LG Plasma 50PC1DR- Y-SUS Issues

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  • tw2005
    Badcaps Legend
    • Oct 2011
    • 6458
    • Australia

    #61
    Re: LG Plasma 50PC1DR- Y-SUS Issues

    I know on the ZSUS we kept smoking the same R100 resistors on it but I believe it was the bad YSUS (J015 module shorted) that may have been causing that. Replaced them with 1 watt metal film conventional resistors. Smoked them a bit more but then replaced the YSUS and now that ZSUS is working fine?

    Could it be a bad ZSUS doing the same to your YSUS? Just a guess.

    Comment

    • tw2005
      Badcaps Legend
      • Oct 2011
      • 6458
      • Australia

      #62
      Re: LG Plasma 50PC1DR- Y-SUS Issues

      Originally posted by cheebster
      Okay. They are a little bigger, they seem to be 2512;

      0.248" L x 0.126" W (6.30mm x 3.20mm)

      I just have a ruler though. Is 1W sufficient for this size ?

      I'm still trying to find out what's shorting the 120VDC vsc after the sub board. from what i understand, this is being sent directly to the y-drive output?

      I see Q2, Q3 there, also Q13, 05 (can't find this Q05?).. all seem fine

      I'm trying to figure out what's a 4A67 diode and a 25 diode. Google results are a *bit* confusing to me !

      I'd really like to find out what's draining the vsc down from the sub-board that generates VSC. i see VS coming in, VSC going out, then if i check output at the VSC test points it's 0-10 volts. I don't understand !!!
      I think it's D5, next to Q13
      Attached Files

      Comment

      • cheebster
        Badcaps Veteran
        • May 2008
        • 374

        #63
        Re: LG Plasma 50PC1DR- Y-SUS Issues

        tw2005, yea that's what i think as well about the bad ipm.. also think that !!!

        i'm getting some new ipm's today here. just a little fear of smoking the ipm's if i install them on the boards right now ?

        i just wanna make sure i got no other issues before i try them on, they seem fragile..

        can a bad yppd j015 drive vsc down to 0v ?

        i've tried 3 different zsus and the issue was the same. so i'm ruling zsus out..
        Last edited by cheebster; 09-18-2012, 07:49 AM.

        Comment

        • tw2005
          Badcaps Legend
          • Oct 2011
          • 6458
          • Australia

          #64
          Re: LG Plasma 50PC1DR- Y-SUS Issues

          Could it be a 4A and those other numbers are date code or batch. I have a bunch of 4A and below I can just make out actually 3 digits. mine are 541 on the 2005 board, 751 on the 2006 board.
          Attached Files

          Comment

          • tw2005
            Badcaps Legend
            • Oct 2011
            • 6458
            • Australia

            #65
            Re: LG Plasma 50PC1DR- Y-SUS Issues

            Originally posted by cheebster
            tw2005, yea that's what i think as well about the bad ysus.. also think that !!!

            i'm getting some new ipm's today here. just a little fear of smoking the ipm's if i install them on the boards right now ?

            i just wanna make sure i got no other issues before i try them on, they seem fragile..

            can a bad yppd j015 drive vsc down to 0v ?

            i've tried 3 different zsus and the issue was the same. so i'm ruling zsus out..
            no idea, I think you know more than me on this. I have a j015 coming for this and hope I don't smoke it. If I do I'll live with one good set but I know this ysus was ok until the guy shorted it and blew his ipm again.

            If you saw the state of the Z I got after he was finished you'd think that was a goner too but fluked that one back to life.
            Last edited by tw2005; 09-18-2012, 07:54 AM.

            Comment

            • tw2005
              Badcaps Legend
              • Oct 2011
              • 6458
              • Australia

              #66
              Re: LG Plasma 50PC1DR- Y-SUS Issues

              where's the "25" diode? I having to guess what bits you are looking at. Can you give location numbers?

              hope your buffers are good, they are a known working set your using?

              It's late here.
              Last edited by tw2005; 09-18-2012, 08:12 AM.

