Dynex DX-LCD32-09 wont turn on. Lights for half second.

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  • lookimback
    Badcaps Legend
    • Aug 2013
    • 1489
    • USA
    #1

    Dynex DX-LCD32-09 wont turn on. Lights for half second.

    This is a different Dynex than the one I fixed yesterday. I thought I was going to have an easy one because I could have swapped boards to figure out which one to focus on. No such luck. Inverter board is different in this one. Its only 1 sided, transformers are different, that fuse that was bad on the other one, doesn't seem to be present in this one.

    Visual observation: inconclusive

    Beginning pin testing now.

    Starting with the power board.

    Top connector

    PON. 2.4v
    Gnd. OK
    5v 5.15v
    Gnd. OK
    Gnd. OK
    16v. 15.5v
    16v. 15.5v
    Gnd. OK
    5v. 5.09v
    Gnd. OK
    9v. 9.09v
    Gnd. OK
    32v. 32.37v

    Middle connector

    PON. 5.166v
    PWM. 3.39v
    Gnd. OK
    Gnd. OK
    Gnd. OK
    24v. 23.75v
    24v. 23.75v

    Bottom connector

    PON. 5.166v
    PWM. 3.39v
    Gnd. OK
    Gnd. OK
    Gnd. OK
    Gnd. OK
    Gnd. OK
    24v. 23.75v
    24v. 23.75v
    24v. 23.75v
    24v. 23.75v
    24v. 23.75v

    Can't check voltages across PFC without flipping the power board and I don't think its necessary. Voltages all seem correct. Getting P/ON signal from main. 24v is present so power board is coming on. I was pretty sure it was an inverter problem when I first plugged it in. Certain of it now. I'm just trying to develop a protocal I will follow on every set I work on.

    Beginning testing on inverter board now.

    PWM. 3.38v
    PON. 5.16v
    Pin 4. 3.23v
    Gnd. OK
    Gnd. OK
    Gnd. OK
    Gnd. OK
    Gnd. OK
    24v. 23.75
    24v. 23.75
    24v. 23.75
    24v. 23.75
    24v. 23.75

    Voltages all seem correct. P/ON signal present.


    Beginning testing resistances on transformers now. Since the pins are not numbered I'll call the top left (connector side) pin 1 and go clockwise to 8. From what I can tell from the resistances, testing should be across pins 1 and 8, and, 4 and 5.

    T7
    1-8. 966 ohms
    4-5. 975 ohms

    T6
    1-8. 974 ohms
    4-5. 968 ohms

    T5
    1-8. 977 ohms
    4-5. 973 ohms

    T4
    1-8. 971 ohms
    4-5. 973 ohms

    T3
    1-8. 969 ohms
    4-5. 1090 ohms

    T2
    1-8. 968 ohms
    4-5. 974 ohms

    T1
    1-8. 951 ohms
    4-5. 956 ohms

    At this point I'm thinking maybe T3 is bad. Maybe T1 as well. I'm going to post this now to get feedback. Meanwhile, I'll look for a service manual or at least a data sheet for the PWM IC.
    Attached Files
    Last edited by lookimback; 10-12-2013, 09:32 PM.
    ------------signature starts here------------


    Tags: None
    • ben7
      Capaholic
      • Jan 2011
      • 4059
      • USA
      #2
      Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

      T3's readings do seem a tad high.
      Muh-soggy-knee

        Comment

        • lookimback
          Badcaps Legend
          • Aug 2013
          • 1489
          • USA
          #3
          Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

          Over 100 ohms higher than the rest. Yes, I think that may be it.
          ------------signature starts here------------


            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

              I agree that T3 dose look bad.
              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

                • lookimback
                  Badcaps Legend
                  • Aug 2013
                  • 1489
                  • USA
                  #5
                  Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                  I'm going to look for a replacement. I looked into just replacing the board but its $60-$70. I'll look and see what a new transformer will cost.
                  ------------signature starts here------------


                    Comment

                    • lookimback
                      Badcaps Legend
                      • Aug 2013
                      • 1489
                      • USA
                      #6
                      Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                      Wish I could pull one from a different board just to see if it is the problem. I have some with the same number of pins. Footprint probably different. If the resistances are the same, could I just solder wires to it and the board just to test it?
                      Last edited by lookimback; 10-13-2013, 01:35 PM.
                      ------------signature starts here------------


                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA
                          #7
                          Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                          Sometime it is cheaper to buy a board so you will have spare transformers, more likely the other will fail too, if you can find the board real cheap or if the transformer can be had for less than $5 then you can see which way will be cheaper. If you going to sell the TV then buying the transformer will be cheaper than buying the board.
                          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

                            • lookimback
                              Badcaps Legend
                              • Aug 2013
                              • 1489
                              • USA
                              #8
                              Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                              Originally posted by budm
                              …more likely the other will fail too
                              Other what? I have to open it back up and get the numbers from the transformer. I forgot to do that while I had it open last night.
                              ------------signature starts here------------


                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA
                                  #9
                                  Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                                  Other transformers. I did that before, replace one transformer, the a few month later another one failed, I should have bought replacement board to have spare parts from the old board.
                                  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

                                    • lookimback
                                      Badcaps Legend
                                      • Aug 2013
                                      • 1489
                                      • USA
                                      #10
                                      Re: Dynex DX-LCD32-09 wont turn on. Lights for half second.

                                      These are both the exact same inverter boards. One is from an Element and is about $40. The other is from a Dynex and is about $70.

                                      http://m.ebay.com/itm/251279072662?nav=SEARCH&sbk=1

                                      http://m.ebay.com/itm/190882564273?nav=SEARCH&sbk=1

                                      Transformer number is 2874015400. Its about $9 plus shipping.
                                      Last edited by lookimback; 10-14-2013, 02:21 AM.
                                      ------------signature starts here------------


                                        Comment

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