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LG EAY60968801 Power Supply Unit(Plasma 50pk series)

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    LG EAY60968801 Power Supply Unit(Plasma 50pk series)

    LG EAY60968801 Power Supply Unit

    There's heaps of threads on these type of PSU including other variants all with similar issues.

    I've tried looking for similar threads to mine but never see a fix. If you've got the common failure of open cct resistors or bad IC you're laughing.

    I also have the HD model PSU LG EAY60968701 Power Supply Unit which was running fine until I started borrowing parts and poking around and it too has the exact same symptoms, so I've spiked something but can't find it.

    Here's what I can tell you based on EAY60968801 .
    Firstly I've set it up for testing minus a load which is not an issue for what I want to do.

    Apply power, 2 relay clicks

    Stdby, M17V , M5v are good, ACDET is good, Error DET is good

    No Va, or VS

    Relays unlatch, denergises, pause then repeat 2 clicks , reading s as above and continually does this.

    If it's fitted, 3 of these cycles then quits. Assume the mainboard says enough is enough and stops the cycle.

    No open cct high wattage resistors
    No shorted ICs or Transistors evident
    Resistor network commonly identified as faulty good and even rebuilt
    All solders are good
    all transformers good
    No obvious shorted diodes, ZD301 was damaged through the fault finding and went short , replaced

    Micro controller, IBR chip, two driver ICs, and optos all swapped out and fitted to another working board, confirmed all good.

    Surface resitors appear ok, have compared measurements to good board and seem comparable.


    have tried using Paulsetf's cct diagram but stumped.

    There are a number of surface transistors with inbuilt resistors, not sure how you know if they're bad

    Images are stock images hoping someone can work out the cct
    Attached Files

    #2
    Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

    What are you trying to do
    Is the power supply not producing power ??
    I suspect you have a main board fault that is not turning on the power board

    Comment


      #3
      Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

      Yes. The PSU seems to be OK since it is producing the Std-by, 17V and 5V voltages. There are fuses on the Y-SUS and X-SUS boards, check and verify they are good. If these are OK I will have to agree with chrismurphy that the Main Bd is the culprit.

      Comment


        #4
        Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

        Originally posted by chrismurphy View Post
        What are you trying to do
        Is the power supply not producing power ??
        I suspect you have a main board fault that is not turning on the power board
        Originally posted by Andrew F. Ali View Post
        Yes. The PSU seems to be OK since it is producing the Std-by, 17V and 5V voltages. There are fuses on the Y-SUS and X-SUS boards, check and verify they are good. If these are OK I will have to agree with chrismurphy that the Main Bd is the culprit.
        It's a lot of info to chew so I'll try and clarify.

        Firstly, 100% not main.

        I have another working PS to compare too.

        It's out of the TV and jumpered for testing.

        all voltages are good but no Va, VS being produced

        All fuses are good

        390V is available

        The TV works with a working PSU.

        M5V comes on when the relays latch, then goes when they unlatch (normal)
        Last edited by tw2005; 11-02-2017, 11:14 AM.

        Comment


          #5
          Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

          Hi TW how are you jumping the supply,you need to first jump auto ground to ground with mains power to the board you should see 3.5v at P813, then jump RL on to standby (make high), both relays should come in and give you the 5v and 17v rails,to get the VS you load the output (2 x 150 watt lamps)then jump M on to standby (make high). your reading of 390v is showing PFC to be fine/AC det is fine 4-5V

          Comment


            #6
            Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

            Originally posted by flocko View Post
            Hi TW how are you jumping the supply,you need to first jump auto ground to ground with mains power to the board you should see 3.5v at P813, then jump RL on to standby (make high), both relays should come in and give you the 5v and 17v rails,to get the VS you load the output (2 x 150 watt lamps)then jump M on to standby (make high). your reading of 390v is showing PFC to be fine/AC det is fine 4-5V
            Good afternon/evening Sir Flocko. I assume you'd have your knighthood by now.

            all of the above is true except no load but I'm not concerned by that as my other PSU is quite happy to run without and produce Va and VS. AC dte and err det are identical on both bad board and good board.

