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Blinking stby led on a TD systems TV with 17IPS11 PS

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    Blinking stby led on a TD systems TV with 17IPS11 PS

    Hi There!
    I have a TV set (model TD Systems K32DLV1H) which doesn't power up.
    During power off, the stby red led is on, as it should, then I press power button on remote and the led starts blinking, endlessly.

    Sounds to me like a PS problem. TV is kinda alive as it stays in Stand-by, recognizes power up button from remote, etc, but can't really power up.

    Internal PS is a 17IPS11. First inspection shows no damaged components, no swollen caps, and multimeter shows all diodes are good. Also there's a dual diode transistor shaped component on a heatsink that measures ok, and also a (probably) mosfet on another heatsink measuring no shorts on any pin

    Being lead by other forums it makes me believe it could have to deal wih the backlight. Now the question is, how can I determine, without removing the LCD panel, if the issue is with the LED strips themselves, or the LED voltage generator in the PS? Or maybe you guys can provide any other hint on what to check?

    Any help would be greatly appreciated!!
    Thanks

    #2
    Re: Blinking stby led on a TD systems TV with 17IPS11 PS

    Need pictures of boards and connectors. Voltages from power board to main and led in standby and when powered up. You may be able to unplug t-con and power up might bring up backlights. You can tap screen to see if backlights are working. Also use flashlight to see if there is an image on screen.
    Last edited by dskall; 04-03-2022, 12:53 PM.
    I assume no responsibility for any stupid suggestions I might post.

    Comment


      #3
      Re: Blinking stby led on a TD systems TV with 17IPS11 PS

      Hi.

      Turn-on the tv and Check led voltage. If voltage around 70V-90V replace led bars.
      https://www.badcaps.net

      Comment


        #4
        Re: Blinking stby led on a TD systems TV with 17IPS11 PS

        Originally posted by dskall View Post
        Need pictures of boards and connectors. Voltages from power board to main and led in standby and when powered up. You may be able to unplug t-con and power up might bring up backlights. You can tap screen to see if backlights are working. Also use flashlight to see if there is an image on screen.
        Ok I will check this tomorrow as right now I have the PSU board out for further tests
        Thanks!

        Comment


          #5
          Re: Blinking stby led on a TD systems TV with 17IPS11 PS

          Originally posted by arizanotlari View Post
          Hi.

          Turn-on the tv and Check led voltage. If voltage around 70V-90V replace led bars.
          I did test this before I took the PSU board out, it measured 19v. Short in the LEDS?

          Comment


            #6
            Re: Blinking stby led on a TD systems TV with 17IPS11 PS

            No. unplug led cable from psu. connect probs to led socket. turn-on tv and measure the voltage at the first moment.
            https://www.badcaps.net

            Comment


              #7
              Re: Blinking stby led on a TD systems TV with 17IPS11 PS

              Ok I got some measurements
              All this is assuming that the verson on my PS is this one:

              (mine is using the 2x6 connector enclosed in a box)
              Before power up measurements:
              (1) "PIN1": 0v
              (3) "STDBY": 2,5v
              (5) "BLON_OFF": 0v
              (7) "PWM_DIM": 0v
              (9) "STBY_ON": pulsing around 250mV
              (11) "+12v": +12v
              (13) "+12v": +12v

              Then when I power it on:
              (1) "PIN1": 0v
              (3) "STDBY": 0v
              (5) "BLON_OFF": 0v
              (7) "PWM_DIM": 3,3v
              (9) "STBY_ON": pulsing around 130mV
              (11) "+12v": +12v
              (13) "+12v": +12v

              Now about LED power. It doesn't matter if I have the wire plugged to the leds or not. 0v when stdby, that rises to 20v when triting to power on. No higher pulses than 20v.

              Someone asked to try with T-con removed, this set doesn't have a T-con board. But I tried while the ribbon from MAIN to LCD was unplugged with no changes.

              Thanks everyone!

              Comment


                #8
                Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                Looks like maybe a mainboard problem.
                Ok looking at pin 9 should have 5v I think. So maybe power supply. I am not good with schematics. Maybe someone else ccan jump in with schematic knowledge.
                Last edited by dskall; 04-04-2022, 12:15 PM.
                I assume no responsibility for any stupid suggestions I might post.

                Comment


                  #9
                  Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                  Mainboard? Why do you think that? I still believe it's the PS

                  Comment


                    #10
                    Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                    Originally posted by edugimeno View Post
                    Ok I got some measurements
                    All this is assuming that the verson on my PS is this one:Thanks everyone!
                    yours measurements could be error.. can you disconnect the MB from the PCB totaly. just plug in wall and give yours new measurements on the socket which it goes to MB !!

                    Comment


                      #11
                      Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                      Pin 3 and 5 not good. I misunderstood your problem at first. If the standby led is blinking continuously, there is a problem with the motherboard.
                      https://www.badcaps.net

                      Comment


                        #12
                        Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                        The stdby led blinks only when I try to power it on, but it stays lit when powered off (as it should). Once I try to power it on, it blinks, and then there's no way to power it off again (getting it to solid lig again) unless I unplug it from mains and plug it back in

                        My measurements varied just a little when I tried with MB unplugged. I still believe it's the PS, as I don't even get +5v on STBY_5V when unplugged from MAIN board

                        Comment


                          #13
                          Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                          Originally posted by edugimeno View Post
                          (9) "STBY_ON": pulsing around 250mV
                          Sorry PIN 9 is labeled "+5V STBY" on the schematic. I don't get this voltage

                          Comment


                            #14
                            Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                            Pin 9 is not connected, forget it.

                            What is mainboard name?
                            https://www.badcaps.net

                            Comment


                              #15
                              Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                              I give you a tip: if you connect 12V 1A adapter to pin 1 (ground) and pin 13 (plus) motherboard working without psu. You can test mb this way.
                              https://www.badcaps.net

                              Comment


                                #16
                                Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                                maybe check the electrolytic caps closest to the connector and check all the diodes, does seem like your standby voltage is looking funky.

                                Comment


                                  #17
                                  Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                                  pictures would help.

                                  Comment


                                    #18
                                    Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                                    Originally posted by edugimeno View Post
                                    My measurements varied just a little when I tried with MB unplugged. I still believe it's the PS, as I don't even get +5v on STBY_5V when unplugged from MAIN board
                                    MANNN... how it come your measurements varied just a little when the MB unplugged ???? how it come you have 12V on the socket and the MB didn't send any power on signal.... can you explain...???? there are no power boards work from alone to provide operation VCC 12V with out power on... LOL

                                    Comment


                                      #19
                                      Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                                      Originally posted by Diah View Post
                                      MANNN... how it come your measurements varied just a little when the MB unplugged ???? how it come you have 12V on the socket and the MB didn't send any power on signal.... can you explain...???? there are no power boards work from alone to provide operation VCC 12V with out power on... LOL
                                      Some Vestel boards do that. 12V always on. Other 3 signal send from mb to psu.
                                      https://www.badcaps.net

                                      Comment


                                        #20
                                        Re: Blinking stby led on a TD systems TV with 17IPS11 PS

                                        Originally posted by arizanotlari View Post
                                        Some Vestel boards do that. 12V always on. Other 3 signal send from mb to psu.
                                        so you mean at this PCB the 12V always active... then the MB should have stepdown circuit to let the SPI run 3.3V to send signal back to PCB via the OPTO to run PFC hight >400V to provide the T to work and provide AC -- to DC 24V for LEDS BL. only this i can imagine it. so funny design... would better to them to let it work with external transformer...
                                        Last edited by Diah; 04-04-2022, 03:48 PM.

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