Replacing Capacitors on Viewsonic N2751w

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  • lkvee
    Senior Member
    • Feb 2009
    • 198

    #1

    Replacing Capacitors on Viewsonic N2751w

    Got it with power issues - previous user said it wouldn't turn on. I trust his observations. I also can't test ESR ... yet.

    Might not need to do so after looking at the power board. Here's what I found:

    CapXon 220uf 25V (all 3 popped)
    CapXon 1000uf 25V (both not popped - 20mm high, 10mm diameter)
    CapXon 1500uf 16V (both popped - 20mm high, 10mm diameter)

    I'm wondering if the Taicon capacitors need replacing (1000uf 35V). They're 20mm high and about 13 mm in diameter. I see "C0607(M)" imprinted on the side.

    The smaller capacitors are:

    33uf 35V (3)
    2.2uf 50V
    10uf 50V

    I'm thinking of replacing just the CapXon capacitors with reputable replacements that are the same in physical dimensions, capacitance, and voltage.

    I also see Elite capacitors on the video board. That makes me wonder.

    What else should I examine?
    Attached Files
  • retiredcaps
    Badcaps Legend
    • Apr 2010
    • 9271

    #2
    Re: Replacing Capacitors on Viewsonic N2751w

    Originally posted by lkvee
    Might not need to do so after looking at the power board. Here's what I found:

    CapXon 220uf 25V (all 3 popped)
    CapXon 1000uf 25V (both not popped - 20mm high, 10mm diameter)
    CapXon 1500uf 16V (both popped - 20mm high, 10mm diameter)
    Replace ALL the electrolytic capacitors on the power board except the largest one which rarely, but not never, fails. Capxon caps bulged or not don't have the greatest track record or reputation. Use Panasonic FR, FM, or FC (in that order of preference).

    The caps on the logic board don't undergo the same stress or heat so you can leave them alone.
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    Comment

    • PCBONEZ
      Grumpy Old Fart
      • Aug 2005
      • 10661
      • USA

      #3
      Re: Replacing Capacitors on Viewsonic N2751w

      There are A LOT of Capxon caps that have specs FAR better than FC.
      .
      Look up the series at Capxon and find the actual specs.
      - Not that hard for Capxon caps.
      http://www.google.com/#sclient=psy-a...w=1280&bih=839

      Then you can choose replacements spec'ed at least as well as the originals.
      .
      Mann-Made Global Warming.
      - We should be more concerned about the Intellectual Climate.

      -
      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

      - Dr Seuss
      -
      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
      -

      Comment

      • lkvee
        Senior Member
        • Feb 2009
        • 198

        #4
        Re: Replacing Capacitors on Viewsonic N2751w

        How about those caps ranging from 2.2uf to 33uf? Recap or leave 'em alone?

        Comment

        • retiredcaps
          Badcaps Legend
          • Apr 2010
          • 9271

          #5
          Re: Replacing Capacitors on Viewsonic N2751w

          Originally posted by lkvee
          How about those caps ranging from 2.2uf to 33uf? Recap or leave 'em alone?
          ALL means ALL on the power board. The little caps play an important part of the whole system. In particular, there is a SMPS startup cap (little - between 22uf - 47uF @ 50V) that is key to the entire power supply properly starting.

          The little caps shouldn't cost more than 20 or 25 cents each.
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          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

          • PCBONEZ
            Grumpy Old Fart
            • Aug 2005
            • 10661
            • USA

            #6
            Re: Replacing Capacitors on Viewsonic N2751w

            Agree.
            Those aren't bad as often as the bigger caps but the small cost to replace them is worth it to save the hassle [and shipping cost] of having to order caps twice when Murphy's Law comes into play.
            .
            Mann-Made Global Warming.
            - We should be more concerned about the Intellectual Climate.

            -
            Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

            - Dr Seuss
            -
            You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
            -

            Comment

            • retiredcaps
              Badcaps Legend
              • Apr 2010
              • 9271

              #7
              Re: Replacing Capacitors on Viewsonic N2751w

              Originally posted by retiredcaps
              The little caps shouldn't cost more than 20 or 25 cents each.
              Looks like digikey raised prices at bit. 33, 31, and 33 cents respectively.

              http://search.digikey.com/scripts/Dk...35v+fm&stock=1

              http://search.digikey.com/us/en/prod...0313-ND/266322

              http://search.digikey.com/us/en/prod...0316-ND/266325

              Digikey's quantity = 1 is 2x the cost when quantity = 50. Digikey used to have price breaks at quantity = 10.
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              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.

