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LG 50PX950 Clicks, Turns off instantly

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    LG 50PX950 Clicks, Turns off instantly

    Hello all and thanks for having such an amazing forum! I was searching for how to fix my tv and this forum kept coming up so I thought I'd ask you guys now that I've done a little bit of research and digging around.

    I looked at this thread https://www.badcaps.net/forum/showth...50PK350&page=2 as it was the closest I could find to relating to my tv, but it's not the exact situation that I had. Here is what happened:

    I sat down to watch TV like normal and I turned it on. It came on with no issues and I used it for ~1 minute and then it turned off. When I tried to turn it back on, it continued to do the same thing over and over; click, show the white light on the bottom center, then quickly click off back to standby. I left it overnight and it never stopped doing this. So I took off the back and started trying things.

    Unplug the zboard and when I plug it in, it turns on instantly and shows a distorted version of the "input status" in the top left, but no color or anything like that. I try a few different menu options and it appears to respond (the distorted shape changes on the screen). Also, when I unplug it, the red "standby" light stays on for at least 2-3 minutes. Me being the noob I am, unplugged it thinking there was no more power, tried to plug in the zboard again, and saw a quick spark where the pins met the connector. Hopefully this didn't do any harm...

    Unplug the yboard and it turns on but shows nothing, no backlight or anything.

    Plug both back in, turn on the tv and... walla, it turns on with no issues. Now that I have the back off and everything, I really want to fix what's broken before I put it back together.

    Unfortunately, I thought I had a multimeter but I do not know where it went. As it stands, I really just want to replace a whole board or send it in to get it repaired. I have no problem buying a new board for 50-70 (ebay) or getting it fixed for the same price, I just want to make sure I am getting the correct thing replaced.

    What else should I unplug and/or test or can you guys give me a definitive answer just from what I have already? Thanks again!
    Last edited by makowb; 07-30-2013, 06:56 PM.

    #2
    Re: LG 50PX950 Clicks, Turns off instantly

    Is the TV now working for an extended period of time without shutting off (e.g. several hours)? I'd look over the power supply and the sustains with a flashlight to eliminate the possibility of cracked solder joints. You could also just have had a bad connection.

    Edit: I've experienced the spark when plugging in sustains. I usually let the TV sit for about 5-10 mins. If I'm in a hurry or I'm unsure about whether a board has discharged (I've also seen a spark when connecting a Y-buffer to a Y-Sus), I use a multimeter to check the voltage at the connector and possibly discharge caps manually.
    Last edited by capkid; 07-30-2013, 07:18 PM.
    LG Plasma Mal-Discharge Correction Service

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      #3
      Re: LG 50PX950 Clicks, Turns off instantly

      So, just tested out the tv with my xbox for about 5-10 minutes max before it turned off, same as before, just shut off.

      To inspect the solder joints don't I need to take off the power supply and flip it over? It looks like all of the connectors are soldered on the other side of the board.

      Anyways, it seems like it could be the power supply but I'm not sure. Anything else I should look for?

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        #4
        Re: LG 50PX950 Clicks, Turns off instantly

        Yes, you'd need to remove the power supply and the sustains to check each (power supply is the likely suspect). Look for anything out of the ordinary (burns, cracked joints, etc). While you're at it, pics would be great so that we can see the circuit board layout. Also, if these visual checks yield nothing, you're going to need a digital multimeter - a cheap one will do.
        Last edited by capkid; 07-30-2013, 08:12 PM.
        LG Plasma Mal-Discharge Correction Service

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          #5
          Re: LG 50PX950 Clicks, Turns off instantly

          As the thread to which you linked points out, it's common for the PSU in this TV to fail. Here are a bunch of repair kits, but I'd still test before installing a kit:

          http://www.ebay.com/sch/i.html?_odkw...r+kit&_sacat=0
          LG Plasma Mal-Discharge Correction Service

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            #6
            Re: LG 50PX950 Clicks, Turns off instantly

            Thanks for the help. I'm gonna update this thread tomorrow evening with my findings. I'm having a buddy bring over a multimeter and I'll write down the numbers and do a visual inspection and try and take some pics.

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              #7
              Re: LG 50PX950 Clicks, Turns off instantly

              Just thought I'd update this by saying that I am too busy this month and have just put the tv to the side to try and figure out later. I will return though!

