Neovo f-419 Power but 1 second of picture

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  • merrik
    New Member
    • Apr 2012
    • 4
    • UK

    #1

    Neovo f-419 Power but 1 second of picture

    Hi Folks.

    Hope you will be able to help me with my neovo f-419.

    It has just started displaying a blank screen despite showing a green power LED. If i turn it on and off again then the picture flashes on for about a second before disappearing.

    Having resurrected an HP and Samsung recently with visibily bad caps i have popped the back off and there are no obvious signs of bloating or leaking.

    Before i launch into anything drastic any advice would be greatly appreciated.

    Please let me know if you need any pictures or meter readings and i will endeavour to provide them.

    Many thanks in advance

    Merrik
  • retiredcaps
    Badcaps Legend
    • Apr 2010
    • 9271

    #2
    Re: Neovo f-419 Power but 1 second of picture

    Originally posted by merrik
    If i turn it on and off again then the picture flashes on for about a second before disappearing.
    2 seconds to black can be

    a) bad caps
    b) bad ccfls
    c) bad ccfl wiring
    d) bad secondary windings on the inverter transformers

    All explained and more starting with post #19 at

    https://www.badcaps.net/forum/showthread.php?t=10419
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    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Neovo f-419 Power but 1 second of picture

      I believe retiredcaps is going to revise the test procedure to rev4 to include this tip,
      you may want to try it to see if you have inverter problem or lamp problem.
      https://www.badcaps.net/forum/showthread.php?t=19987
      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

      • retiredcaps
        Badcaps Legend
        • Apr 2010
        • 9271

        #4
        Re: Neovo f-419 Power but 1 second of picture

        Originally posted by budm
        I believe retiredcaps is going to revise the test procedure to rev4 to include this tip,
        you may want to try it to see if you have inverter problem or lamp problem.
        https://www.badcaps.net/forum/showthread.php?t=19987
        Yes, I will. It is on the "to do" list.
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        Comment

        • merrik
          New Member
          • Apr 2012
          • 4
          • UK

          #5
          Re: Neovo f-419 Power but 1 second of picture

          Hi Folks,

          Sorry for not getting back here sooner but family matters put paid to that for a while but that is all sorted now so hopefully i can to trying to fix this monitor.

          I have attached some pictures that should hopefully meet the requirements for size etc.

          I have replaced all the electrolytics on the main (cream) board apart from C805 as craplins do not stock any this size so i will need to pick one up from RS when i pass next. IIRC this one rarely fails anyway.

          I am still getting 2 secs to black although i think it may now be going to standby (orange) a few secs after that too now.

          I have not yet replaced any caps on the secondary (green) board but these are next on my list.

          I am using a fluke 12 multimeter that does allow me to measure capacitance so is it worth pulling the caps and checking them before replacement?

          Have also had a look at the sticky and worked my way through most of it... trnasistors, mosfets etc but any guidance on specific parts to check based on my boards would be greatly appreciated.

          Many thanks

          G
          Attached Files

          Comment

          • selldoor
            Slow Learner
            • Dec 2010
            • 7870

            #6
            Re: Neovo f-419 Power but 1 second of picture

            Hi - Not the best soldering job I have seen. Can you do a close up of the area with the 4 mosfets near the top of the picture. I will try and compare it to another picture.
            Secondly Caps from maplins are probably not good enough
            for this application - they do not have low enough ESR.
            May just work but you might have it all to redo in a week or two.

            As a first test if you have not already done it, can you check the secondary windings on the Inverter transformers.

            They are at T 901 and T902. Power off (for 5 mins)
            Meter on Ohms 2000 or autoranging test across the two end pins on each transformer
            See here http://lcdparts.net/TransformerDetai...ProductID=2724
            Post results as follow

            T901
            S1-S2 xxxx Ohms
            S3-S4 xxxx ohms etc etc
            Please upload pictures using attachment function when ask for help on the repair
            http://www.badcaps.net/forum/showthread.php?t=39740

            Comment

            • selldoor
              Slow Learner
              • Dec 2010
              • 7870

              #7
              Re: Neovo f-419 Power but 1 second of picture

              Here is a schematic of the power supply
              Attached Files
              Please upload pictures using attachment function when ask for help on the repair
              http://www.badcaps.net/forum/showthread.php?t=39740

              Comment

              • retiredcaps
                Badcaps Legend
                • Apr 2010
                • 9271

                #8
                Re: Neovo f-419 Power but 1 second of picture

                Originally posted by merrik
                I have attached some pictures that should hopefully meet the requirements for size etc.
                Well your pics are easily one of the best in terms of focus and clarity so far this year.
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                Comment

                • merrik
                  New Member
                  • Apr 2012
                  • 4
                  • UK

                  #9
                  Re: Neovo f-419 Power but 1 second of picture

                  Hi,

                  I will take a picture of the U950, U920, U960, U930 area when i have some daylight.

                  Probably right about the caps from craplins although they have conviniently fixed my other monitor (samsung 2232bw) and my wifes (samsung 226bw) in the past.

                  If you have a suggested RS range i will replace with them if a fix looks feasible.

                  Readings on:
                  T901
                  S1-S2 = 1.044 Kohm
                  S3-S4 = 0.927 Kohm

                  T902
                  S1-S2 = 0.913 Kohm
                  S2-S4 = 0.917 Kohm

                  @retiredcaps - thank you for the kind comments

                  Comment

                  • retiredcaps
                    Badcaps Legend
                    • Apr 2010
                    • 9271

                    #10
                    Re: Neovo f-419 Power but 1 second of picture

                    Originally posted by merrik
                    Readings on:
                    T901
                    S1-S2 = 1.044 Kohm
                    S3-S4 = 0.927 Kohm

                    T902
                    S1-S2 = 0.913 Kohm
                    S2-S4 = 0.917 Kohm
                    The readings above suggest T901 S1-S2 is likely bad. One of the windings may have broken.