              Comment

              • cheebster
                Badcaps Veteran
                • May 2008
                • 374

                #67
                Re: LG Plasma 50PC1DR- Y-SUS Issues

                the buffers are good i think. the resistance measurements seem to be OK;
                i don't know how to check them more than doing resistance checks on the plates connecting to the ysus and doing the fets on diode check mode.. the buffer ic's look visually OK. tried swapping them a lot as well, no dice.

                the 25 diode is located at D32 the small diode there

                https://www.badcaps.net/forum/attach...8&d=1347410753

                under the right black heatsink ramp_up over the cap.

                Comment

                • cheebster
                  Badcaps Veteran
                  • May 2008
                  • 374

                  #68
                  Re: LG Plasma 50PC1DR- Y-SUS Issues

                  tw2005, if you ever have 200$ loose, get an hakko 808. this is a GREAT tool, incredible. made in japan, it's a desoldering gun.. it takes 2-3 minutes to remove a ipm with one of these. i wish i purchased this thing way before.

                  Comment

                  • cheebster
                    Badcaps Veteran
                    • May 2008
                    • 374

                    #69
                    Re: LG Plasma 50PC1DR- Y-SUS Issues

                    SAY WHAT ? oh yeah, fixed my first plasma ever. turns out the IPM was sucking the vsc down.. new J015, and bam ! a working plasma. god im happy, not that i needed the tv.. just the fact that it works !!!!

                    Comment

                    • cheebster
                      Badcaps Veteran
                      • May 2008
                      • 374

                      #70
                      Re: LG Plasma 50PC1DR- Y-SUS Issues

                      um.. the tv shuts down after a few seconds. the screen looks perfect, but it shuts down still. it's on the tuner input..

                      i messed a lot with the pots on that board. -yv seems ok 196v, vsc 115v ok, but the ramp_up, ramp_down and set_up pots, ive messed with them as well. how can i adjust those ?

                      Comment

                      • tom66
                        EVs Rule
                        • Apr 2011
                        • 32560
                        • UK

                        #71
                        Re: LG Plasma 50PC1DR- Y-SUS Issues

                        You need a scope to adjust them but they will only affect the picture, and it shouldn't shut down if they are wrong. You can usually tweak them enough to get an acceptable picture. You can however check Vs, Va and the logic/signal board supplies - 6V, 19V etc.

                        N.B. On mine I also had ac line detection issues, you may have the same problem. Check the 50PQ3000 thread.

                        Very surprising IPM was loading down Vsc. Oh how glad I am that IPMs are not used in newer sets. Discrete FTW!
                        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

                        • cheebster
                          Badcaps Veteran
                          • May 2008
                          • 374

                          #72
                          Re: LG Plasma 50PC1DR- Y-SUS Issues

                          i got some used ipm's from utsource on aliexpress. 2X.xx for shipping but was 3 days delivery.. they are sanyo's. can we mix and match the lg and sanyo ipm's ? i got 2 diff. brands on my board here. the snow picture looks fine, ive tested many diff. settings on the pot and it didn't affect the behavior, always shuts down. UM.

                          what is the ac line detection issue ?

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #73
                            Re: LG Plasma 50PC1DR- Y-SUS Issues

                            It is to do with a design fault in the LG PSU. There is a pin on the PSU marked AC-DET. Check it is stable 5V. If not, you have the AC-DET fault which is usually an easy fix.

                            Try with a dimmer picture. May be a cold joint. Check if Vs drops out or stays.
                            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

                            • cheebster
                              Badcaps Veteran
                              • May 2008
                              • 374

                              #74
                              Re: LG Plasma 50PC1DR- Y-SUS Issues

                              how can i dim the picture, lower the VS ?

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #75
                                Re: LG Plasma 50PC1DR- Y-SUS Issues

                                No... watch something dimmer . Like switch it to a video input and play a DVD.
                                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

                                • cheebster
                                  Badcaps Veteran
                                  • May 2008
                                  • 374

                                  #76
                                  Re: LG Plasma 50PC1DR- Y-SUS Issues

                                  hehe it was shutting down too quick.

                                  you know what can make a plasma like this shut down also?

                                  THE FAN ! hehe. i just noticed this one had a spare fan connector.. an no fan ! i took a fan from another set and hooked it up, bingo.

