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    fixed but got grainy/noise picture on my plasma now -LG 50PA6500

    last month my LG plasma 50PA6500 display turned black but sound was working,
    so after reading this forum i suspect it was either y-sustain board , or the y-buffer boards so i replaced y-sustain board first, did not worked,

    checked both y-buffer boards and found out lower one had a short IC, and that could have blown the new y-sustain board, so ordered a new y-sustain board and a new lower y-buffer board again, and now i got grainy/ snowy picture, see the pictures in this thread, ? is this panel gone bad now? any way to fix it? is there any other board i need to replace?
    any solutions? please help, I dont want this plasma to die.
    Thanks
    T
    Attached Files

    #2
    Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

    looks to me like the z-sustain board is also faulty.
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      #3
      Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

      I agree. x or z main

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        #4
        Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

        Thx..is there anyway to confirm thats its z board for sure before i order one. I do have a multimeter. Also im assuming my panel is fine..correct?
        Last edited by t333; 01-14-2017, 10:00 AM.

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          #5
          Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

          Waking up an old thread with the same/similar issue, didn't want to start another....while mine isn't as bad as the OP's, here we go! Alright Plasma experts......I've never worked on a plasma before, I slept through the entire plasma era.... One of this model was given to me the other day. My own forum with the help of THIS THREAD helped me pinpoint the power problem; the C802 fix....

          The original cap was reading 340pF......



          I replaced that and it powers up now.....but we're not out of the woods yet...



          There's a strange pixelization/ghosting image issue now. You can see in this image, the shadow of the 'color bars' in the menu:





          A movie playing, you can still see it:



          This board had a couple puffed lytics, I replaced them and reflowed anything I found even remotely questionable. This board has been miserably hot it seems...





          I did the onboard pattern generator procedure (disconnect P231 andshort the EXT_AUTO_GEN), got the same results. I also cleaned every LVDS cable end in the set with an eraser & isopropyl alcohol. Since the onboard test tells me the panel is likely OK as well as the main board, I connected my own pattern generator for some better revealing images of the issue:

          Color bars:





          White raster:

          The pixelization is visible, as well as the color bars shadowing; but it's not very clear in the pics. The white raster also doesn't seem to be as bright as it should be....



          Now this is what the white should look like... This image actually looks good, the white square is bright, clear, and nothing there that shouldn't be.



          Next one, you can clearly see both the pixelization and the previous patterns showing through (color bars AND the white box).





          Another where it can be seen:



          I know some of you are wondering why I'm wasting my time on this.....but I just want to... It seems to come & go at times, the brighter the scene in a movie, the more noticable it is....but for the most part, it has a darn nice picture....but sometimes its nasty! It's also hard to photograph this thing and keep my ugly face out of the reflective screen!!

          Anyway, of all the threads here on this model, I never could find a definitive answer/cure for this.....so help me out!
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            #6
            Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

            We have a plasma TV, too! Despite the brand is Emerson. (I think Funai owns them)
            But it sure has been trucking along! Year on the back, is 2009.

            Who's the real manufacturer? Did Funai even do manufacturing of plasma screens, per se???
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              #7
              Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

              Could be cracked solder joints on the big inductors on Y and Z SUS boards, or poorly adjusted SET_UP and SET_DN on Y-SUS, there are several trimpots on Y-SUS, Z-SUS and the power supply, they control VS, VA, -VY, VSCAN and Z-BIAS, these voltages should match what the white panel label specifies, you don't need to adjust those unless someone messed with them before.

              There are test points on each board for these voltages.

              Match the voltages first with a white wash signal, then if that does not help remember the original position of SET_UP and SET_DN and adjust those two slowly.

              Y and Z boards screws need to be very tight.

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                #8
                Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                Originally posted by Biruslapio View Post
                Could be cracked solder joints on the big inductors on Y and Z SUS boards, or poorly adjusted SET_UP and SET_DN on Y-SUS, there are several trimpots on Y-SUS, Z-SUS and the power supply, they control VS, VA, -VY, VSCAN and Z-BIAS, these voltages should match what the white panel label specifies, you don't need to adjust those unless someone messed with them before.

                There are test points on each board for these voltages.

                Match the voltages first with a white wash signal, then if that does not help remember the original position of SET_UP and SET_DN and adjust those two slowly.

                Y and Z boards screws need to be very tight.
                I did alter the RAMP_UP and RAMP_DN pots. Prior, I did mark their positions with a felt marker so they could be returned to their original positions. Both altered the view, but neither one eliminated the issue.
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                  #9
                  Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                  What about the other voltages that can be adjusted, are they correct? Low VS can cause this type of image retention.

                  This Y-SUS is absolutely blackened in the middle, so much heat that even a capacitor managed to poof, has this board been repaired before? is Z-SUS fine visually?

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                    #10
                    Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                    Does this cap on Topcat's board look bulged to anyone else?
                    Attached Files

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                      #11
                      Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                      It would be worth checking but it may also be the angle.
                      Willing to help but I'm no expert.