                    The rule of thumb is that the readings should be within 3% of each other.

                    927 x 1.03 = 954.81
                    1044 x 0.97 = 1012.68

                    I can't quite make out the part number on the transformer even though the pics are excellent quality. What is the part number? Ebay is might have a replacement?
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                    Comment

                    • merrik
                      New Member
                      • Apr 2012
                      • 4
                      • UK

                      #11
                      Re: Neovo f-419 Power but 1 second of picture

                      numbers are covered by some sort of varnish but read as:

                      DG100016500
                      LSEI147A 05196 S

                      Comment

                      • retiredcaps
                        Badcaps Legend
                        • Apr 2010
                        • 9271

                        #12
                        Re: Neovo f-419 Power but 1 second of picture

                        Originally posted by merrik
                        DG100016500
                        No luck on ebay.com for the above. Unless someone else can find an exact replacement, this monitor might be a spare parts monitor.
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                        Comment

                        • Rtech
                          Badcaps Legend
                          • Jul 2010
                          • 1095

                          #13
                          Re: Neovo f-419 Power but 1 second of picture

                          Using the part number EEA-17 as shown on the schematic kindly provided, these are available via Ebay from Hong Kong

                          Comment

                          • selldoor
                            Slow Learner
                            • Dec 2010
                            • 7870

                            #14
                            Re: Neovo f-419 Power but 1 second of picture

                            Thats not great news - they are relatively expensive as Inverter Transformers go. I have been looking to see if there are any similar with the same sort of resistance but it doesnt look that there are. Its not like its a common sort screen either that you could pick up a non working one cheap an salvage a part.

                            Perhaps take it out carefully and re test.

                            Slightly off topic
                            @ retired caps - or anyone who is reading -if it came to the point of abandoning a repair if no transformer was available what might be the effect of adding a 100 ohm resistor to the 3 lower circuits. Brighter lights? Big Bang? Transformer burn-up? - just wondering.
                            Please upload pictures using attachment function when ask for help on the repair
                            http://www.badcaps.net/forum/showthread.php?t=39740

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #15
                              Re: Neovo f-419 Power but 1 second of picture

                              Did you try this board with another set of lamps in another LCD panel?
                              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

                              • retiredcaps
                                Badcaps Legend
                                • Apr 2010
                                • 9271

                                #16
                                Re: Neovo f-419 Power but 1 second of picture

                                Originally posted by selldoor
                                Slightly off topic
                                @ retired caps - or anyone who is reading -if it came to the point of abandoning a repair if no transformer was available what might be the effect of adding a 100 ohm resistor to the 3 lower circuits. Brighter lights? Big Bang? Transformer burn-up? - just wondering.
                                Only one person, maybe two, have tried this and reported it working. See below.

                                https://www.badcaps.net/forum/showth...=resistor+fool

                                Using a cap to fool the inverter pwm ...

                                https://www.badcaps.net/forum/showthread.php?t=13713
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                                Comment

                                • selldoor
                                  Slow Learner
                                  • Dec 2010
                                  • 7870

                                  #17
                                  Re: Neovo f-419 Power but 1 second of picture

                                  Originally posted by retiredcaps
                                  Only one person, maybe two, have tried this and reported it working.
                                  Thanks - I think I have read one of those before - in those cases they are substituting for a broken bulb. I was thinking of balancing the resistances
                                  on a faulty transformer.
                                  Last edited by selldoor; 05-25-2012, 11:16 AM.
                                  Please upload pictures using attachment function when ask for help on the repair
                                  http://www.badcaps.net/forum/showthread.php?t=39740

                                  Comment

                                  • retiredcaps
                                    Badcaps Legend
                                    • Apr 2010
                                    • 9271

                                    #18
                                    Re: Neovo f-419 Power but 1 second of picture

                                    Originally posted by selldoor
                                    Thanks - I think I have read one of those before - in those cases they are substituting for a broken bulb. I was thinking of balancing the resistances
                                    on a faulty transformer.
                                    Sorry, I misunderstood. That is what happens with only 4 hours of sleep.

                                    Now I understand what you are getting at. I wouldn't even know how to "insert" the resistor into the windings though.
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                                    • retiredcaps
                                      Badcaps Legend
                                      • Apr 2010
                                      • 9271

                                      #19
                                      Re: Neovo f-419 Power but 1 second of picture

                                      Originally posted by selldoor
                                      I was thinking of balancing the resistances
                                      on a faulty transformer.
                                      I was thinking about this a bit more and I don't think you can do it. The resistance test is a very simple one, but at least it shows that something is wrong with the secondary winding. If there is something wrong, then it should be replaced as it cannot be expected to operate correctly. The winding is supposed to produce very high voltage and made out of very fine wire.

                                      The best analogy that I can think of right now is a car having one tire that is 15 psi because of a slow leak and three others that are 30 psi. I wouldn't recommend lowering the other three good tires to 15 psi to balance out the ride.

                                      We don't talk too much about a ring tester, but these are standalone devices that are a bit more "sophisticated" and find more faults than the resistance tests.

                                      http://www.anatekcorp.com/test%20equipment.htm
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                                      Comment

                                      • kc8adu
                                        Super Moderator
                                        • Nov 2003
                                        • 8832
                                        • U.S.A!

                                        #20
                                        Re: Neovo f-419 Power but 1 second of picture

                                        i have seen them further apart than that and still work.
                                        look to lamps.
                                        now one that is significantly lower than the rest or open is cause for alarm.
                                        i have never seen a transformer bad that was slightly higher than the others.quite a bit lower or open.

                                        Comment

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