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Samsung PN64D8000 - Power Supply Board Issue?

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    Samsung PN64D8000 - Power Supply Board Issue?

    We were watching TV the other night when I heard a pop followed by the TV going out. No standby light, nothing.

    Immediately, I opened the back and noticed that one of the fuses on the board (BN44-00447A) had blown. I thought I could replace the fuse and cross my fingers that nothing else was bad. I replaced the fuse and plugged in the TV, immediately the other one popped. I replaced that one and plugged back in and this time around I heard/saw a pop, which tripped the circuit breaker. This time around, a thermistor blew.
    I'm thinking that before I replace that thermistor, something else is amiss.

    It seems that these boards are a little hard to come by and not cheap. It's been a little while since I picked up a soldering iron (last time I did, I accidentally fried a PS2) so I'm hoping I can get some guidance on where to start.

    Thanks,
    J

    #2
    Re: Samsung PN64D8000 - Power Supply Board Issue?

    Usually there is a reason why a fuse pops. So keep putting in fuses you may do more damage. First off you have to figure out "WHY" the PSU keeps popping fuses. So first logical thing is to do is to make some straight shot, high resolution pictures of your boards front and back, so we can see things clearly. Check the primary section of the PSU. Be careful, there can be very high voltages when plugged in and running. Fist item to check on your PSU in this case is the bridge rectifier for a short. If that is shorted, it's bad.

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      #3
      Re: Samsung PN64D8000 - Power Supply Board Issue?

      What "thermistor" blew, it was likey an MOV. what was its location number or part number on the component. These boards also develope bad solder connections on the transformers and mosfets mounted to the heat sinks, they need resoldering especially the connections that use a rivit.

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        #4
        Re: Samsung PN64D8000 - Power Supply Board Issue?

        This is the thermistor that blew. I'm going to pull the board and see if I can see any other damage.

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          #5
          Re: Samsung PN64D8000 - Power Supply Board Issue?

          Sorry, didn't attach the image. DSC 20D-20 Thermistor. See the blow hole on the bottom right side.
          Attached Files

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            #6
            Re: Samsung PN64D8000 - Power Supply Board Issue?

            Ok, that one is the thermistor, Also check the resistance across the blue mov's maybe one of them shorted also, if not just replace the thermistor and don't forget to check or resolder those connections I mentioned.

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              #7
              Re: Samsung PN64D8000 - Power Supply Board Issue?

              Also have a blown MOSFET. See the pinhole and the char mark.
              Attached Files

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                #8
                Re: Samsung PN64D8000 - Power Supply Board Issue?

                That would do it. Did you have a look at those other connections for cold solder joint? I bet one of the connections on TS801s primary is bad.
                Last edited by R_J; 06-15-2018, 04:49 PM.

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                  #9
                  Re: Samsung PN64D8000 - Power Supply Board Issue?

                  So, impatient as I am, I ended up picking up a TV on craigslist that had a broken panel for $30. Power supply was good so I just swapped it to this one and I'm back in business, but will eventually fix this one as a backup.

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