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Samsung Plasma PN51F5300 not turning on

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    Samsung Plasma PN51F5300 not turning on

    Product: Samsung Plasma TV (PN51F5300)

    Initial symptoms:
    In-laws were downstairs watching tv when they heard a pop and the screen went out.
    When resetting power and turning on again, front light blinks red a few seconds and goes out: tv is otherwise unresponsive until power is cycled again.

    Initial investigation: Remove back from Plasma TV, armed with DMM.
    No obvious capacitor bulging on any visible boards.
    Power connected, turned on: green LED on main board repeats a pattern of short-long (1 second total) on, one second off. Repeats five times.
    Power supply makes soft clicking sounds and high pitched tone when main board LED is lit, but stops when LED is off.
    VS and VA test points vary during 5 startup attempts, neither getting higher than 1V - drop to 0 after startup attempts end.
    Confirmed on main board that Standby (obviously), V15, and V5.3 are being generated.

    Additional investigation: unseat cable between Power Supply board and X sustain from PS end.
    Power connected, turned on: green LED blinks regularly, optical port turns on (red light visible).
    At startup, Va max voltage is ~58V, but rapidly falls off. Vs max voltage is ~225, same falloff observed.
    Va is near specified voltage (58V), but VA is high (specified as 209V).
    Vs adjusted as low as trim allows, but only observed max voltage at turnon as 223V.

    Any troubleshooting recommendations or initial diagnoses welcomed!
    Attached Files
    Last edited by DancingElectron; 09-08-2020, 08:32 PM.

    #2
    Re: Samsung Plasma PN51F5300 not turning on

    Probably Y-sustain board / buffer board is dead
    Inspect Y-buffer board ICs for signs of burn
    check Y-Sustain board for shorted IGBTs

    Comment


      #3
      Re: Samsung Plasma PN51F5300 not turning on

      Zape, thanks: it's looking that direction - when I only disconnect the ribbon cable between the x-sustain and y-sustain boards, I get the same nominal-decay voltage on Vs/Va (vs. 5 cycles and quit).

      Will take a closer look and report back.
      Last edited by DancingElectron; 09-09-2020, 07:15 AM.

      Comment


        #4
        Re: Samsung Plasma PN51F5300 not turning on

        I had one that had the same symptoms as yours. I put a jumper in holes 3 and 4 on the mainboard/logic board and I got the test patterns to run for 9 seconds and then re-boot and run for another 9 seconds and.......
        My mainboard was bad. Replaced it with one from Ebay, and everything was good again.
        I was getting a screen flash but I forgot to check the VS and VA . Once I did, I found out it would be spot on, for 9 seconds. The mainboard has a logic board built in it. That's why the test patterns only ran for 9 seconds.

        Comment


          #5
          Re: Samsung Plasma PN51F5300 not turning on

          Thanks! I'm not familiar with the jumper self-test process you're describing: I'll do some research today, but any links or more description of what pins to short would be useful.
          Attached Files

          Comment


            #6
            Re: Samsung Plasma PN51F5300 not turning on

            Stick a paper clip in holes 3 and 4 then plug the tv in.
            Attached Files
            Last edited by tvtimmy; 09-10-2020, 04:28 PM.

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