                                  never noticed it til now. so set is working now, no shut down.

                                  Comment

                                  • tom66
                                    EVs Rule
                                    • Apr 2011
                                    • 32560
                                    • UK

                                    #77
                                    Re: LG Plasma 50PC1DR- Y-SUS Issues

                                    Brilliant to hear you fixed it! But I do hate the LG's with fans, they are poorly implemented. I had one which was chock full of cigarette smoke dust - the kind of sticky stuff that gets everywhere and makes it smell like an old bar. It almost blew up a MOSFET, as there was a nice arc from it when it powered up after retrieving it from the dump.

                                    Panasonic plasma with fan, that is different. I think they use some kind of filter or special design, because there's usually only a small amount of dust which doesn't pose a problem.

                                    If you want to repair plasmas, your next investment should be a scope.
                                    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

                                    • cheebster
                                      Badcaps Veteran
                                      • May 2008
                                      • 374

                                      #78
                                      Re: LG Plasma 50PC1DR- Y-SUS Issues

                                      Yeah, well i loved playing with these. I got customers waiting a bit on me tho, im an it guy and im the passionate type, i usually not give up until i fix the thing..

                                      sometimes takes too much of my time, but hell it's rewarding when it works. now i got 1 working tv.. but 2 others not fixed yet, and a 42 inch of similar design to go.

                                      did you see that link i showed to the rigol one ?

                                      http://www.amazon.com/Rigol-DS1052E-...=rigol+ds1052e

                                      can be hacked into a 100mhz one.. that one seems a good one for the price.

                                      im loving my multimeter so far, its a fluke 115. works so much better than generic one i had...

                                      should i add fans to the ipm's on the plasma ?

                                      Comment

                                      • tom66
                                        EVs Rule
                                        • Apr 2011
                                        • 32560
                                        • UK

                                        #79
                                        Re: LG Plasma 50PC1DR- Y-SUS Issues

                                        Add fans only in the places where dust won't pose too much of a problem; these TVs are not designed to have fans in most cases, so finding space could be tricky. Making sure the vents are clean should give it a 5-10 year service life, but LG designed these poorly, they run very hot and cook the IPMs.

                                        The DS1052E is a fine scope. I have the genuine DS1102E 100 MHz version which only costs $70 extra nowadays - TBH, the risk of bricking a $350 scope to upgrade the bandwidth isn't worth it for me, as a poor student. Besides, 50 MHz is fine for all plasmas up to and including 1080p ones. You'll also need a -fixed- 10X 600V CAT-III probe - NOT the ones supplied in the package, as they are only 300V rated and plasmas can use up to 400V peak sustain waveforms. The scope can handle 300V on 1X, but in theory up to the probe's rating, or 3kV (whichever is lesser) on 10X.

                                        It's very important that it is fixed. If you set the probe wrong, the front end of the scope could be damaged.

                                        If you use the advanced trigger functionality, it's possible to get a rock solid trigger on the sustain waveform, allowing you to check things like the ramp_up and ramp_down timing, as well as the sustain voltages. The pulse width and slope triggers are very useful. It's also possible to see weak sustain voltages or in some cases wounded IPM waveforms which disagree with the SM.
                                        Last edited by tom66; 09-18-2012, 01:37 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

                                        • cheebster
                                          Badcaps Veteran
                                          • May 2008
                                          • 374

                                          #80
                                          Re: LG Plasma 50PC1DR- Y-SUS Issues

                                          Okay, that might be my next investment...

                                          So now im checking the second set.

                                          PSU seems ok, no bulged caps. VS is OK, VSC OK, -YV OK, voltages all good.
                                          I get audio, but screen does fire up. I've replaced j016 on that board with a sanyo IPM as well.

                                          If i check voltage at the ysus buffer boards, there i see fluctuation of voltage between 75 and 85 vdc and following the 4th led on the main board there.

                                          when the 4th led flickers quicker the voltage changes goes a bit higher.. it seems to be trying to fire up the display but fails.

                                          the ER ipms j016's run hotter than the SUS 015 ones, that seems to be normal

                                          However, no screen Any pointers ? tom66, if you ever come to montreal, i owe you a few beers...

                                          Comment

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