RCA LED52B45RQ wont stay on

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  • jasonbay13
    Senior Member
    • Jul 2014
    • 185
    • usa
    #1

    RCA LED52B45RQ wont stay on

    i have the same tv and power supply board as in the forum thread below, though i have different symptoms than anywhere else i've looked and cannot find a schematic or anything else to help me.

    the problem is that the red light comes on and i get 5v at +5vsb but when i press the power button the red light goes out for half a second and the +5vsb drops to 2v or so (almost too quick for my meter to read a drop at all) and the +12v shows 11v or so for a split second and +5v shows 4-5v for a split second.
    This is repeatable as many times as you want to press the power button, except!!! i did get it to turn on twice.

    would this be a power supply problem or a mainboard issue? sounds to me like something is shorting out but if so, then how did it come on? checked esr of +5v cap and checked good as new no other caps are visibly problematic either.

    seems to me there is a hot spot on the board around the ic/diode by C48 (discoloration of the board and what appeared to be cracked solder joints i attempted to reflow with no change in behavior).





    https://www.badcaps.net/forum/showthread.php?t=71141
    Tags: None
    • R_J
      Badcaps Legend
      • Jun 2012
      • 9535
      • Canada
      #2
      Re: RCA LED52B45RQ wont stay on

      Post pictures of YOUR board. It might be obvious whats wrong when someone sees your board. Did you check D18A and D18B ?
      Last edited by R_J; 04-10-2019, 10:47 AM.

        Comment

        • jasonbay13
          Senior Member
          • Jul 2014
          • 185
          • usa
          #3
          Re: RCA LED52B45RQ wont stay on

          i got it working. i touched up a few more solder joints and changed out c14 (33ohms) and c5 (2 ohms).

          can anyone tell me why c14 is important to have a low esr?

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: RCA LED52B45RQ wont stay on

              C14 is the startup/running cap for the standby power supply section, when it is bad it will cause the power supply to start/stop so that is why you see the 5VSTBY goes up and down with heavy load.
              What is the value of the cap? It is usually around 47 ~ 56uF 50V, you can get away using good quality 105c general purpose cap.
              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

                • jasonbay13
                  Senior Member
                  • Jul 2014
                  • 185
                  • usa
                  #5
                  Re: RCA LED52B45RQ wont stay on

                  ok, so.... the tv will come on sometimes. and now seems to have a similar problem as the thread i linked in the first post.

                  plug it in and the red light comes on. press the power button and the tv turns on. anywhere from 0 seconds to 20 minutes the tv will shut off. 5vstb stays at 5v and on/off stays at 4.65v (after tv has shut off).

                  i've tried forcing on\off and backlight without luck. power supply shuts down.

                  however, if i leave either the backlight on/off cable disconnected or the led connectors disconnected it stays on, just no backlight.


                  in conclusion: i either have a bad power supply board or bad backlight (which i've read is a problem with this tv).

                    Comment

                    • jasonbay13
                      Senior Member
                      • Jul 2014
                      • 185
                      • usa
                      #6
                      Re: RCA LED52B45RQ wont stay on

                      woo wee!

                      it exploded in my face!
                      i was plugging it in to try and read some voltages and q10 exploded.
                      unfortunately for me there are no replacements for this board and i have no idea what that ic was, or if the power supply board was even at fault though it and the main board both had bad caps.

                      i guess this one goes in the dumpster unless anyone wants parts.
                      Last edited by jasonbay13; 11-11-2019, 09:54 AM.

                        Comment

                        • nomoresonys
                          Badcaps Legend
                          • Jan 2013
                          • 12156
                          • U.S.
                          #7
                          Re: RCA LED52B45RQ wont stay on

                          Being an rca, it probably should be trashed, ran across this ad, don't know anything about them tho: https://www.wsrepairs.com/product-pa...rca-led52b45rq

                            Comment

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