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pioneer pdp-503cmx

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    pioneer pdp-503cmx

    Hey guys well I decided since this TVs been floating around on Craigslist for the last year I had some free time yesterday so I decided to pick it up. It was only 25 bucks. I knew what I was in for because I've tried to rebuild these axy1059-d power supplies in the past. I was under the assumption that I was going to find a blown r133 a blown Q 125 and he q127 MOSFET and 5 blinks of the red standby light.


    Got it home. I'm getting 2 blinks. This shows as DC converter failure y sustain in the blink chart.
    However when I opened it up I have found that somebody already replaced r133 which is supposed to be a .1 ohm with a 10 ohm... and q125 has been replaced. The 10 ohm resistor wasn't even making contact. All has been repaired and I'm still getting the two blinks. Oddly the reason of getting those are because I am NOT getting any 13.5 volt 6.3 volt or -9 volt output everything else seems to want to come up. I have also monitored vsus and even though it does come up to the proper voltage is slow to come up.

    This is the dreaded axy1059-d power supply that pioneer had such a problem with.

    Anyone that has repaired these power supplies in the past should know that the reason that they blow is because of really shotty SMD soldering on the components around the three output MOSFET transistors labeled Q 125 Q 127. I made sure that I hate all those was fresh solder before I attempted anything else. This board is known to fail in catastrophic ways.

    It looks like everything on the bottom primary side is trying to work. Optocouplers seem ok as far as I can tell them. And I'm getting PFC voltage at 390 thereabouts. This unit uses many regulated and non regulated DC voltages along with many DC converters. I have an assumption one is out that controls these three voltages. I'm getting really good 12 volt and good 15 volt and they come right up so that tells me also the PFC circuit is working properly. Anyone worked on these power supplies have any info where to look from here? Thanks and I'll be posting pictures tonight
    Last edited by freakaftr8; 10-26-2015, 08:35 AM.
    Did I leave the soldering iron on?

    #2
    Re: pioneer pdp-503cmx

    If you look where the test points are labeled near the outputs there is no voltages there. The gate on q127 q125 and q124 are all showing voltage so surprisingly there all working.
    Attached Files
    Did I leave the soldering iron on?

    Comment


      #3
      Re: pioneer pdp-503cmx

      Looks like I may have answered my own question. T101 run those lines that are dead off q115. Since q115s gate is operating I would say secondary side problem or possibly the transformer itself is dead?
      Attached Files
      Did I leave the soldering iron on?

      Comment


        #4
        Re: pioneer pdp-503cmx

        I'm totally lost w this thing. I'm getting voltages into all legs of T101. But nothing out. I even tried bypassing the opto isolator to no avail. Can a transformer really go bad?
        Did I leave the soldering iron on?

        Comment


          #5
          Re: pioneer pdp-503cmx

          I know nothing about this model or its power supply, but yes a transformer can go bad. For example,

          a) the windings can be shorted
          b) the windings can be open
          c) some transformers have a thermal fuse that can go open

          Since I don't have any fancy equipment like a scope or ring tester, I only check transformers by measuring the resistance of the primary and secondary. This test may not help though.

          I suggest measuring the resistance of T101 and T102. Though the two are not the same, it will give you an idea of what to expect.

          A clear picture of pcb backside T101 and T102 would help. Check the soldering of T101 as well.

          BTW, on this TV, does the main board need to send a signal to bring up 13.5 volt 6.3 volt or -9V rails?
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          Comment


            #6
            Re: pioneer pdp-503cmx

            Originally posted by retiredcaps View Post
            BTW, on this TV, does the main board need to send a signal to bring up 13.5 volt 6.3 volt or -9V rails?
            Found my own answer to question in service manual.

            Attached Files
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            Comment


              #7
              Re: pioneer pdp-503cmx

              Interesting. Anyhow now I have good 6.3 -9 and 13.5 but lost 12 and 15v. I didn't even do anything. Odd
              Did I leave the soldering iron on?

              Comment


                #8
                Re: pioneer pdp-503cmx

                Could also be a failed fuse, or the FET is faulty, or shorted output diode.
                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

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