LG 60PK950 - multiple issues, chain of events

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  • cybericius
    Member
    • Mar 2016
    • 15
    • Hungary

    #1

    LG 60PK950 - multiple issues, chain of events

    Hi All,

    I have the TV mentioned in the subject.

    Couple of months ago, it started to show green vertical lines, appearing in the same positions. There were only one or two at the beginning, then it started to grow to around the amount of 10. All of them were in the middle third segment.

    Then recently, we decided to paint the living room, so I removed the TV from the mount and disassembled it. Before doing this, I downloaded some materials about the connections, panels, troubleshooting of this specific model family (60PK<x>) to get aligned in the topic.

    Let me drive you through the steps of troubleshooting and getting deeper in the mud:

    1. Center X-Board (EBR63451301) and Control Board (EBR63450301) connection cleaning and reseating.

    2. Turning the TV on: for couple of minutes the mentioned green lines were still spotted at the same locations, then a sudden, silent pop from somewhere around between the mid and top section of the TV. Result: no middle third vertical part = pitch black. Swearing...

    3. Some more troubleshooting guide I downloaded. Reading, learning. Got to the conclusion that either the center X-Board or the Control Board went out.
    I connected the P104 tape connector to P102 to check if the center controller would do anything to the right X-Board and I saw some white garbage on the screen. This is why I supposed that it might not be the Control Board that was faulty, but the center X-Board, as it feeds something from P102 at least.

    4. I found a center X-Board on ebay, so I took my chance. Couple of weeks of waiting, happiness after receiving the package, then very sad face when I realized that it had not helped at all.

    5. More troubleshooting with multi-meter. X-Board voltages are fine (both 60V coming from the Y-SUS (P114 connector -> P220 -> P320) and 3.3V RGB signals coming from the Control Board (P102 -> P210).

    6. Then I decided to check the Control Board, as that was indicated in the troubleshooting documentation as a second possible candidate. I removed the LVDS cable and tried the test mode by shorting the AUTO GEN pins. Same issue, but the test mode was working properly. Control Board voltages, resistance seemed also to be fine, 3.3V, 5.1V etc. Whatever should have been measured were fine, even the P102 and P210 pins had the 3.3V. Green LED properly producing an irregular, but firm blinking. Then, I did a big mistake, I don't know for sure what the mistake was, but I changed the meter to Hz mode to check the oscillator whether it was really 25MHz or not. This move turned the TV off after hearing a similar, not so loud popping sound from the top-right section of the TV.

    7. After some search, I figured out that the FS103 fuse (6.3A/250V) - protecting the VS line - got broken on the Z-SUS Board (EBR63450501). Hair pulling. Bigger buzzing noise from the SMPS while the TV was turned on and low intensity issue was observed. BTW, before this, I got some measurements on this board, and seemed like to be fine. 104.9V was measured on VZB after 2 minutes heating (was 99V at initial switch on), I think it was fine, as has to be 105V. I successfully ruined it.

    8. I put in a new fuse, hoping for that only the fuse got bad and only due to the oscillator measurement. No success, could not get back to at least the original middle vertical black bar symptom. The TV switches off after hearing the first relay click, going back to stand-by.

    9. If I remove the P102 connector (SMPS->Z-SUS power connector), then the TV turns on and has the left/right thirds working (still middle black bar issue), but of course the intensity is very low, the picture can be hardly seen.
    Voltages are fine on P811 (SMPS).

    ---------------------

    This is where I am now.

    Questions:

    Can I assume that the SMPS is still working properly (right measurements on P102) and I have now issue with at least the Z-SUS board (EBR63450501)?

    What would you check on the Z-SUS? Visually it looks good, no popped/leaking capacitors, no other issues.

    If I could manage to repair/replace the Z-SUS, expecting that it is the culprit now, what could be causing the middle third black vertical bar?
    Last edited by cybericius; 03-14-2016, 02:27 PM.
  • cybericius
    Member
    • Mar 2016
    • 15
    • Hungary

    #2
    Re: LG 60PK950 - multiple issues, chain of events

    All the documents I could find as references.
    Attached Files
    Last edited by cybericius; 03-14-2016, 02:10 PM.

    Comment

    • cybericius
      Member
      • Mar 2016
      • 15
      • Hungary

      #3
      Re: LG 60PK950 - multiple issues, chain of events

      Thank you very much in advance for any help.

