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Samsung PS50C450 Totally Dead

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    #1

    Samsung PS50C450 Totally Dead

    Hello

    I have a Samsung PS50C450 plasma (PS50C450B1W to be exact) and it is totally dead when power is applied. No lights, no clicks, absolutely nothing at all.

    I wrongly assumed that the power board was at fault and replaced it with a known good one, but it has made no difference.

    As far as I can see, nothing is burnt out on any of the boards. All caps appear fine. I've checked the obvious things like fuses and there is definitely power coming through the lead.

    Would anybody be able to suggest which board to try next, before I end up wasting time and money replacing the wrong boards? Or are there any specific tests/measurements I can do to try and narrow down where the fault might lie?

    Thanks very much in advance.
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    #2
    Re: Samsung PS50C450 Totally Dead

    I would check the power board first ,you can check in the set or out, you need to pull all the plugs apart from the mains lead from the board, first check 5vstby you will find this on the socket that goes to the main board, if you have that, on the same socket you will see a pin marked PSon if you ground that the relay should click and the small voltages should come up, then you will need a resistor 500-1000ohm to go between 5vstby and VSon to bring up the VS supply. try this and post findings

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      #3
      Re: Samsung PS50C450 Totally Dead

      Thanks for the response.

      OK so STD5V, as it is called on my board, gives me 5.26v. PS_ON to ground does indeed cause the relay to click.

      I've connected a 750ohm resistor between STD5V and VS_ON. This is not giving me any Vs reading whatsoever. I've tried both boards and both give me the same result.

      I'm measuring Vs to ground, is that correct? Also the STD5V and VS_ON seem to be on separate sockets, presumably this should be the case.

      Thanks in advance.

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        #4
        Re: Samsung PS50C450 Totally Dead

        Apologies, I misunderstood your instruction. I was measuring Vs without having PS_ON connected to ground. I've now measured Vs at 212v.

        The resistor I used is actually a 1000ohm not a 750 as I first thought, if that is of any relevance.

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          #5
          Re: Samsung PS50C450 Totally Dead

          right so we now know the power boards are working ,and you are not getting any relay click when you power from the remote or side buttons ? so I think its main board we can check this next, connect all the plugs back in to the power board apart from the main board plug, on the control board you will see four pins numbered 1-4 join pins 3+4 put your power board back with PSon to ground, with set plugged into mains it should run screen test, if this runs as it should then you have proved the main board to be faulty and not sending PSon to power board, run this and report your findings

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            #6
            Re: Samsung PS50C450 Totally Dead

            Brilliant, thank you! By doing that I get the screen test. So the main board must be faulty.

            Is there anything worth checking on the mainboard that might be repairable before I buy a new one?

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              #7
              Re: Samsung PS50C450 Totally Dead

              Main board faults can be hard to find. and not having any PS on signal back to the power board is not a common fault, the normal fault is a relay click, so a PS on signal that is there for a second or two but does not stay on , you could backtrack on the board to fault find but it would be hard going? best maybe to find a replacement, you will need to match the numbers on the white bar code sticker BN92-xxxxxx that is the part number do not go by the screen printed number as that is the board type number only ( bare board and can be loaded with any components to cover lot of models ) hope this is of help and happy hunting

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                #8
                Re: Samsung PS50C450 Totally Dead

                I've managed to get hold of one that matches. For what it cost it's not worth spending any time searching for faults. I'll let you know how it goes when it arrives. Thanks again for all your help.

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                  #9
                  Re: Samsung PS50C450 Totally Dead

                  Was the main a BN94-03257K? I have just been out looking for a X/Y and Y buffer for a mate for his customers PS42B450 and found a load of mains that I forgot I had ,covered in dust in a box under my bench marked PS50C in with the 42" parts,one day I will have a tidy up

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                    #10
                    Re: Samsung PS50C450 Totally Dead

                    It was a BN94-03257U. Luckily the first one I came across matched it exactly.

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                      #11
                      Re: Samsung PS50C450 Totally Dead

                      Let us know when you have fitted it, I have a few showing that prefix as well boxes of the things, I will get round to listing them one day

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                        #12
                        Re: Samsung PS50C450 Totally Dead

                        The board arrived today. Fitted it in 2 mins and the TV is now working perfectly again

                        Thank you so much for your help.

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                          #13
                          Re: Samsung PS50C450 Totally Dead

                          just pleased I could help ,enjoy you viewing Flocko

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