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Multimedia projector, blown psu

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    Multimedia projector, blown psu

    Hi everyone.
    This is PSU from a NEC projector.
    A spring got loose and shorted to ground under q201.
    Blown parts found so far:
    top side
    fuse ( t5ah/250vac )
    r115
    q201
    r214 ( no ohm readings )
    d301 ( passing current in both directions )
    d302 ( passing current in both directions )
    bottom side
    r208 ( no ohm readings )
    r207 ( no ohm readings )

    If I change the above parts will this psu work fine or there are other components which might have blown?
    Also, can anyone help with the specs of r208 and r207?
    I found a service menu, but there are no schematics for the psu there .
    Attached Files
    Last edited by madan1; 06-15-2017, 10:49 AM.

    #2
    Re: Multimedia projector, blown psu

    Have you tried to get a used one? search for ZSNE834I might be cheaper to replace than repair.

    Comment


      #3
      Re: Multimedia projector, blown psu

      The way i see it , R208 is 180 Ohms and R207 is a fuse bridge 000..
      It's not bad to check all the SM resistances for outranged values .

      Comment


        #4
        Re: Multimedia projector, blown psu

        Originally posted by R_J View Post
        Have you tried to get a used one? search for ZSNE834I might be cheaper to replace than repair.
        There are few second hand ones, but I wouldn't call them "cheap". I do not know how many hours are on the lamp, so I prefer to keep the repair costs as low as possible.

        The way i see it , R208 is 180 Ohms and R207 is a fuse bridge 000..
        It's not bad to check all the SM resistances for outranged values .
        Yeah, I also thought so.
        The fat path from the burnt resistor goes straight to IC202. Unfortunately the label has faded and it reads something like 2A09d23 which is not recognized as IC . IC101 is a switch/booster and with a totally different label.

        Comment


          #5
          Re: Multimedia projector, blown psu

          Originally posted by madan1 View Post
          There are few second hand ones, but I wouldn't call them "cheap". I do not know how many hours are on the lamp, so I prefer to keep the repair costs as low as possible.


          Yeah, I also thought so.
          The fat path from the burnt resistor goes straight to IC202. Unfortunately the label has faded and it reads something like 2A09d23 which is not recognized as IC . IC101 is a switch/booster and with a totally different label.
          Since the label is missing , no schema , the only option now is to bet on a blown bridge fuse R207 while IC202 remained protected after it . You can put a temporary 1 or 2A Fuse for more safety testing .

          Comment


            #6
            Re: Multimedia projector, blown psu

            R207 is part of the Gate drive circuit which is driven by SMPS IC202 which is probably bad for sure now.
            Can you read all the printings on top of that IC202 and tell us what they are?
            Never stop learning
            Basic LCD TV and Monitor troubleshooting guides.
            http://www.badcaps.net/forum/showthr...956#post305956

            Voltage Regulator (LDO) testing:
            http://www.badcaps.net/forum/showthr...999#post300999

            Inverter testing using old CFL:
            http://www.badcaps.net/forum/showthr...er+testing+cfl

            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
            http://s807.photobucket.com/user/budm/library/

            TV Factory reset codes listing:
            http://www.badcaps.net/forum/showthread.php?t=24809

            Comment


              #7
              Re: Multimedia projector, blown psu

              Here are the best images I can take of that IC.


              line 1 - *A*9D23
              line 2 - 5528

              I'm almost 100% sure that the first character is "2", but the third one is a mystery
              Attached Files
              Last edited by madan1; 06-16-2017, 04:00 PM.

              Comment


                #8
                Re: Multimedia projector, blown psu

                5528 ..
                http://www.datasheet-pdf.com/PDF/FA5...lectric-729037

                Comment


                  #9
                  Re: Multimedia projector, blown psu

                  Originally posted by petehall347 View Post
                  THANK YOU!

                  I didn't even think about searching for the 4 digits.. I thought this was a production date or something

                  The IC seems to be fine.. no shorted pins, but the diode d209 between the ground and the output ( pins 4 and 5 ) was shorted ( current in both directions ).

                  Also, in the IC documentation, page 16, the connection to the mosfet is straight, so the guess for "000" r207 was correct ( points go to jiroy ).


                  So the things are starting to get clear - the power surge got almost everything in that rail

                  Comment


                    #10
                    Re: Multimedia projector, blown psu

                    Maybe have a look at page 33 two resistors in series one is 100 ohm one is 10 ohm
                    Last edited by R_J; 06-16-2017, 06:29 PM.

                    Comment


                      #11
                      Re: Multimedia projector, blown psu

                      Originally posted by R_J View Post
                      Maybe have a look at page 33 two resistors in series one is 100 ohm one is 10 ohm
                      No "1" for sure.

                      By the way, in the sample, for transistor is used 2sk3687.
                      Will it be ok to use 3687 ( which seems to be more easily obtainable ) instead of 2sk3564?
                      Attached Files

                      Comment


                        #12
                        Re: Multimedia projector, blown psu

                        For that Gate drive resistor to burn up like that, large amount of current has to flow through the resistor and through pin 5 output pin of that IC, so more likely the circuit om the output of the IC has gone open circuit. I WOULD replace that IC for sure.
                        Attached Files
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment

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