            Really frustrating

            Comment


              #7
              Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

              are you making M_ on high to bring in VS/VA?

              Comment


                #8
                Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                Originally posted by flocko View Post
                are you making M_ on high to bring in VS/VA?
                Both boards are setup the same, yes. One works , one does not

                Comment


                  #9
                  Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                  So two boards, one works and one not, at what point does the second one fail auto ground (3.5v-5v) RL _on or M_on . as at first you say relays click in then drop out and does this three times, is this with the board in the set all hooked up or out and jumped.I have had a few over the years with cracked traces and very hard to spot

                  Comment


                    #10
                    Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                    Originally posted by flocko View Post
                    So two boards, one works and one not, at what point does the second one fail auto ground (3.5v-5v) RL _on or M_on . as at first you say relays click in then drop out and does this three times, is this with the board in the set all hooked up or out and jumped.I have had a few over the years with cracked traces and very hard to spot
                    Out it with simply reset and repeat. To me it's completing the actions to turn it all on but Va and Vs never get a raise. Micro processor does not see the voltage so it cycles and tries again, and again and ..........

                    Installed it will only cycle 3 times.

                    I jus got another POS LG HD same style of PSU. Sometimes works, sometimes not. With this one I can see the 3 cycles, twice the panel will briefly energise, the final time I hear the relays it must be relaxing because the panel never fires, so it's the same program but with voltage generated.

                    Comment


                      #11
                      Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                      the microcontroller will trip the relays if it fails to see the VS ramping up . I expect you have tried power on with no jumps to the board all should come up for a few seconds. I remember that with the older power board if the VS adj pot was turn down to low it would trip the power board with a bang though the speakers and make you jump, worth checking the resistance on the pot of the working board to the faulty one.and check the Uc resistor divider back to the M-controller

                      Comment


                        #12
                        Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                        Originally posted by flocko View Post
                        the microcontroller will trip the relays if it fails to see the VS ramping up . I expect you have tried power on with no jumps to the board all should come up for a few seconds. I remember that with the older power board if the VS adj pot was turn down to low it would trip the power board with a bang though the speakers and make you jump, worth checking the resistance on the pot of the working board to the faulty one.and check the Uc resistor divider back to the M-controller
                        Resistor network is new, pot being bad, well I think it's a long shot since another board was fine until I touched it. I don't understand the no jumps. No jumps installed,(main fitted) you get same behaviour of 3 cycles or actually may only be 2 and last is a reset.

                        Mate, you don't even see a rise in voltage, even if that pot was bad and the VS wa s too low you 'd see something for a wink I feel.

                        she's flatlined, I've got the defib on her but she aint coming back

                        Comment


                          #13
                          Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                          No dont hook up the main board just the mains supply cable, stand alone no jumps and just check the VS

                          Comment


                            #14
                            Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                            Originally posted by flocko View Post
                            No dont hook up the main board just the mains supply cable, stand alone no jumps and just check the VS
                            ok

                            Comment


                              #15
                              Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                              0v

                              Comment


                                #16
                                Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                                others come up 5v +17v

                                Comment


                                  #17
                                  Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                                  Originally posted by flocko View Post
                                  others come up 5v +17v
                                  you're killing me, hangon

                                  Comment


                                    #18
                                    Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                                    For the brief moment the relays latch 17V comes up. The relays don't reset straight away.

                                    Comment


                                      #19
                                      Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                                      And M5V and 5v also present at the same time. pretty much identical results as per jumped

                                      Comment


                                        #20
                                        Re: LG EAY60968801 Power Supply Unit(Plasma 50pk series)

                                        Keep up, so to recap PFC good at 390v but no VS have you changed the L6599A control chip ,what are you seeing on the outputs of Q801/802 primary side of VS transformer ?

                                        Comment

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