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    #1

    LG 42PC3D-UD No picture just sound

    My LG 42PC3D plasma TV suddenly stops working. It would turn on but I would get no picture. I tried shinning a bright LED flashlight on the screen but I still didn't see any color. So I did a little research and found that this is probably caused by the YSUS or ZSUS board. So I ran several testes according the information I found.

    1) I removed the power cable to either YSUS or the ZSUS board. The TV will still turn on with sound.
    2) I took off the back panel and tested the 4 fuses with a DMM. I found that one of the fuses on the YSUS board was not working.
    3) I also felt the temperature of both heat sink after about 10-20 min of use and the ZSUS was cold while the YSUS was moderately warm.
    4) I went to my local hardware store and bought a replacement fuse for the YSUS board. When I plugged in the new fuse, the TV will shut off on the own after I turn it on. If I removed the power to the YSUS board the TV will turn on and stay on.

    None of my symptoms matched either board exactly so now I'm totally confused on which IPM on which board is bad. Is it possible to have a short on my YSUS board and a bad IPM on my XSUS board at the same time?
    P.S. I checked the fuses by setting the DMM on 200 ohms and got about .3 .4 except the one on the YSUS where I didn't get anything. I also uploaded a couple pictures of my boards in case you anyone need to look at them. I'll greatly appreciate anyone who can help me fix my TV.
    Attached Files
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    #2
    Re: LG 42PC3D-UD No picture just sound

    Originally posted by Thanhtran0391 View Post
    My LG 42PC3D plasma TV suddenly stops working. It would turn on but I would get no picture. I tried shinning a bright LED flashlight on the screen but I still didn't see any color. So I did a little research and found that this is probably caused by the YSUS or ZSUS board. So I ran several testes according the information I found.

    1) I removed the power cable to either YSUS or the ZSUS board. The TV will still turn on with sound.
    2) I took off the back panel and tested the 4 fuses with a DMM. I found that one of the fuses on the YSUS board was not working.
    3) I also felt the temperature of both heat sink after about 10-20 min of use and the ZSUS was cold while the YSUS was moderately warm.
    4) I went to my local hardware store and bought a replacement fuse for the YSUS board. When I plugged in the new fuse, the TV will shut off on the own after I turn it on. If I removed the power to the YSUS board the TV will turn on and stay on.

    None of my symptoms matched either board exactly so now I'm totally confused on which IPM on which board is bad. Is it possible to have a short on my YSUS board and a bad IPM on my XSUS board at the same time?
    P.S. I checked the fuses by setting the DMM on 200 ohms and got about .3 .4 except the one on the YSUS where I didn't get anything. I also uploaded a couple pictures of my boards in case you anyone need to look at them. I'll greatly appreciate anyone who can help me fix my TV.
    The symptoms certainly indicate you have a bad Y-sustain. There have been a few reports of simultaneous failures but this is rare. The hybrid is likely bad; although the 15V supply has been considered a cause of this failure.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment

      #3
      Re: LG 42PC3D-UD No picture just sound

      Originally posted by PlainBill View Post
      The symptoms certainly indicate you have a bad Y-sustain. There have been a few reports of simultaneous failures but this is rare. The hybrid is likely bad; although the 15V supply has been considered a cause of this failure.

      PlainBill
      First, thank you PlainBill for taking the time to help me out. I have been going through this forum a lot and saw that you helped a lot people with similar problems as mine. I was wondering if you can give me a more detailed instruction on how to make sure it's the hybrid on the YSUS board. I'm planning to buy a hybrid off of eBay and soldering it on myself. If I do it that way can I avoid getting someone with a scope to tune it afterwards? Also about the 15v supply that you mentioned, could you tell me how to check if it's bad or not. And just out of curiosity can you explain to me why the Heat sink on the ZSUS is cold but it didn't blow any fuses. Thanks again PlainBill for helping me out, I really do appreciate it.

      Comment

        #4
        Re: LG 42PC3D-UD No picture just sound

        Originally posted by Thanhtran0391 View Post
        First, thank you PlainBill for taking the time to help me out. I have been going through this forum a lot and saw that you helped a lot people with similar problems as mine. I was wondering if you can give me a more detailed instruction on how to make sure it's the hybrid on the YSUS board. I'm planning to buy a hybrid off of eBay and soldering it on myself. If I do it that way can I avoid getting someone with a scope to tune it afterwards? Also about the 15v supply that you mentioned, could you tell me how to check if it's bad or not. And just out of curiosity can you explain to me why the Heat sink on the ZSUS is cold but it didn't blow any fuses. Thanks again PlainBill for helping me out, I really do appreciate it.
        First of all, I have repaired some of these TVs in the past, but don't have a real grasp of how plasma displays work. Yeah, I've read the training manual, but that doesn't really tell me where the current is going. For what it's worth, here's my two bit explanation. A plasma display works much like a CCFL, a high voltage is generated between two electrodes, creating a discharge of high energy photons, which strike a phosphor coating causing it to glow. Now imagine if the Z-sus is driving one of the electrodes low while the Y-Sus (and buffer) is driving the other one high. The current used in the discharge is flowing through the Y buffers and the Z-sustain. If the current is not flowing, the Z-sustain isn't handling the current. Even though the fuse has blown, the Y-sustain is still driving the buffers, so it is handling some current. Now at this point the guys who really understand plasma TVs may be rolling on the floor laughing at me.