      Comment

      • cybericius
        Member
        • Mar 2016
        • 15
        • Hungary

        #4
        Re: LG 60PK950 - multiple issues, chain of events

        Can anyone suggest some troubleshooting method?
        Should I look for open or short circuit elements on the Z-SUS?
        Thanks.

        Z-SUS is removed. Multi-meter is set to Ohm mode.
        If I put the negative tester to one of the GND pins of the P102 connector and scan with the positive tester on other parts, then it seems like that though the HS203 segment of MOSFET's are showing low resistance, the HS204 segment MOSFET's show open circuit.
        Last edited by cybericius; 03-15-2016, 08:32 AM.

        Comment

        • cybericius
          Member
          • Mar 2016
          • 15
          • Hungary

          #5
          Re: LG 60PK950 - multiple issues, chain of events

          I have tested the MOSFETs and though the legs show different resistance on some, they behave the same.

          Comment

          • mmartell
            Badcaps Legend
            • Oct 2013
            • 3189
            • Canada

            #6
            Re: LG 60PK950 - multiple issues, chain of events

            Picture of the fault would be helpful but it sounds to me that the cof for that part of the screen has shorted. If that's the case it is unrepairable.

            Comment

            • cybericius
              Member
              • Mar 2016
              • 15
              • Hungary

              #7
              Re: LG 60PK950 - multiple issues, chain of events

              Originally posted by mmartell
              Picture of the fault would be helpful but it sounds to me that the cof for that part of the screen has shorted. If that's the case it is unrepairable.
              Hi Mmartell,

              Thanks for taking your time helping me.
              Not much to photo now, it is totally blank now due to - most probably - the Z-SUS issue.

              I anyway attach some simulated scenarios how the problem got deeper during troubleshooting.

              Step1: some green vertical lines were present in the middle third segment.
              Step2: the middle third segment went out totally.
              Step3: simulated symptom when Z-SUS is removed.
              Step4: total blackness, TV turns off after one relay click sound, going back to stand-by when Z-SUS is attached.

              Do you mean by COF the chip which is integrated into the ribbon cables that are part of the plasma display and are connected to the X-Board?
              I suppose this assumption could be valid for all the cases, except for the last one. Though I think if only one COF goes wild, then not the whole third of the screen in the middle would be affected, but only some limited the ratio of the screen which is controlled by one COF. Of course, if all the COFs are out going to the center X-Board, then this case can be valid for Step2/Step3.
              Attached Files
              Last edited by cybericius; 03-18-2016, 07:45 AM.

              Comment

              • cybericius
                Member
                • Mar 2016
                • 15
                • Hungary

                #8
                Re: LG 60PK950 - multiple issues, chain of events

                Attaching the center X-Board (EBR63451301) picture.
                Attached Files

                Comment

                • mmartell
                  Badcaps Legend
                  • Oct 2013
                  • 3189
                  • Canada

                  #9
                  Re: LG 60PK950 - multiple issues, chain of events

                  Why wouldn't it be valid for step 4 ? Though I admit it's odd for the whole third of the screen to be out, that points to an x board failure which you've replaced. I suppose thw control board could have failed but that's a new failure mode on me for a control board.

                  Comment

                  • cybericius
                    Member
                    • Mar 2016
                    • 15
                    • Hungary

                    #10
                    Re: LG 60PK950 - multiple issues, chain of events

                    Originally posted by mmartell
                    Why wouldn't it be valid for step 4 ? Though I admit it's odd for the whole third of the screen to be out, that points to an x board failure which you've replaced. I suppose thw control board could have failed but that's a new failure mode on me for a control board.
                    That is step 2 or/and 3. Step 4 is I think because of Z-Sustain. If I remove it (step 3), then the TV still turns on, but with black bar and low intensity issue.

                    Do you think half/third black screens are rarely caused because of malfunctioning control boards? Honestly, really strange, since the voltages are fine on the new X Board, too, coming from both the Y-Sustain Board (60V) and Control Board (3.3V). The worst thing I can suspect is that all of the 7 COF chips have been damaged due to some earlier shorted circuit.

                    Could it be the case that when I cleaned the COF cable pins with alcohol, I was not waiting enough time for them to dry?

                    Could it be something else? E.g. no power comes from somewhere else to drive that part?

                    In the meantime I managed to order some used parts (both Control Board and Z-Sustain Board) from ebay. I will replace them both at the same time to avoid damage caused to a good new one by a possible faulty element.

