Need INVFT320A Inverter

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  • dkneyle
    Badcaps Veteran
    • Dec 2013
    • 441
    • Australia

    #1

    Need INVFT320A Inverter

    This is an inverter used in a range of 32 inch CFL TVs. Mine has an open transformer winding. Thought maybe someone had one in the bottom of their parts drawer? Or maybe even the transformer, which has a part number of IT-133 06CK typed on it.

    There is one on FleaBay for A$50 landed in Oz, so if I can't pick up a bargain somewhere, then I'll probably buy that one. Only just makes it an economical repair.

    Ironically, I stripped down the same model for scrap a couple of years ago and I sold the inverter! When fault finding today's TV I had no PS-On signal from the mainboard. I'd saved the previous mainboard because I was unable to confirm it was functional. Dropped it into this current repair and everything came up except the backlights. Flashlight test showed all other systems functional, voltages to inverter were correct. Troubleshooting inverter led to the conclusion the transformer had failed.
    Attached Files
    Last edited by dkneyle; 03-10-2017, 09:31 PM. Reason: Added image of inverter
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Need INVFT320A Inverter

    So one of the two inverter transformer has open winding on the high Voltage side?
    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

    • dkneyle
      Badcaps Veteran
      • Dec 2013
      • 441
      • Australia

      #3
      Re: Need INVFT320A Inverter

      I'm assuming it's the high voltage winding, although the companion transformer winding reads ~3 ohms which suggests perhaps it's a primary winding? Very hard to trace circuit as the transformer tracks are whited out. I do have a schematic so I'll pull that out and see if I can find how the windings are configured. BTW, the fuse on the board is OK.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Need INVFT320A Inverter

        You have two transformer drive circuits (4 MOSFETs per transformer). So even if you have one bad transformer you should see the backlights from the good transformer come on for seconds before the protection circuit kicks in.
        We need good clear high res straight shot pictures of the board to see how the circuits are laid out on 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

        • dkneyle
          Badcaps Veteran
          • Dec 2013
          • 441
          • Australia

          #5
          Re: Need INVFT320A Inverter

          The manual does not include a circuit diagram for the inverter. The reverse side of board has no tracks. I suspect it is a multi layer board. I've tried to indicate in the pics the discrepancy I was measuring.
          Attached Files

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Need INVFT320A Inverter

            OK, thanks for the pictures.
            The set of four MOSFETs are connected in parallel, the primary winding of the inverter transformers are connected in series, the drive circuit for the primary winding is Half-bridge drive.
            At this point I would remove that suspected transformer and look at the bottom side to side what condition it has and that will also show us how the HV winding is connected to the legs of the transformer.
            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

            • dkneyle
              Badcaps Veteran
              • Dec 2013
              • 441
              • Australia

              #7
              Re: Need INVFT320A Inverter

              It's the strangest thing Bud. I can't get any continuity on the secondary side of those transformers. I mean, I know how a transformer is configured. There's 6 tabs coming out of the transformer; 3 aside I'm assuming. On the primary side I get a very low DC ohms reading across two of those tabs (the upper two in the image shown in post above). No apparent connection on the third tab. But apart from that, nothing on any other tab. Nothing on the secondary side. And it's the same for both transformers. Got me thinking I didn't know how to use a meter! I de-soldered one of those transformers but no secrets were revealed. The power FETs check out OK.
              I will buy a secondhand board as a replacement. I'll post up the readings I get on those transformers just so people who might track down this thread for their own fault finding purposes are able to see the outcome.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Need INVFT320A Inverter

                Can I see good clear pictures of the bottom side of the transformer?
                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

                • dkneyle
                  Badcaps Veteran
                  • Dec 2013
                  • 441
                  • Australia

                  #9
                  Re: Need INVFT320A Inverter

                  I'll get those pics to you tonight (our time) when I go home from work.
                  The CFL tubes must be in series as there is only one wire from each HV outlet socket. So the secondary coils must be in series I would assume to be able to work and complete the circuit?

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: Need INVFT320A Inverter

                    Originally posted by dkneyle
                    I'll get those pics to you tonight (our time) when I go home from work.
                    The CFL tubes must be in series as there is only one wire from each HV outlet socket. So the secondary coils must be in series I would assume to be able to work and complete the circuit?
                    No, they are not in series, if they are, it will take very very high Voltage to fire up the lamps and to sustain the lamp to stay on.
                    What is the LCD panel P/N? It may have circuit board with Ballast cap per each lamp (and then parallel connected) if it uses CCFL, if it use EFL then the lamps will be connected in parallel without Ballast cap for each lamp.
                    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

                    • dkneyle
                      Badcaps Veteran
                      • Dec 2013
                      • 441
                      • Australia

