Aoc n20wb

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  • ronhayes
    TV Engineer
    • Mar 2014
    • 458
    • UK

    #1

    Aoc n20wb

    Hi All
    Wonder if any one can help ? I have just had a 20" monitor off my brother he said it was working fine but one day when he switched it on the screen flashed on then went dark.
    When i switched it on the green light stays on but no picture displayed, when i used a torch i could see the picture , so no backlights.
    I took it apart and tested the backlights with my lcd tester i used the inverter included in that kit.
    As you can see from the photo's i have included the screen working with my lcd tester connected.
    When i check the volts on each backlight plug at switch on the volts jump up then go back down to 0v after about one second.
    Can not find any info on this monitor or a supplier for power board ?
    Any help much appreciated.
    Attached Files
  • vinceroger69
    Badcaps Legend
    • Mar 2012
    • 6714
    • uk

    #2
    Re: Aoc n20wb

    on the psu is there any writing on top of the inverter transformer as maybe faulty winding on it

    Comment

    • ronhayes
      TV Engineer
      • Mar 2014
      • 458
      • UK

      #3
      Re: Aoc n20wb

      Hi Vince
      Thank you for your help this is what is printed on it.
      2374302205p , DARFON2029R , 822012.
      Sorry i have not been very active on badcaps but i am a very poorly man at the moment .

      Comment

      • ronhayes
        TV Engineer
        • Mar 2014
        • 458
        • UK

        #4
        Re: Aoc n20wb

        I have just looked for the inverter transformer on the net and can only see one listed in America for $7.

        Comment

        • ronhayes
          TV Engineer
          • Mar 2014
          • 458
          • UK

          #5
          Re: Aoc n20wb

          Sorry i mean China

          Comment

          • vinceroger69
            Badcaps Legend
            • Mar 2012
            • 6714
            • uk

            #6
            Re: Aoc n20wb

            can you take a picture of the top of the transformer and also on the bottom side of the transformer too see if we can work out what windings/pins we need to check the ohms on

            EDIT ron heres a good picture of the windings can you check the ohms on them
            http://www.iccfl.com/product_info.ph...oducts_id=5450
            I have looked online but cant seem too find the winding specs hopefully budm? may have a idea of what the reading should be on a good transformer as you have tested the ccfls and ruled them out already.
            Last edited by vinceroger69; 04-06-2018, 05:59 AM.

            Comment

            • ronhayes
              TV Engineer
              • Mar 2014
              • 458
              • UK

              #7
              Re: Aoc n20wb

              Here they are hope they are clear enough ?
              Attached Files

              Comment

              • vinceroger69
                Badcaps Legend
                • Mar 2012
                • 6714
                • uk

                #8
                Re: Aoc n20wb

                Originally posted by ronhayes
                Here they are hope they are clear enough ?
                thanks ron did you see my edit in the above post?

                Comment

                • ronhayes
                  TV Engineer
                  • Mar 2014
                  • 458
                  • UK

                  #9
                  Re: Aoc n20wb

                  Hi Vince
                  I have just looked at your edit.
                  Does it have to be removed to test ?
                  And what pins should i test ?

                  Comment

                  • vinceroger69
                    Badcaps Legend
                    • Mar 2012
                    • 6714
                    • uk

                    #10
                    Re: Aoc n20wb

                    test in circuit is ok, if you look at the picture in the link i sent you the winding wires you can see which pins they go to and need to test

                    as monitors are so cheap nowadays you may not want too spend much on parts i wonder if you could use something like this the problem maybe without a schematic finding where to wire it up to and finding where to mount it if you have room
                    https://www.ebay.co.uk/itm/Universal...wAAOSwu4BVu1OW
                    Last edited by vinceroger69; 04-06-2018, 06:29 AM.

                    Comment

                    • ronhayes
                      TV Engineer
                      • Mar 2014
                      • 458
                      • UK

                      #11
                      Re: Aoc n20wb

                      I have measured ohms in the 20k setting on diode the two centre pins on the end with the six pins i get short 0.00 ohms with buzzer and the two single pins i get 0.46ohms with buzzing.

                      Comment

                      • ronhayes
                        TV Engineer
                        • Mar 2014
                        • 458
                        • UK

                        #12
                        Re: Aoc n20wb

                        Yes that would be a good alternative but would need to be guided on how to connect ?
                        I am sure i could find some ware to mount it.
                        Last edited by ronhayes; 04-06-2018, 06:48 AM.

                        Comment

                        • vinceroger69
                          Badcaps Legend
                          • Mar 2012
                          • 6714
                          • uk

                          #13
                          Re: Aoc n20wb

                          Originally posted by ronhayes
                          I have measured ohms in the 20k setting on diode the two center pins on the end with the six pins i get short 0.00 ohms with buzzer and the two single pins i get 0.46ohms with buzzing.
                          i cant find any info on the specs for this transformer im hoping a more experienced member will let us know if this is ok or not
                          regarding wiring the universal board im not sure but maybe if you can find the lcd panel number? we can look at the lvds pin out and see if we can work where to connect it up too

                          Comment

                          • vinceroger69
                            Badcaps Legend
                            • Mar 2012
                            • 6714
                            • uk

                            #14
                            Re: Aoc n20wb

                            i wonder how close this service manual is too your monitor yes this service manual uses two inverter transformers but it maybe close enough too help fix yours its a dixon n20w but made by aoc
                            Attached Files

                            Comment

                            • ronhayes
                              TV Engineer
                              • Mar 2014
                              • 458
                              • UK

                              #15
                              Re: Aoc n20wb

                              Here is a picture of the labels on the lcd panel
                              Attached Files

                              Comment

                              • vinceroger69
                                Badcaps Legend
                                • Mar 2012
                                • 6714
                                • uk

                                #16
                                Re: Aoc n20wb

                                hopefully budm will see this thread and have a idea if those transformer readings are ok or not or any help on fitting that universal board

                                Comment

                                • ronhayes
                                  TV Engineer
                                  • Mar 2014
                                  • 458
                                  • UK

                                  #17
                                  Re: Aoc n20wb

                                  Yes hopefully he will.

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #18
                                    Re: Aoc n20wb

                                    There are two 8-P9N SMD DUAL MOSFETs (very close to the transfomer for driving the primary side of the Inverter transformer. What are their P/N?
                                    BTW, you lamp tester is made to test 4 lamps, what happen you you connect just only one lamp at a time, do you see the backlights come on for seconds?
                                    BTW, that board 2202139401p is also used in Viewsonic VA2208W, Haans-G HF2296.
                                    Last edited by budm; 04-06-2018, 08:56 PM.
                                    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

                                    • ronhayes
                                      TV Engineer
                                      • Mar 2014
                                      • 458
                                      • UK

                                      #19
                                      Re: Aoc n20wb

                                      MOSFET P/N are 4502c AA8 GAR.
                                      Yes the tester can test all four ,So i connected all four but i only used it on its lower volts
                                      Backlights came on and stayed on.

                                      Comment

                                      • vinceroger69
                                        Badcaps Legend
                                        • Mar 2012
                                        • 6714
                                        • uk

                                        #20
                                        Re: Aoc n20wb

                                        budm what was your thoughts on post 11 good or bad? as i couldnt find any specs on the transformer

                                        Comment

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