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Visio VO370m - 1 second backlight

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    Visio VO370m - 1 second backlight

    Just got a Visio VO370m that powers on (visio symbol goes from amber to white) and the backlights come on for 1-2 seconds. Set responds to the PWR button, turning off. All fuses check OK. Visually inspected capacitors, nothing apparent. Resoldered all the pins of the inverters and transformers. Getting ready to measure voltages on all regulators.
    Attached Files
    Last edited by ahickman; 12-04-2012, 01:26 PM.

    #2
    Re: Visio VO370m - 1 second backlight

    Is there an image on the screen although backlights are off?

    Comment


      #3
      Re: Visio VO370m - 1 second backlight

      Power supply cap (C4) = 394 VDC
      U11 (7805 reg.) = 5.03 VDC
      T-con had 11.97 VDC on both sides of the fuse

      U8
      0 VDC (adj)
      1.25 VDC (out)
      3.26 VDC (in)

      U2
      2.04
      3.28
      4.95

      U5
      1.37
      2.61
      4.95

      U4
      2.05
      3.30
      4.99

      U9
      1.25
      2.50
      4.95

      Comment


        #4
        Re: Visio VO370m - 1 second backlight

        Yes, there are images when i shine a light. Inverter board?

        Comment


          #5
          Re: Visio VO370m - 1 second backlight

          Shine a bright light on the screen after the back lights cut off. If you can see video then the problem is either the inverter side of the power board is shutting down, or a bad lamp in the panel is causing the inverter to shut down.

          Comment


            #6
            Re: Visio VO370m - 1 second backlight

            How are those small blue ballast caps on the output side of the inverter transformers/ Do they look like it has some brownish color to the body. Transformer resistance checking will be next.
            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


              #7
              Re: Visio VO370m - 1 second backlight

              Your photo is quite clear enough and I don't have selldoor's eyesight, but this may be your transformer that budm alluded to

              http://www.lcdparts.net/TransformerD...ProductID=2796

              Measure and report the resistance between S1-S2 and S3-S4 for all of them
              --- begin sig file ---

              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

              Please do not post inline and offsite as they slow down the loading of pages.

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              Comment


                #8
                Re: Visio VO370m - 1 second backlight

                The xformer you found does not match the pinouts for the transformer on the board. Below are more detailed pictures of the front/back. I searched for the replacement part, but was unable to find a pinout. Going to desolder one of them now.
                Attached Files

                Comment


                  #9
                  Re: Visio VO370m - 1 second backlight

                  Its always difficult when you cant find the exact part number and just have to go by something near - i couldnt find it either.
                  You need to do the long test ( which actually takes longer to type than to do.)
                  Draw a rough pic and number the pins 1 to 9 or whatever - Power OFF Meter on 2000 ohms test pin1>pin2 Pin1 > pin3 Pin 1>Pin4 and so on then Pin2>pin3 pin2 >pin3 Pin2>pin4 to pin 2 >pin9 then pin3 >pin4 pin 3 >pin5 etc etc At some point you will get something in the range 600 to 1200 ohms make a note of those pins and check the same pins on the other transformer. and report results
                  ( Only the high numbers)

                  Looks like the secondaries are on the side nearest the edge of the board but you cant always tell.
                  Last edited by selldoor; 12-05-2012, 09:39 AM.
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment


                    #10
                    Re: Visio VO370m - 1 second backlight

                    When you remove the transformer an look at the bottom side then it will be easier to figure out.
                    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


                      #11
                      Re: Visio VO370m - 1 second backlight

                      Hope this diagram make sense. Looks like a single primary with 13 ohm resistance and two separate secondary turnings with ~1.8K ohms resistance.
                      Attached Files

                      Comment


                        #12
                        Re: Visio VO370m - 1 second backlight

                        Budm, what is the best way to test the blue caps. I have an ESR meter, but don't know if the mylar type respond.

                        Comment


                          #13
                          Re: Visio VO370m - 1 second backlight

                          That would do it! now check the other transformers - results should be within 3%
                          Please upload pictures using attachment function when ask for help on the repair
                          http://www.badcaps.net/forum/showthread.php?t=39740

                          Comment


                            #14
                            Re: Visio VO370m - 1 second backlight

                            ESR won't work for picofarad caps, unless you have an LCR meter.
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                            Comment


                              #15
                              Re: Visio VO370m - 1 second backlight

                              Those ballast caps when they go bad it will have leakage resistance from 10K to 200K, good cap will show open circuit. Just set your meter to highest resistance scale and tak the reading, just do not touch the two probes with you fingers otherwise you will be reading your body resistance.
                              Your VO370M does not look anything like the one I worked on a few weeks ago.
                              http://s807.photobucket.com/albums/y...izio%20VO370M/
                              Last edited by budm; 12-05-2012, 10:47 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


                                #16
                                Re: Visio VO370m - 1 second backlight

                                All primary windings are 12 ohms. All but one transformer have secondary windings close to 1760 ohms. One transformer has secondaries that read 1696 and 1820 ohms.

                                Comment


                                  #17
                                  Re: Visio VO370m - 1 second backlight

                                  The 1820 ohms is suspicious, but it is only 3.5% out. Although the rule is 3%, it is so close to be hard to tell.
                                  Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                  For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                  Comment


                                    #18
                                    Re: Visio VO370m - 1 second backlight

                                    ok the one off the board just passes the last one with 1696 is a fail. now to find a new one -as i say i could read the number but could not find one. You may have to try and find a whole board - even a faulty one should have at least one transformer that is good.
                                    Please upload pictures using attachment function when ask for help on the repair
                                    http://www.badcaps.net/forum/showthread.php?t=39740

                                    Comment


                                      #19
                                      Re: Visio VO370m - 1 second backlight

                                      Thanks Selldoor. Looking for a replacement now.

                                      Comment


                                        #20
                                        Re: Visio VO370m - 1 second backlight

                                        http://www.ebay.com/itm/130757248772
                                        --- begin sig file ---

                                        If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                                        We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                                        Please do not post inline and offsite as they slow down the loading of pages.

                                        --- end sig file ---

                                        Comment

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