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    #1

    Samsung plasma PN50A450P1DXZA

    Hello,

    I picked up this Samsung plasma PN50A450P1DXZA that had sound but no picture. The power supply tested good, but the Vscan voltage was bad and the Y-main was making a noise.

    I pulled the Y-main and found a shorted FET (80N30W) that was attached to the center heat sink. It was one of three ganged together so I decided to see if I could get something on the screen if I left the shorted one out. I would not run it like this but I figured it would be OK for testing. I also replaced a bad 63V 68uF cap that located under the over hang of this heat sink.

    After this the screen would turn on but it had a lot of issues and I could not even discern if it would show a menu. I thought that putting the control board into test mode would be the best way to tell if the screen was actually good. I know the Y-main is bad since one of the drivers gets way hotter than the rest and it shows heat discoloration.

    From my pictures, does it look like the screen itself is still good? Also, if the screen itself appears good, does it look like any of the other boards are showing signs of damage? I would like to repair this TV if possible but I do not want to waste time or money on something that will never work properly if I can help it. Any constructive input would be appreciated.

    Thanks.
    Attached Files
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    #2
    Re: Samsung plasma PN50A450P1DXZA

    Originally posted by LDSisHere View Post
    Any constructive input would be appreciated.
    Why do you always get the hard ones?
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      #3
      Re: Samsung plasma PN50A450P1DXZA

      Originally posted by retiredcaps View Post
      Why do you always get the hard ones?
      I just seem to be lucky that way.

      I afraid I have a problem on the E-buffer but what exactly I am not sure. It seems to work somewhat, but not as well as the rest of the panel. This board is not replaceable so if I cannot figure out what is causing the vertical band then this TV is worthless.

      Comment

        #4
        Re: Samsung plasma PN50A450P1DXZA

        Well, I re-soldered the 1 ohm resistors on the E-buffer in the area of the dark vertical stripe. This seemed to fix that problem as I could no longer see a vertical band. I was going to take of picture of the somewhat improved image when it appears that the Y-main bit the dust completely. I now again get nothing on the screen. The only thing getting hot on the Y-main now is the driver that was going bad. Just seconds after powering on the set the heat sink gets so hot you almost cannot touch it. It appears that if I am going to proceed with this set I must acquire a working Y-main and hope the rest of the boards are working properly.

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          #5
          Re: Samsung plasma PN50A450P1DXZA

          I have noticed plasma "repairs" seems to be more board swapping rather than component replacement. Repairing computer LCDs makes it easier for me to troubleshoot and understand LCD TVs. However, I prefer plasma over LCD when watching 1080p movies.
          Last edited by retiredcaps; 04-17-2013, 10:02 PM.
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            #6
            Re: Samsung plasma PN50A450P1DXZA

            You also should look at the main board ,i just replaced one in the same model # and history on this TV has been always the main board.

            http://www.moduslinkptstvboards.com/...8B-P25873.aspx

            Comment

              #7
              Re: Samsung plasma PN50A450P1DXZA

              I received my replacement Y-main today. I initially tested it in the control board test mode. On the green screen there was "sparkles" all over it, but adjusting the VS seemed to take care of this problem.

              Over all I am very pleased with it. I do have one concern and that is when the screen is black (like in the last picture) there is red showing up on the bottom third of the screen. It is not even, as it seems to rise toward the center of the screen. This does not show up during normal operation unless there is a lot of black on the bottom of the screen. If anyone has any ideas about the cause and possible solutions to this red area, I would love to hear them. I am not overly concerned with this red area, as this TV will mostly be used by the kids to play video games, but if it is a sign of an imminent problem I would like to address it.

              Attached Files

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                #8
                Re: Samsung plasma PN50A450P1DXZA

                A little bit of red on dark scenes = maldischarge. Play with Yrr/Yfr to taste; make sure Vs is at panel rating. (Don't touch Vs for maldischarge on these sets unless you absolutely have to.)

                Plasma repair is hard without a scope. There's nothing stopping you doing component level repair, but sometimes the parts are cheaper than the value of your time.
                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

                  #9
                  Re: Samsung plasma PN50A450P1DXZA

                  Originally posted by tom66 View Post
                  A little bit of red on dark scenes = maldischarge. Play with Yrr/Yfr to taste; make sure Vs is at panel rating. (Don't touch Vs for maldischarge on these sets unless you absolutely have to.)

