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Samsung UE32EH5000W dead

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    #1

    Samsung UE32EH5000W dead

    This TV suffered a mains overvoltage during a storm and the power board died.
    I found the fuse and one ceramic capacitor burned.
    The board is bn44-00665a. I could not find the schematics diagram.
    https://assets.shopjimmy.com/media/c...00665a-top.jpg
    https://assets.shopjimmy.com/media/c...65a-bottom.jpg
    I replaced the capacitor and the fuse, I also replaced the MOSFET MMF60R750P.
    The TV is still dead, no standby or backlight.
    All voltages on CNM803 are zero except A5V which is 2.8V.
    On CNL802 I have D+=96V, S-=S+=82V, D-=87V.

    If I take out mainboard cable, I have on D+=79V, S-=S+=0, D-=72V
    On CNM803 all 13V pins have a voltage varying from 4.5V to 6.2V in a loop.
    And the 5V pins varies between 0.9V-1.6V.

    Can you help me with a diagram of this board or any other advice? Thanks.
    Tags: None
    #2
    Re: Samsung UE32EH5000W dead

    Check RM817, DM804, CM806 cap and J805 [000] resistor, Check what the voltage is across CM806
    It is possible the drive ic was damaged.
    Last edited by R_J; 10-12-2019, 06:49 PM.

    Comment

      #3
      Re: Samsung UE32EH5000W dead

      Originally posted by tiztiz View Post
      This TV suffered a mains overvoltage during a storm and the power board died.
      I found the fuse and one ceramic capacitor burned.
      The board is bn44-00665a. I could not find the schematics diagram.
      https://assets.shopjimmy.com/media/c...00665a-top.jpg
      https://assets.shopjimmy.com/media/c...65a-bottom.jpg
      I replaced the capacitor and the fuse, I also replaced the MOSFET MMF60R750P.
      The TV is still dead, no standby or backlight.
      All voltages on CNM803 are zero except A5V which is 2.8V.
      On CNL802 I have D+=96V, S-=S+=82V, D-=87V.

      If I take out mainboard cable, I have on D+=79V, S-=S+=0, D-=72V
      On CNM803 all 13V pins have a voltage varying from 4.5V to 6.2V in a loop.
      And the 5V pins varies between 0.9V-1.6V.

      Can you help me with a diagram of this board or any other advice? Thanks.
      dead capacitors are a pain to replace

      Comment

        #4
        Re: Samsung UE32EH5000W dead

        RM817=0
        DM804 ok
        CM806 ok
        J805=0
        on CM806 I have 11V

        p.s. CM801 was the capacitor I found burnt and with legs melted.
        On the back side looks strange the area around PC801S
        Attached Files
        Last edited by tiztiz; 10-13-2019, 03:46 AM.

        Comment

          #5
          Re: Samsung UE32EH5000W dead

          That voltage on CM806 should be the VCC for the ic, Is ICM801 a SEM3330? if it is I don't have a datasheet but 11v seems low and is likely being produced by the ic's startup cell only. You can test this by disconnecting one end of DM804 and rechecking the voltage on CM806, if it is the same 11v then the transformer is not producing the run voltage which should be closer to +20v.
          There is also a zener diode, ZDM803 which could be bad and zenering at too low a voltage.

          Comment

            #6
            Re: Samsung UE32EH5000W dead

            I removed the DM804 and the voltage on CM806 is looping between 9.3V-11V in a ~5 seconds cycle.
            The IC is ICM801=S3310.

            Comment

              #7
              Re: Samsung UE32EH5000W dead

              That voltage is supplied by the ic itself, once it pulses the transformer primary, the voltage in the secondary winding that feeds DM804 should supply the run voltage, check that the transformer winding is not open. When DM804 is in circuit it should supply around 20~25v to keep the ic running

              Comment

                #8
                Re: Samsung UE32EH5000W dead

                I don't have the diagram so I don't know how the transformer windings should look like, but I can measure zero impedance between first two pins and between next two pins. There is no connection between pins 1,2 and pins 3,4. I guess the transformer looks fine ?

                Comment

                  #9
                  Re: Samsung UE32EH5000W dead

                  The transformer will be ok, Ground connects to J809/814 jumpers and the secondary run winding connects to RM817. If you look at the datasheet for a FAN6755W, it is a similar ic.
                  You said you had: A5V which is 2.8V which suggests the circuit is trying to start up. Check that you don't have a shorted diode in the secondary side (DM861,DM873 etc)
                  It could be that the ic itself is damaged and will not come out of pulse mode. or maybe the optocoupler is bad? that could also cause the problem
                  There are also a couple resistors going from pin3 (sense pin) and the source pin of QM801CS, check that they are not open
                  Last edited by R_J; 10-13-2019, 05:52 PM.

                  Comment

                    #10
                    Re: Samsung UE32EH5000W dead

                    I replaced ICM801 with a 6755W.
                    I replaced PC801S (optocoupler) with a PC817.
                    Now, with the board disconnected I have on CNL802 D+=48V and D-=43V
                    On CNM803 there is only 1.7V on pin 12 (A5V), nothing on the other pins.
                    On CM806 voltage varying between 9V and 14V.
                    Diodes seems ok, resistors ok ...

                    Comment

                      #11
                      Re: Samsung UE32EH5000W dead

                      I cannot find anything wrong on the HOT side. Can it be in the Cold side?

                      Comment

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