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                #8
                Re: LG 50PX950 Clicks, Turns off instantly

                Hi there,
                Sorry for hijacking this thread but i have the same TV, LG 50PX950 and similar problem - when i turn it on, it clicks once and the TV screen changes shade from dark black to somewhat grey-er color which indicates something is working, but never shows any picture/menus, etc.
                I did some research and bought the repair kit from Bafury, referenced in the other thread cited here. I started working on the power supply and per the kit's instructions, replaced the 3 resistors, and it is still not working. I disconnected one end of the diode and measured it and it checks out ok, the fuses are also ok. So now i wonder if the voltage regulator works... How can i check/measure it to see if it works? I measured the voltages in the bottom right connector and the 17v/5v/stand by check out fine. The AC detect measures ~3.2v - is this how much it is supposed to be? IS there anything else i need to check?
                Any help is appreciated!

                thanks,

                hehehh
                Attached Files

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                  #9
                  Re: LG 50PX950 Clicks, Turns off instantly

                  Originally posted by hehehh View Post
                  Hi there,
                  Sorry for hijacking this thread but i have the same TV, LG 50PX950 and similar problem - when i turn it on, it clicks once and the TV screen changes shade from dark black to somewhat grey-er color which indicates something is working, but never shows any picture/menus, etc.
                  I did some research and bought the repair kit from Bafury, referenced in the other thread cited here. I started working on the power supply and per the kit's instructions, replaced the 3 resistors, and it is still not working. I disconnected one end of the diode and measured it and it checks out ok, the fuses are also ok. So now i wonder if the voltage regulator works... How can i check/measure it to see if it works? I measured the voltages in the bottom right connector and the 17v/5v/stand by check out fine. The AC detect measures ~3.2v - is this how much it is supposed to be? IS there anything else i need to check?
                  Any help is appreciated!

                  thanks,

                  hehehh
                  According to Tom's post here, your AC detect measurement seems correct: https://www.badcaps.net/forum/showpo...2&postcount=12

                  Did you check your panel voltages?

                  - PSU output: VS and VA
                  - On Y-Sus: -Vy and VSC
                  - On Z-Sustain: Vzb
                  LG Plasma Mal-Discharge Correction Service

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                    #10
                    Re: LG 50PX950 Clicks, Turns off instantly

                    Ok now, on the PSU outputs, the VA is 60v and the VS is 201v.
                    on the Z - VZB1 is 2.79v and vzb2 is zero.
                    on the Y - i have 3 Vy pins, all show 18.47v, i could not see a VSC, where should that be?

                    thanks

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                      #11
                      Re: LG 50PX950 Clicks, Turns off instantly

                      Are you measuring -Vy across the indicated resistor?

                      PDP50xxxxx number written on "LG ELECTRONICS" panel sticker could be useful for finding panel information.
                      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.

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                        #12
                        Re: LG 50PX950 Clicks, Turns off instantly

                        no, i measured the vy on the pins of the ribon connector at right side of the Y board - is that not the appropriate place? These pins are pretty small and it is a bit hard but i tried it several times and the measurements were consistent.
                        Thank you tom66 and capkid for the help!

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                          #13
                          Re: LG 50PX950 Clicks, Turns off instantly

                          Can you get the PDP50xxxxxx number of the panel sticker so I can look up where to test?
                          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


                            #14
                            Re: LG 50PX950 Clicks, Turns off instantly

                            I am not at home, but based on the the attached pic it is PDP50R10333 (it is a little ineligible, but seems that is the number).
                            Based on the second pic, it seems the voltages check out, other than Vy which is not listed...
                            Attached Files

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                              #15
                              Re: LG 50PX950 Clicks, Turns off instantly

                              Great, see this guide for info


                              (Search for 50R1)
                              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


                                #16
                                Re: LG 50PX950 Clicks, Turns off instantly

                                Wow, this is very helpful - thanks! Looks like i will need to measure the VSC and -Vy at the resistors - i will do that tonight and report back. A couple of questions for the test:
                                -the manual says to place the unit in "white wash" - what is that?
                                -there is a section that describes waveform test/adjustments - is that something i should do and can i do it with just a multimeter?
                                -and lastly, it seems that the VA is up to spec and the Vs is 201 while the specs says 203v - should i bother to adjust this or the diff is too small to matter?

                                Thanks for all the help and info!

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                                  #17
                                  Re: LG 50PX950 Clicks, Turns off instantly

                                  You won't be able to do white wash without powering the set up, but for now that isn't critical. Just see if you get anything on -Vy/Vsc.

                                  The panel label should always be followed. Do not follow what the manual says as that is an example, every plasma panel can be slightly different from every other panel. I wouldn't worry about 201V vs 203V either.
                                  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


                                    #18
                                    Re: LG 50PX950 Clicks, Turns off instantly

                                    Thanks tom66, i appreciate your help! I will measure tonight and report back.

                                    Comment


                                      #19
                                      Re: LG 50PX950 Clicks, Turns off instantly

                                      Updated measurements:
                                      on the PSU: VS=201.7 va=60
                                      On the Y : Vy is 189.7 and VSC=149.7
                                      On the Z board, the VZB is 109.7.
                                      So, all is very much up to spec... What should be the next step in the troubleshooting process?

                                      thanks,

                                      Comment


                                        #20
                                        Re: LG 50PX950 Clicks, Turns off instantly

                                        Do you have sound?
                                        LG Plasma Mal-Discharge Correction Service

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