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                        #12
                        Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                        Originally posted by tvtimmy View Post
                        Does this cap on Topcat's board look bulged to anyone else?
                        It was, it has been replaced along with all those of that value (100uF 50v). That's why the board was out of the set....recapping and checking for cracked solder under all that heat.
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                          #13
                          Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                          Originally posted by Biruslapio View Post
                          What about the other voltages that can be adjusted, are they correct? Low VS can cause this type of image retention.
                          I kicked up the VS, it went away for the most part. I don't have the service manual, so I was doing this blind based on a white raster until it shut down...then backed it off a little. It is significantly better though, seems you're onto something!
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                            #14
                            Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                            Originally posted by Topcat View Post
                            I kicked up the VS, it went away for the most part. I don't have the service manual, so I was doing this blind based on a white raster until it shut down...then backed it off a little. It is significantly better though, seems you're onto something!
                            Guessing you are aware but just in case - lots of hits over at Elektrotanya for manuals:

                            https://elektrotanya.com/showresult?...a=All&kat2=All

                            I downloaded the top one and it appears to have alignment procedures, although fairly complicated and maybe requiring some special test equipment.
                            Attached Files

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                              #15
                              Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                              LG plasma service manuals are only good for mainboard schematics/diagrams, there's nothing about the other inner workings of a plasma, you will need a LG training manual - scan troubleshooting to get actual material about Y and Z-SUS boards, there's no training manual of PA series available online that I could find.

                              The set shut down because of excessive VS voltage, this is to protect SUS and power supply boards from erratic operation, something is interfering with VS on this TV, may be a cracked soldering joint or more bad capacitors near the area that clearly overheated on the Y-SUS.

                              I've uploaded pictures and circled test points and trimpots that adjust -VY and ZBIAS, can't find VSCAN trimpot, maybe this model doesn't have one. VS is adjusted on the power supply, should be matching the panel sticker. The main filtering inductors on Z and Y are also circled, these need have their contacts properly resoldered to the board, they often crack and introduce pink sparkling on the screen.

                              The panel sticker is an example, voltage ratings varies from model production date etc, the voltages you adjust must match what your panel specifies.
                              Attached Files

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                                #16
                                Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                                ^
                                Thanks for all the info. I do think the coils need to be reflowed, I didn't do them on the zsus board, just the Y...and now & then I do get reddish/pink graininess....which seems to come & go, moreso when its cold....but the ghosting is gone now.

                                I definitely want to tweak it some more, but after the 'seat of my pants' adjusting, it's looking pretty good. I'll get behind it and set it correctly tomorrow....

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                                  #17
                                  Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                                  Originally posted by Biruslapio View Post
                                  LG plasma service manuals are only good for mainboard schematics/diagrams, there's nothing about the other inner workings of a plasma, you will need a LG training manual - scan troubleshooting to get actual material about Y and Z-SUS boards, there's no training manual of PA series available online that I could find.

                                  The set shut down because of excessive VS voltage, this is to protect SUS and power supply boards from erratic operation, something is interfering with VS on this TV, may be a cracked soldering joint or more bad capacitors near the area that clearly overheated on the Y-SUS.

                                  I've uploaded pictures and circled test points and trimpots that adjust -VY and ZBIAS, can't find VSCAN trimpot, maybe this model doesn't have one. VS is adjusted on the power supply, should be matching the panel sticker. The main filtering inductors on Z and Y are also circled, these need have their contacts properly resoldered to the board, they often crack and introduce pink sparkling on the screen.

                                  The panel sticker is an example, voltage ratings varies from model production date etc, the voltages you adjust must match what your panel specifies.
                                  I got them all dialed in except VS. If I set VS at its prescribed voltage (205v), the ghosting & horrible red graininess comes back. Set around 210~212, that clears up, TV runs without issues. It shuts down around 215. VS feeds the ZSUS board, so my guess is whatever issue there is, is on that board. I guess it could be YSUS as well, there's a harness that goes from ZSUS to YSUS right by the feed from the PSU board.

                                  I reflowed all the coils, transistor, higher watt resistors, and anything else that was even remotely questionable.....

                                  The only mystery seems to be why the VS at normal setting yields a grainy/ghosty image.....makes me wonder if some of these higher voltage lytics have failed as well, as hot as this thing runs.... Heat and lytics aren't friends.
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                                    #18
                                    Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                                    There is nothing wrong with upping the VS a few volts, The LG tech even recommended it when these were a couple years old. The panel will change over time. It is also possible there is a control board firmware update, I know they had it for certain models, but they were the earlier models.
                                    Last edited by R_J; 05-10-2021, 06:39 PM.

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                                      #19
                                      Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                                      Originally posted by R_J View Post
                                      There is nothing wrong with upping the VS a few volts, The LG tech even recommended it when these were a couple years old. The panel will change over time. It is also possible there is a control board firmware update, I know they had it for certain models, but they were the earlier models.
                                      I did find a firmware dated 2013 on LG's site, the set was made Jan 2012...and I doubt the owner ever updated it. I'll do the update of course....but I don't think it'll help much unless it kicks up the VS shutdown voltage.... I see the issue potentially being more of a degraded panel perhaps....given the visible sign of heat on both YSUS and ZSUS boards, the set likely has a lot of hours on it....I've probably got it about as good as it's going to get....but overall I'm happy, perfectly watchable and my first ever battle with a plasma.

                                      One thing I couldn't find were the RAMP_UP & RAMP_DN threshold/voltages & testpoints...maybe they're not important....but I was curious.
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                                        #20
                                        Re: fixed but got grainy/noise picture on my plasma now -LG 50PA6500

                                        The connection going from Ysus to Zsus is probably the 15v line. It's generated on the Ysus, sometimes routed through the control board. Probably not an issue.

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