                  Plasma repair is hard without a scope. There's nothing stopping you doing component level repair, but sometimes the parts are cheaper than the value of your time.
                  Thanks for taking the time to look at this and reply.

                  I found the page in the service manual about the V-RR and V-FR adjustment. It looks like it is best done with a scope so I will leave it until I have one. (I am currently looking to get a scope but I have not yet decided on what I want to get.)

                  I agree with your assessment of the component level repair cost. If possible I would like to do the repairs myself if for no other reason than the learning experience. However in this case, the original Y-main had a bad driver chip which would be impossible for me to change at this point so I had little choice but to get another Y-main. I was able to get one for $45 including shipping, so at that price, replacing it was the only sensible thing to do. I was just glad it was the only board with a major problem.
                  Attached Files

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                    #10
                    Re: Samsung plasma PN50A450P1DXZA

                    While a scope is recommended, it is not necessary. You can do it entirely by eye. Long term maldischarge is potentially damaging to the panel due to the sporadic, high-energy discharges in the panel. (Such damage would more or less be like burn in, or a darkening image.)
                    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

                      #11
                      Re: Samsung plasma PN50A450P1DXZA

                      Since I do not know how long it will be until I get a scope I think I will try to do as suggested and adjust the V-RR and V-FR by eye. I tried searching for information on a good setup to accomplish this, however I could not find any suggestions. Therefore I have a couple of questions before attempt this process.

                      1. What would be a good image(s) to use while adjusting the TV? (still image, video, solid black, busy scene with lots of colors, etc.)

                      2. Which input would be the best to use while adjusting the TV? (cable, HDMI, etc)

                      I figure what you are looking at while doing the adjustment will greatly influence the final result. I would greatly appreciate any input on this matter.

                      Thanks!

                      Comment

                        #12
                        Re: Samsung plasma PN50A450P1DXZA

                        The best scene is ordinary TV -- honest! That way you can see the effect on an ordinary, moving image. I have a slideshow of images I sometimes loop through but usually it's not that necessary.

                        As far as what I am looking at: Sparklies, image retention and black level.
                        Last edited by tom66; 04-21-2013, 04:21 PM.
                        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

                          #13
                          Re: Samsung plasma PN50A450P1DXZA

                          Originally posted by LDSisHere View Post
                          I am not overly concerned with this red area, as this TV will mostly be used by the kids to play video games, but if it is a sign of an imminent problem I would like to address it.
                          I was lucky to get 3 meals a day growing up!!
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                          If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                          Please do not post inline and offsite as they slow down the loading of pages.

                          --- end sig file ---

                          Comment

                            #14
                            Re: Samsung plasma PN50A450P1DXZA

                            Originally posted by tom66 View Post
                            The best scene is ordinary TV -- honest! That way you can see the effect on an ordinary, moving image. I have a slideshow of images I sometimes loop through but usually it's not that necessary.

                            As far as what I am looking at: Sparklies, image retention and black level.
                            Thank you for your reply. This was exactly the information I was wanting. I will hopefully get it adjusted before the end of this week.

                            Originally posted by retiredcaps View Post
                            I was lucky to get 3 meals a day growing up!!
                            I have to say, most kids today do not realize how good they have it, mine included. The current proliferation of electronics is definitely a double edged sword that may at this point be doing more harm than good.

                            Comment

                              #15
                              Re: Samsung plasma PN50A450P1DXZA

                              Hi im new. Im having a simular issue, same model plasma tv. Im fairly certain its the main center plasma board itself causing the black vertical center bar. Ive tested all inputs and its on top of all menus. Any tips on replacement? Whats the part called and how delicate a proceedure?
                              Attached Files

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                                #16
                                Re: Samsung plasma PN50A450P1DXZA

                                Originally posted by newtechexpert View Post
                                Hi im new. Im having a simular issue, same model plasma tv. Im fairly certain its the main center plasma board itself causing the black vertical center bar. Ive tested all inputs and its on top of all menus. Any tips on replacement? Whats the part called and how delicate a proceedure?
                                Two possibilites. Most likely is a bad plasma panel to be honest. It is common on these models. If it is not a panel issue it would probably be that center X board.
                                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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