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Insignia ns-55d420a16. Blinking red light no backlight

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    Insignia ns-55d420a16. Blinking red light no backlight

    Tested power supply output getting 12 volts with no main board. Tested with main board 12 volt output is dipping appears that power supplies restarting. Hooked external load directly to 12 volt and it's doing the same thing. Suggestions?
    Attached Files

    #2
    Re: Insignia ns-55d420a16. Blinking red light no backlight

    Try heating the electrolytic capacitors on the powerboard with a hairdryer, see if the voltages stabilize if only for a bit.
    Last edited by nomoresonys; 02-28-2021, 01:53 PM.

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      #3
      Re: Insignia ns-55d420a16. Blinking red light no backlight

      What load did you put on the 12V supply line. It says maximum 3 Amp. Does the 14V supply line also drop in line with the 12V ?
      Attached Files
      Last edited by dick_barton; 02-28-2021, 01:54 PM.
      Willing to help but I'm no expert.

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        #4
        Re: Insignia ns-55d420a16. Blinking red light no backlight

        Unfortunately no change. 12v drops to 3v then cycles between 0 and 3v. Remove all but main filter caps and tested esr, they are all low, but i believe .02 is within spec for a 25v 1000Uf low esr cap.

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          #5
          Re: Insignia ns-55d420a16. Blinking red light no backlight

          Originally posted by dick_barton View Post
          What load did you put on the 12V supply line. It says maximum 3 Amp. Does the 14V supply line also drop in line with the 12V ?
          Not sure on the load, but it was dialed all the way down.

          The board silkscreen showed 16v not 14, and its didn't match up with the connector so i assumed it was incorrect. I'm not getting any other voltage other than the 12 with or without the mainboard plugged in.

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            #6
            Re: Insignia ns-55d420a16. Blinking red light no backlight

            Look the solder joints over on the powerboard real closely, see if you have any bad/cold joints. As always be VERY CAREFUL when dealing with the DEADLY/HOT side of the board.
            Last edited by nomoresonys; 02-28-2021, 04:56 PM.

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              #7
              Re: Insignia ns-55d420a16. Blinking red light no backlight

              Also check over the diodes and resistors if you haven't already.

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                #8
                Re: Insignia ns-55d420a16. Blinking red light no backlight

                If your power supply matches the schematic then if the 12V is running so should the 14V (16V) because they are both derived from the same transformer T831
                If that supply is missing then you need to double check all the components in that area.
                Attached Files
                Willing to help but I'm no expert.

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                  #9
                  Re: Insignia ns-55d420a16. Blinking red light no backlight

                  maybe also check VD829, VD825 and VD805.

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                    #10
                    Re: Insignia ns-55d420a16. Blinking red light no backlight

                    Thanks for the assistance. Ended up being VD819 (MBR101 50 CTF - E1 434881). Having trouble finding a suitable replacement.
                    Would FCH10A20 suffice?
                    Last edited by knoxrebel; 02-28-2021, 07:08 PM.

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                      #11
                      Re: Insignia ns-55d420a16. Blinking red light no backlight

                      Data sheet FCH10A20: https://www.alldatasheet.com/datashe.../FCH10A20.html

                      Data sheet MBR10150CTF-E1: https://www.alldatasheet.com/datashe...150CTF-E1.html do those match up?

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