        Here's an account from someone with a similar problem.

        PlainBill
        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

        Comment

          #5
          Re: LG 42PC3D-UD No picture just sound

          Is it the lighting or my imagination, but there are 4 caps on the power board that look bloated to me?
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            #6
            Re: LG 42PC3D-UD No picture just sound

            Originally posted by PlainBill View Post
            First of all, I have repaired some of these TVs in the past, but don't have a real grasp of how plasma displays work. Yeah, I've read the training manual, but that doesn't really tell me where the current is going. For what it's worth, here's my two bit explanation. A plasma display works much like a CCFL, a high voltage is generated between two electrodes, creating a discharge of high energy photons, which strike a phosphor coating causing it to glow. Now imagine if the Z-sus is driving one of the electrodes low while the Y-Sus (and buffer) is driving the other one high. The current used in the discharge is flowing through the Y buffers and the Z-sustain. If the current is not flowing, the Z-sustain isn't handling the current. Even though the fuse has blown, the Y-sustain is still driving the buffers, so it is handling some current. Now at this point the guys who really understand plasma TVs may be rolling on the floor laughing at me.

            Here's an account from someone with a similar problem.

            PlainBill
            After reading that post above, I really want to check the 15v supply on my set too. But unlike him I don't have years of experience, only a broken TV and a willingness to learn. Can you tell me where and how to check it with my multi meter.

            Comment

              #7
              Re: LG 42PC3D-UD No picture just sound

              Originally posted by retiredcaps View Post
              Is it the lighting or my imagination, but there are 4 caps on the power board that look bloated to me?
              Are you talking about the 4 big ones or the 4 smaller ones in the lower left corner? Because the 4 smaller ones doesn't look swollen in real life. Maybe it is the lighting.

              Comment

                #8
                Re: LG 42PC3D-UD No picture just sound

                Originally posted by Thanhtran0391 View Post
                Because the 4 smaller ones doesn't look swollen in real life. Maybe it is the lighting.
                Sorry, I thought I wrote lower left, but apparently not.

                Well it must be the angle and lighting then.
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                Please do not post inline and offsite as they slow down the loading of pages.

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                Comment

                  #9
                  Re: LG 42PC3D-UD No picture just sound

                  Originally posted by Thanhtran0391 View Post
                  After reading that post above, I really want to check the 15v supply on my set too. But unlike him I don't have years of experience, only a broken TV and a willingness to learn. Can you tell me where and how to check it with my multi meter.
                  I have a clue, but I don't have a Y-sus to examine. I would need a good quality picture of the bottom of the Y-sus.

                  PlainBill
                  For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                  Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                  Comment

                    #10
                    Re: LG 42PC3D-UD No picture just sound

                    Originally posted by PlainBill View Post
                    I have a clue, but I don't have a Y-sus to examine. I would need a good quality picture of the bottom of the Y-sus.

                    PlainBill
                    Here's a picture of the bottom of the board. And after a second look at the supply board those 4 cap does look a little swollen from the side. I checked the fuse on that board and its fine. Should I go ahead and replace those too.
                    Attached Files

                    Comment

                      #11
                      Re: LG 42PC3D-UD No picture just sound

                      those caps are definitely bad. there's also a hint of dried up electrolyte on them..
                      this is why i hate Samwha
                      Last edited by Scenic; 02-23-2011, 09:17 PM.

                      Comment

                        #12
                        Re: LG 42PC3D-UD No picture just sound

                        guys, nice tread! im having a simular problem. wile looking at tv heard a pop discovered a fuse in the ysus chanced the fuse and it keeps popping,the tv would not come on just a click. i decided to changed the ysus now ths set is coming on but no picture and no sound the screen will light up a little kinda looks like a backlight is on. please help......

                        Comment

                          #13
                          Re: LG 42PC3D-UD No picture just sound

                          Originally posted by cats View Post
                          please help......
                          and more multiple postings.
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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.

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                            #14
                            Re: LG 42PC3D-UD No picture just sound

                            Originally posted by Scenic View Post
                            those caps are definitely bad. there's also a hint of dried up electrolyte on them..
                            this is why i hate Samwha
                            I found the same bad caps. Where do I get the replacements?

                            Comment

                              #15
                              Re: LG 42PC3D-UD No picture just sound

                              Originally posted by Sinbad View Post
                              I found the same bad caps. Where do I get the replacements?

                              I have the same set. All 9 of the 3300uF 10V caps in the power supply were leaking / high ESR. All replaced, fuse on y sus blown. Swapped for another ysus, but of unknown quality as it came froma set with a blown hybrid IC on the Z Sus. Hear a ticking sound on the Y sus board. The Z sus has the familiar 60hz buzz. Picture flickers with this ticking. Any ideas? Bad Y sus I suspect.

                              Comment

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