any more needed please let me know
        Attached Files

        Comment


          #5
          Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

          since you have a combo board I would check to see if the mosfets feeding the inverter are shorted out, then look for an open resistor feeding them. I outlined some suspects for you to test.
          Attached Files
          Liberating magic smoke one part at a time

          Comment


            #6
            Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

            Thanks for the reply, I have a multi meter here but haven't done any testing on these kind of things before, what am I lookin for when I test it?

            Comment


              #7
              Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

              The mosfets should read high ohms (several kohms and up) between the three legs of each mosfet, the resistors should match the value printed on them. you can use diode mode to check the mosfets as well if you get a continuous beep then you likely have shorted components.
              Liberating magic smoke one part at a time

              Comment


                #8
                Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                Tried to test today but I got a spark and crackle out of it and decided I might be in too deep:/ I've never done this before but the way I attempted it on the advice of a similarly clueless friend was set the dmm on ohms and touched the black lead on an earth and the red one on a leg of the mosfet and got a high reading for a second but when I tried to touch it again it sparked and some smoke came out of it so I haven't touched it again. Have I blown it beyond repair now?

                Comment


                  #9
                  Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                  Also I had the TV plugged into the mains which I'm not sure I should have had?

                  Comment


                    #10
                    Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                    any resistance checks are usually made with the tv unplugged from the power supply voltage checks on the other hand yes you need it plugged in.

                    Comment


                      #11
                      Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                      Any idea why I had the sparks out of it? Was I testing the most et wrong?

                      Comment


                        #12
                        Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                        the set needs to be un plugged was it? i guess a capacitor may of stored some voltage but my guess is you had it plugged into the mains socket.

                        Comment


                          #13
                          Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                          Yeah I had it plugged into the mains. I have checked it now while it's plugged out and the resistors are all giving a reading matching their given values but I'm unsure of how to test the mosfets?

                          Comment


                            #14
                            Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                            Well if you let the magic smoke out of those mosfets they will need replaced for sure now. You should always have the set unplugged when testing for faults on the power board, also a good idea to discharge the main caps with a large resistor before working on it. once you have verified all the components are ok then you plug it in to do voltage checks. You likely shorted the lead with a stored charge to ground, Sometimes if you only get an arc it doesnt do any lasting damage, but if your mosfets were smoking they are done for.

                            youtube on testing mosfet
                            Last edited by Caleb; 04-26-2014, 08:46 AM.
                            Liberating magic smoke one part at a time

                            Comment


                              #15
                              Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                              Yes I reassembled the TV and tried to turn it on but it doesn't even have the red light on it now so I guess I'll have to replace the mosfets I blew before I can go any further? Would I have caused damage to anything else I would need to replace doin that?

                              Comment


                                #16
                                Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                                could have fried the controller ic as well as probably blowing the fuse
                                Liberating magic smoke one part at a time

                                Comment


                                  #17
                                  Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                                  So is it beyond repair at this stage considering the fact I have no experience in doing this?

                                  Comment


                                    #18
                                    Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                                    I wouldnt say beyond repair, but it may be difficult. You may be able to send it in to shopjimmy or moduslink to have it fixed or just find a replacement power board off the net.
                                    Liberating magic smoke one part at a time

                                    Comment


                                      #19
                                      Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                                      Yeah I think it's gone beyond me fixing it at this stage now, I have searched for a replacement board for it but I'm finding it very difficult to find one and there is nowhere local that will fix it for me. I think I'll have to try find somewhere online that can repair it for me.

                                      Comment


                                        #20
                                        Re: 42pfl3606h/12 Phillips tv powersupply/backlight problem

                                        Maybe inbox tom66? You are in Ireland and he is in the uk somewhere. Maybe you guys can work out a deal?
                                        Proud owner of dozens of broken TV's and many,many,many boards.


                                        Our website and passion:http://hollenhundshepherds.com/

                                        Comment

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