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Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

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    Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

    Bought this in the hope of fixing would like some pointers.

    When i plug in mains chord I get 2 clicks from the relay. (sounds about right to me) When i try an get the tv out of standby, a relay clicks the i get 3 flashes from red led on PSU.

    |v'e done a visual inspection and can't find anything suspicious.

    There are some pen markings on some of the Ybuffer ICS??
    Attached Files
    Last edited by niblettr; 03-26-2016, 04:36 AM.

    #2
    Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

    Hello these are great Tv's deffo worth repairing. Does the standby light on the front of the Tv give any flashes ? If so are they red or blue and how many does it give ?
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      #3
      Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

      red and orange when in stanbye,
      red and blue with fault then contiuous 2 red flashes

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        #4
        Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

        2 red is a Ydrive failure which causes the Vs rail to be dragged down on the Psu therefore locking out the Psu. If you unplug the Y and Xdrive what happens does the Tv flash another fault code ?
        Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

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          #5
          Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

          No change, same flash codes.

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            #6
            Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

            Ok now time to start checking the voltage rails from what they are stated as on the connectors.
            Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

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              #7
              Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

              Originally posted by ReeceyBurger123 View Post
              Ok now time to start checking the voltage rails from what they are stated as on the connectors.
              Ok, got no VSUS even when isolated. PSU fault?

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                #8
                Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                Seems likely
                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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                  #9
                  Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                  ok, found 2x K3314 FETS that are shorted on the middle heatsink on the PSU.
                  I've whipped them out and double checked and there are shorted. Ordered some new one.
                  Bit worried that something further upstream may be bust.
                  I checked some sot23 transitors that looks like may be driving these fets and they checked out ok but 2 diodes measured a bit odd. I got 0.6v drop in both directions....

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                    #10
                    Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                    You should replace the driver chip (connected to the FETs) and the fuse as well.
                    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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                      #11
                      Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                      Probably just the fets quite common on Plasma supplies due to the way they are loaded at start up. Also replace the fuse and should be fine
                      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

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                        #12
                        Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                        Originally posted by ReeceyBurger123 View Post
                        Probably just the fets quite common on Plasma supplies due to the way they are loaded at start up. Also replace the fuse and should be fine
                        You should know now that it is a bad idea to just replace the FETs! Also the startup loading isn't a big deal (just charging the caps, but there is a current limit for a reason.)
                        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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                          #13
                          Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                          Alot of the time in my case the driver has almost never ever been damaged at all Tom. Normally if the Vcc and other input pins have no shorts or low resistance across them or to ground it will be ok. I personally have only had to replace 1in 10 drivers for the repairs like this.

                          It might come back and bit me on the ass but I will sort it.
                          Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                          https://www.facebook.com/Telford-Tel...7894576335359/

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                            #14
                            Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                            thanks for all the input so far.
                            What fuse?

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                              #15
                              Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                              note I also removed the transformer so that I could get to the screws holding the fets to the heatsink.
                              Attached Files

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                                #16
                                Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                                Originally posted by ReeceyBurger123 View Post
                                Alot of the time in my case the driver has almost never ever been damaged at all Tom. Normally if the Vcc and other input pins have no shorts or low resistance across them or to ground it will be ok. I personally have only had to replace 1in 10 drivers for the repairs like this.

                                It might come back and bit me on the ass but I will sort it.
                                For me it's much higher - around 1 in 3 have shown suspect readings - although it does depend on the topology of the supply. Flyback and half bridge is more likely to damage the driver. Flyback due to high peak drain voltages, half bridge due to floating source node
                                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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                                  #17
                                  Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                                  Originally posted by tom66 View Post
                                  For me it's much higher - around 1 in 3 have shown suspect readings - although it does depend on the topology of the supply. Flyback and half bridge is more likely to damage the driver. Flyback due to high peak drain voltages, half bridge due to floating source node
                                  Thats true, I have been lucky so far but I always check them any way Tom I know what too look out for. I guess there is the cases of the controller becoming intermittent as I have had before but thats rare for SMPS tbh.
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                                    #18
                                    Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                                    Sorry guys, what fuse? Do you mean the sub ohms ceramic resistors?

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                                      #19
                                      Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                                      Sorry guys, what fuse?

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                                        #20
                                        Re: Pioneer PDP-LX508D Won't turn on, 3 flashes from PSU

                                        Normally for the Vs fets its in between the filter caps or behind the fets. It might be a ceramic style can fuse.
                                        Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

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