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    Dead FTA receiver power supply

    Hi there,
    I tried to troubleshoot a FTA receiver with dead power supply, with good fuse but no outputs voltage. First I did measure the voltage on big capacitor (68uF/400V) and is 103V only...is it normal ??... also had a tiny brown residue on vent... please see attached photos.
    Attached Files

    #2
    Re: Dead FTA receiver power supply

    There should be about 165~170VDC on that Primary DC filter cap (line voltage x 1.414 = V on the cap). Are the four rectifier diodes close by OK, no leaking liquid from the cap. Put your meter in AC mode and read the AC ripple voltage on that cap for me, be real careful.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

    Comment


      #3
      Re: Dead FTA receiver power supply

      suiramix - what are you going to use it for? My FTA has been sitting around collecting dust ever since Beverly got Nagra 2.
      "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

      -Leonid Brezhnev (On the Yom Kippur War)

      Comment


        #4
        Re: Dead FTA receiver power supply

        Hi budm,

        Thanks for your help...the AC ripple voltage on primary DC filter cap is 49.5V...my guess is this voltage is way to high than normal !!!
        Yes mokingbird, I missed too Beverly, this receiver is for international programs from Europe ...

        Comment


          #5
          Re: Dead FTA receiver power supply

          Budm
          I replaced the primary DC filter cap (original CapXon had a leakage on positive terminal, see attached photo) but there is no output voltages on secondary circuit ...there is an IC PWM controller NCP 1200AP60 and MOSFET IRF830...please advise ...
          Attached Files

          Comment


            #6
            Re: Dead FTA receiver power supply

            Originally posted by suiramix View Post
            Budm
            I replaced the primary DC filter cap (original CapXon had a leakage on positive terminal, see attached photo) but there is no output voltages on secondary circuit ...there is an IC PWM controller NCP 1200AP60 and MOSFET IRF830...please advise ...
            Check the rectifier diodes.
            Muh-soggy-knee

            Comment


              #7
              Re: Dead FTA receiver power supply

              So what voltage are you getting on the cap now? 165~170VDC? When that cap was not filtering properly, it will allow large AC to be fed to the circuits and can cause damages to the components.
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

              Comment


                #8
                Re: Dead FTA receiver power supply

                budm,
                Yes, the voltage on the new primary DC filter cap is 166.5V DC...the NCP1200P60 has Vcc (pin 6) voltage reading of 6.3V(?) ...the C22 external bulk capacitor is close to MOSFET heatsink and could be dried up (no visible leakage) !

                Comment


                  #9
                  Re: Dead FTA receiver power supply

                  Your bridge is OK, there is a small startup cap by the MOSFET on the heat sink, I would try replacing that cap first, with that much AC ripple before, the IC could be damaged, but try that start up first. That VCC is too low, most SMPS min running voltage spec is about 10V or more.
                  Never stop learning
                  Basic LCD TV and Monitor troubleshooting guides.
                  http://www.badcaps.net/forum/showthr...956#post305956

                  Voltage Regulator (LDO) testing:
                  http://www.badcaps.net/forum/showthr...999#post300999

                  Inverter testing using old CFL:
                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                  http://s807.photobucket.com/user/budm/library/

                  TV Factory reset codes listing:
                  http://www.badcaps.net/forum/showthread.php?t=24809

                  Comment


                    #10
                    Re: Dead FTA receiver power supply

                    Hi budm,
                    Again, you're right, I replaced that small start-up capacitor (22uF/16V), the voltage went to 10.8V and the power supply is alive again !!!..Thanks again for you input !!!

                    Comment


                      #11
                      Re: Dead FTA receiver power supply

                      Great! Thanks for the feedback.
                      Never stop learning
                      Basic LCD TV and Monitor troubleshooting guides.
                      http://www.badcaps.net/forum/showthr...956#post305956

                      Voltage Regulator (LDO) testing:
                      http://www.badcaps.net/forum/showthr...999#post300999

                      Inverter testing using old CFL:
                      http://www.badcaps.net/forum/showthr...er+testing+cfl

                      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                      http://s807.photobucket.com/user/budm/library/

                      TV Factory reset codes listing:
                      http://www.badcaps.net/forum/showthread.php?t=24809

                      Comment

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