                    So, hopefully, we will see the answer in a week.

                    Thanks for the help.
                    Last edited by cybericius; 03-19-2016, 04:43 PM.

                    Comment

                    • mmartell
                      Badcaps Legend
                      • Oct 2013
                      • 3189
                      • Canada

                      #11
                      Re: LG 60PK950 - multiple issues, chain of events

                      Yes it's possible to damage a cof with a residual charge and even more likely to destroy it with power applied. However I've not heard anyone say they've destroyed that many in one go, especially contained to those of a single board.

                      Are these x boards daisy-chained ?

                      Comment

                      • cybericius
                        Member
                        • Mar 2016
                        • 15
                        • Hungary

                        #12
                        Re: LG 60PK950 - multiple issues, chain of events

                        Originally posted by mmartell
                        Yes it's possible to damage a cof with a residual charge and even more likely to destroy it with power applied. However I've not heard anyone say they've destroyed that many in one go, especially contained to those of a single board.

                        Are these x boards daisy-chained ?
                        I have attached the connection figure of the X boards.
                        Attached Files

                        Comment

                        • Alastair E
                          Chief Womble
                          • Mar 2013
                          • 1963
                          • U.K.

                          #13
                          Re: LG 60PK950 - multiple issues, chain of events

                          COF chips VERY easy to damage.

                          From description of events--They are toast!

                          A surge or poor supply connection can easily kill multiple COF. I proved this on a buggered samsung panel for research (larf) ...

                          Don't waste any more time or dosh on this set--Its gone...
                          TELEFIX

                          How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                          http://www.irf.com/technical-info/appnotes/an-1088.pdf
                          PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                          Comment

                          • cybericius
                            Member
                            • Mar 2016
                            • 15
                            • Hungary

                            #14
                            Re: LG 60PK950 - multiple issues, chain of events

                            Originally posted by Alastair E
                            A surge or poor supply connection can easily kill multiple COF. I proved this on a buggered samsung panel for research (larf) ...
                            Alastair E, do you have a link or reference of this research, by the way?
                            Thanks for the tips so far.

                            I will post the result when I get the replacement boards and could check them. I have almost zero hope after the comments.

                            Comment

                            • cybericius
                              Member
                              • Mar 2016
                              • 15
                              • Hungary

                              #15
                              Re: LG 60PK950 - multiple issues, chain of events

                              Alright, I have received the replacement boards.

                              One of them is good (Z-SUS), working properly. Check.

                              The other one is bad (Control Board) as a chipped 4R7 S1 device can already be identified visually and if I put it in, then there is only blank screen, at least does not go back to stand-by mode. So I am still using my original Control Board.

                              Now I have screen, but still only on the left and right sides.

                              Attaching some pictures.

                              Replacement for the control board will be sent again.
                              Attached Files
                              Last edited by cybericius; 04-10-2016, 08:12 AM.

                              Comment

                              • Redjess
                                Senior Member
                                • Feb 2016
                                • 54
                                • Usa

                                #16
                                Re: LG 60PK950 - multiple issues, chain of events

                                On my 60pk550, im fairly certain I fried the cof, i get blank vertical strips too, but it lights up and theres a sqiggly line in motion thru them. On one side only too.

                                Comment

                                • cybericius
                                  Member
                                  • Mar 2016
                                  • 15
                                  • Hungary

                                  #17
                                  Re: LG 60PK950 - multiple issues, chain of events

                                  Okay, this is the COF, now I am certain.
                                  After leaving the TV on for couple of minutes, I noticed a new green vertical line now belonging to the right X buffer segment. While I was inspecting it and the movie scene changed to almost all white, then the left X buffer part COF's gave some bursts and two smaller vertical black stripes appeared. I turned the TV off, but with an immediate realization of that my adventure with my beloved TV has just been over.
                                  Now I am thinking about how to do the burial ceremony.
                                  Thanks, guys, for the help anyway, it was a pleasure to learn from such experts! Good luck in life!

                                  BTW, any good suggestion on a relatively cheaper, 60-65 inch LED, no 3D, not necessarily SMART, no tuner, >1 HDMI, no curve, no flashy stuff, but excellent picture quality (still, motion, no artifacts). I would use it for my PC. Thanks.
                                  Last edited by cybericius; 04-12-2016, 02:30 PM.

                                  Comment

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