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UE40EH5000KXXU No power completely dead

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    #21
    Re: UE40EH5000KXXU No power completely dead

    Could be overlooking IC707 - LD1117AG measuring 3.29v between pins 1 & 2.
    Using chassis as gnd,
    Pin 1 0v
    pin 2 3.29v
    pin 3 5.22v

    Comment


      #22
      Re: UE40EH5000KXXU No power completely dead

      That is fine, it is 3.30V LDO.
      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

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        #23
        Re: UE40EH5000KXXU No power completely dead

        IC201 - IC204 are likely ok too, Seems like most of the low voltages are there. I would think 3.3 volts should find its way to the keypad, time to start following the traces back from the keypad.
        Last edited by R_J; 09-08-2019, 06:50 PM.

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          #24
          Re: UE40EH5000KXXU No power completely dead

          Thanks, appreciate the help.

          Will have to continue with it tomorrow (later today)! Getting late and eyes tired, having trouble focusing.

          Comment


            #25
            Re: UE40EH5000KXXU No power completely dead

            The keypad 3.3v line traces back to pins 3, 4 & 8 of an SMD 8 pin ic marked WAA P which is IC302.

            Pin 1 - 0v
            Pin 2 - 3.29v
            Pin 3 - 0v
            Pin 4 - 0v
            Pin 5 - 1.6v
            Pin 6 - 5.22v
            Pin 7 - 5.27v
            Pin 8 - 0.02v

            Pin 1 does not appear to be connected to anything.
            Attached Files
            Last edited by notallbad; 09-10-2019, 03:47 PM.

            Comment


              #26
              Re: UE40EH5000KXXU No power completely dead

              Pins 3 & 4 appear to be gnd.
              Pin 8 is also connected to gnd but a couple of ohms higher.

              Comment


                #27
                Re: UE40EH5000KXXU No power completely dead

                Which plug is for the keyboard? the ic seems a long way from the plugs, Also if you look at the edge of the board next to the tuner input, there are holes with names FUNC_xxx etc. I would think the third hole would be FUNC_VCC or the sixth hole FUNC_BT_VCC could have 3.3v?
                Last edited by R_J; 09-10-2019, 05:14 PM.

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                  #28
                  Re: UE40EH5000KXXU No power completely dead

                  CN1202 is keypad
                  CN201 is psu

                  Func_P_Det is 3.29v
                  Func_bt_vcc is 0v
                  Func_vcc is 0.02v

                  Comment


                    #29
                    Re: UE40EH5000KXXU No power completely dead

                    I'm sure you checked for the 3.3 volts without the keypad plugged in, just in case it is killing the voltage. I don't see any reason for switching that voltage on and off.

                    Comment


                      #30
                      Re: UE40EH5000KXXU No power completely dead

                      Same with keypad connected or disconnected.

                      IC1203 - S24CS0 - No vcc on pin 8

                      IC601 & IC604 - S24CS0, have 5v on pin 8.

                      Comment


                        #31
                        Re: UE40EH5000KXXU No power completely dead

                        Try and trace ic1203's vcc, maybe it goes to a transistor where they switch the vcc on and off, I do see a resistor between WP and VCC so maybe they do switch the vcc on and off.
                        Last edited by R_J; 09-10-2019, 06:57 PM.

                        Comment


                          #32
                          Re: UE40EH5000KXXU No power completely dead

                          Ic1203's vcc pin 8 goes to ic202 - 1G1 R tran.

                          pin 8 shows short cct to keypad vcc pin 3.
                          Attached Files
                          Last edited by notallbad; 09-10-2019, 07:22 PM.

                          Comment


                            #33
                            Re: UE40EH5000KXXU No power completely dead

                            What voltage do you have on IC202, It "might" be a mcp1700 3.3v ldo, It IS marked as an IC
                            Last edited by R_J; 09-10-2019, 08:29 PM.

                            Comment


                              #34
                              Re: UE40EH5000KXXU No power completely dead

                              If IC202 is an mcp1700 the pins are as follows
                              pin 1 gnd 0v
                              pin 2 output 0.02v
                              pin 3 input 5.27v

                              It is marked 1G1 R.

                              Comment


                                #35
                                Re: UE40EH5000KXXU No power completely dead

                                And that could explain the missing 3.3v , Either there is a short on the output or the ic is bad and not supplying the voltage.
                                When I said it was marked as an ic I ment its board designation. so its not a transistor (Q) or diode(D)
                                Last edited by R_J; 09-11-2019, 09:03 AM.

                                Comment


                                  #36
                                  Re: UE40EH5000KXXU No power completely dead

                                  Shall see if I can lift the output leg from the board and check for 3.3v.

                                  Comment


                                    #37
                                    Re: UE40EH5000KXXU No power completely dead

                                    You might risk breaking the ic trying to lift one leg, If it shows voltage the ic could still be bad.

                                    Comment


                                      #38
                                      Re: UE40EH5000KXXU No power completely dead

                                      Wait, it is not possible that all that ICs are fed by a small sot23, diif has said one important thing, he knows of a common problem on Welltrend chip, and since it is a standby MPU it is explained why no led blinkings, second, i remember that AVboard has only one AOZ1051P, the remaining two pwm chips are from Texas, something like TPS4427, right? The most important thing to do is to use a bench PSU and feed on the 3,3v rail (put for example on the pin8 of IC2301, the settings eeprom) starting with 3,3v and 0A and rising the Amps until something gets hot, especially the MPU..

                                      Comment


                                        #39
                                        Re: UE40EH5000KXXU No power completely dead

                                        That ic202 (sot23-3) is NOT the main source for the 3.3 volts for the board. IC707 is likely the main source for 3.3 volts as it has 3.3 volts on its output.
                                        Last edited by R_J; 09-11-2019, 03:28 PM.

                                        Comment


                                          #40
                                          Re: UE40EH5000KXXU No power completely dead

                                          Another hint, the AOZ1051P in its datasheet it's marked as "Not recommended for new designs", so i guess it has reliability problems..

                                          Comment

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