                      #11
                      Re: Need INVFT320A Inverter

                      Counting the transformer tags from top left in a counter-clockwise direction, 1 & 2 are the primary windings with virtually 0 DC ohms. The secondary appears to be 3 and 5 with a ~15 DC ohms. 4 and 6 appear not connected and are probably mounting supports?
                      Both transformers measure the same. Not sure why my initial measurements suggested a bad TX?
                      I have ordered another board (listed as "new" but I doubt it).
                      I'm wondering about my initial diagnosis? I had a TV that wouldn't start. I exchanged with a mainbaord I had lying around and it fired up and the flashlight test showed an image. I thought I measured a Power On voltage at the inverter along with the 24 volts required to power the board, so I made an assumption of a crook inverter. Now I'm wondering?
                      Attached Files

                      Comment

                      • dick_barton
                        Badcaps Legend
                        • Aug 2015
                        • 6642
                        • Wales

                        #12
                        Re: Need INVFT320A Inverter

                        I would expect the primary and secondary windings to terminate on opposite ends of the transformer. In an earlier post you showed 3 ohms between the ends of one of the transformers. If you measure those two points on the board and or the transformer is it still 3 ohms?
                        Last edited by dick_barton; 03-13-2017, 04:56 AM.
                        Willing to help but I'm no expert.

                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #13
                          Re: Need INVFT320A Inverter

                          One thing we do not know is that if you are getting the BL-ON signal or not.
                          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

                          • Andrew F. Ali
                            Badcaps Legend
                            • Jan 2014
                            • 2450
                            • Trinidad & Tobago

                            #14
                            Re: Need INVFT320A Inverter

                            Originally posted by budm
                            One thing we do not know is that if you are getting the BL-ON signal or not.
                            Check whether you have BL-ON or not. Perhaps you may have a bad CCFL. Consider another possibility IF you have a bad CCFL.....Converting to LED backlight.

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #15
                              Re: Need INVFT320A Inverter

                              https://www.badcaps.net/forum/attach...1&d=1489211243

                              The ON/OFF pin is the BL-ON pin so check and see if it has >2.5VDC when TV is ON.
                              Might as well check the IN and EX dim pis also.
                              I was assuming that you had already check those signal since you seem to know about the PS-ON so I would think you will know about other signals as well.
                              Last edited by budm; 03-13-2017, 09:37 AM.
                              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

                              • dkneyle
                                Badcaps Veteran
                                • Dec 2013
                                • 441
                                • Australia

                                #16
                                Re: Need INVFT320A Inverter

                                The transformer has IT-133 06CK printed on it.
                                The reason I was prepared to purchase a complete new board was because I did measure BL-On and it was about 3.5volts. I had good 24 volt supply, no sign of CFL's firing and then going off after 2 seconds. In the past when repairing TVs I've seen these symptoms, realised it was a SMT board that was essentially too difficult for me to fault find and/or repair, so just bit the bullet and ordered another board.
                                I really should go to the effort of replacing that TX and checking if I actually have high voltage or not at the output. It could be CFL failure I suppose?
                                Now I'm on my learning curve. Explain what the IN and EX DIM lines do, where they are driven from, etc?

                                Comment

                                • Andrew F. Ali
                                  Badcaps Legend
                                  • Jan 2014
                                  • 2450
                                  • Trinidad & Tobago

                                  #17
                                  Re: Need INVFT320A Inverter

                                  Should IN be EN and EX DIM be P-DIM? Look again at the jack and see if you have another pin with the label PWM, P-DIM or ADJ. You have 24Vdc and BL-ON. So all you need to get is 4 LED strips and the Universal LED Driver Bd and you are well on your way to convert to LED, as an alternative.

                                  Comment

                                  • Andrew F. Ali
                                    Badcaps Legend
                                    • Jan 2014
                                    • 2450
                                    • Trinidad & Tobago

                                    #18
                                    Re: Need INVFT320A Inverter

                                    No post

                                    Comment

                                    • vinceroger69
                                      Badcaps Legend
                                      • Mar 2012
                                      • 6714
                                      • uk

                                      #19
                                      Re: Need INVFT320A Inverter

                                      Originally posted by Andrew F. Ali
                                      Should IN be EN and EX DIM be P-DIM? Look again at the jack and see if you have another pin with the label PWM, P-DIM or ADJ. You have 24Vdc and BL-ON. So all you need to get is 4 LED strips and the Universal LED Driver Bd and you are well on your way to convert to LED, as an alternative.
                                      what does the picture on the tv look like after this conversion as the leds will not have diffuser lens fitted over them like on proper strips

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #20
                                        Re: Need INVFT320A Inverter

                                        https://www.badcaps.net/forum/attach...1&d=1489211243
                                        As labeled on the board:
                                        IN-PW?(M) = Internal PWM dimming
                                        EX-PW?(M) = External PWM Dimming
                                        ON/OFF = BL-ON BACKLIGHTS ON/OFF
                                        These signal are from the main board.
                                        the Dimming control signal will one of the two but not both.
                                        Attached Files
                                        Last edited by budm; 03-14-2017, 08:58 AM.
                                        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

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