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    Beko/Panasonic Plasma 42B43 problem...

    Hi!

    Well, after I repaired my LG plasma a friend of mine called me to take a look at his old plasma TV. It's Excello 42B43, a BEKO rebrand with Panasonic plasma module, 2005.

    TV worked fine until recently he moved it to another house. After relocation TV worked for day or two and than died. TV was serviced two times long ago, there are some visible signs of lousy service job on secondary PSU ;-)

    When plugged in TV gets no standby light, no remote or any other button response, but screen has a little background glow.

    There are two PSU's inside. The bigger one on the left side is Panasonic PSU, part of their plasma module, and smaller one on the right side made by Beko (model: Beko-PSU-03).

    After taking it apart I noticed blown fuse on secondary PSU. Secondary PSU (smaller one) made by Beko supplies low voltages to main video I/O board (+5V/+12V, standby, etc...)
    There was visible solder job at left upper corner, two caps, bridge rectifier and one small IC was replaced before. I did some cleaning and resoldering because the big cap at the corner was little bit loose, installed new fuse, plugged it in, relay clicked and after few seconds fuse exploded.

    Now, I found schematics for this particular PSU, poked a little bit with multimeter and ESR meter, can't find anything shorted or bad...

    I believe the problem is on the primary side of PSU. If it's on secondary I doubt fuse should explode like this.

    What do you think?? What plasma module type is it, btw?

    C1031, C1024, D1001 bridge and IC1004 were replaced before. What is IC1004 (FSD200) for?

    Attached schematics is for Beko-PSU-03 (pictures: Beko_42B43_PSU_01.jpg and Beko_42B43_PSU_02.jpg)


    Cheers!

    Suad
    Attached Files

    #2
    Re: Beko/Panasonic Plasma 42B43 problem...

    I do like Panasonic plasma modules. Very well engineered. They are the best, after Pioneer (but they don't exist any more.) The operation is more or less the same as your LG, although voltages are labelled differently, and no hybrids are used (props to Panasonic for doing it all in discretes.) Screen glow indicates that the PDP is probably still working, including all sustains and PSU.

    Shame then to see with such a nicely engineered PDP, what crappy sub-PSU they put with it !

    I would put in a new fuse, and see if it goes bang. If not, you fixed it. Fuse can blow from wear and tear (lots of turn on cycles, could be worsened by vibration.) If new fuse goes bang, then suspects are the bridge rectifier or power MOSFET. Looks like the bridge has already had a dodgy repair, so I'd try that first.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment


      #3
      Re: Beko/Panasonic Plasma 42B43 problem...

      Yes I replaced the fuse after I resoldered possibly loose cap. Relay clicked, and after few seconds fuse blew again. Bridge rectifiers check ok when I test them with multimeter. Also checked all diodes and FET's, nothing is shorted. Well OK, it doesn't have to be shorted to be bad... Did you take a look at the shematics?

      Comment


        #4
        Re: Beko/Panasonic Plasma 42B43 problem...

        Btw, new fuse literally exploded! My friend and me almost had a heart attack ;-)

        Comment


          #5
          Re: Beko/Panasonic Plasma 42B43 problem...

          Desolder the bridges and check. There must be a short. If possible, can you feed it from a variable DC power supply, current limited?

          Shattering fuse reminds me of this... https://www.badcaps.net/forum/showpo...26&postcount=5
          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

          Comment


            #6
            Re: Beko/Panasonic Plasma 42B43 problem...

            Originally posted by tom66 View Post
            Desolder the bridges and check. There must be a short. If possible, can you feed it from a variable DC power supply, current limited?
            I just found a possible problem. There is a serious burn in that corner. This blue cap C1023 looks quite busted. Take look at pics. See this two tiny wires on transformer?! Let's desolder it all out to take a closer look ;-)

            Stay tuned...

            Cheers!

            Suad
            Attached Files

            Comment


              #7
              Re: Beko/Panasonic Plasma 42B43 problem...

              Yep, looks like the safety cap which should never short under normal conditions (CE requirement)... has shorted.
              Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
              For service manual, schematic, boardview (board view), datasheet, cad - use our search.

              Comment


                #8
                Re: Beko/Panasonic Plasma 42B43 problem...

                Originally posted by tom66 View Post
                Yep, looks like the safety cap which should never short under normal conditions (CE requirement)... has shorted.
                Wow! Actually cap and diode are OK. They only got dirty when transformer TR1002 burned! These two tiny wires on the transformer primary are disintegrated. My doubt is, is it a cause for malfunction or consequence of some other malfunction on this PSU?!

                What shall I do now? What to put in the place of this transformer, how do I know it's specs??

                Suad
                Attached Files
                Last edited by scokljat; 08-07-2012, 05:05 PM.

                Comment


                  #9
                  Re: Beko/Panasonic Plasma 42B43 problem...

                  Th3_uN1Qu3 has detailed the processes for rewinding transformers; you might want to contact him. However, I suspect the failure is due to a shorted MOSFET.

                  You could replace the entire board. You might be able to get a broken screen version of this TV for very little - most go to the dump here.
                  Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                  For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                  Comment

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