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              Comment

              • lkvee
                Senior Member
                • Feb 2009
                • 198

                #8
                Re: Replacing Capacitors on Viewsonic N2751w

                I replaced all but the Taicons (1000uf 35V) and the three 33uF (35V) caps.

                I still have no reaction from powerup, so I'm going to spring for the 33uF (and 1000uF) replacements. All the other replacements were from Rubycon, NCC, and the 1500uF caps were from Sanyo.

                I tested the 4A 250V fuse and got continuity.

                What's the likelihood I'll be looking for the root cause somewhere else other than the capacitors?

                Comment

                • selldoor
                  Slow Learner
                  • Dec 2010
                  • 7870

                  #9
                  Re: Replacing Capacitors on Viewsonic N2751w

                  Hi - you will need to post some more photos if we have to look elesewhere.

                  Please post good clear pictures of each board, straight on, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

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

                  Examples of what is needed
                  https://www.badcaps.net/forum/attach...1&d=1290283049

                  https://www.badcaps.net/forum/attach...7&d=1280167246

                  You can test for power at the BIG Cap. Multimeter on 600vDC
                  You have to observe polarity so positive probe on positive leg of Big cap
                  and negative probe on negative leg of big cap. - Dealing with high voltages
                  so care required and heatsinks should not be touched. Post result.
                  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

                    #10
                    Re: Replacing Capacitors on Viewsonic N2751w

                    "I still have no reaction from powerup"
                    Do you mean you still do not have the 5VStandby power supply? You have to have this working first otherwise nothing else will come on.
                    http://s807.photobucket.com/albums/y..._MARCH%202005/
                    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

                    • lkvee
                      Senior Member
                      • Feb 2009
                      • 198

                      #11
                      Re: Replacing Capacitors on Viewsonic N2751w

                      I pressed the power button but I failed to see any reaction from the TV. I do know the fuse is still good, but I may want to take time to post pictures as recommended, just in case I created shorts in my soldering.

                      I also need serious hand-holding to figure out to test the 5V power supply. The closest test I've performed was to test the 5V and 12V voltages on a bare external hard drive kit power supply, since the tested hard drive started to smoke. Those voltages tested within normal parameters. I don't even know where the put the leads on the TV to test the 5V power supply.

                      I have yet to and plan to replace the three 33uF 35V capacitors, as they have been considered to be critical in starting up the TV. I'll need to buy these, and hope I have two 1000uF 35V caps - I have yet to replace the two Taicons.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Replacing Capacitors on Viewsonic N2751w

                        Please see attached pictures for the 5VDC standby test point on the board.
                        You may have real bad problem with bad transistor and Zener diode also.
                        http://photobucket.com/images/pwr%20...20fsp212-3f01/
                        Attached Files
                        Last edited by budm; 05-14-2012, 03:12 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

                        • selldoor
                          Slow Learner
                          • Dec 2010
                          • 7870

                          #13
                          Re: Replacing Capacitors on Viewsonic N2751w

                          Can you do this- to establish we are getting primary voltage.

                          You can test for power at the BIG Cap. Multimeter on 600vDC
                          You have to observe polarity so positive probe on positive leg of Big cap
                          and negative probe on negative leg of big cap. - Dealing with high voltages
                          so care required and heatsinks should not be touched. Post result.
                          Please upload pictures using attachment function when ask for help on the repair
                          http://www.badcaps.net/forum/showthread.php?t=39740

                          Comment

                          • lkvee
                            Senior Member
                            • Feb 2009
                            • 198

                            #14
                            Re: Replacing Capacitors on Viewsonic N2751w

                            I haven't gotten around to testing the biiiiiig capacitor (because I want more guidance around me when I do it). I have replaced the three 33uF capacitors with Chemicon KMC series. There's no change in behavior - there's no reaction upon hitting that power button. The only capacitors from the original power board are the Taicons.

                            I am a little worried about my soldering for the three caps. I believe I started to lift the tracings on two of them. I hope the pictures are clear enough.
                            Attached Files

                            Comment

                            • selldoor
                              Slow Learner
                              • Dec 2010
                              • 7870

                              #15
                              Re: Replacing Capacitors on Viewsonic N2751w

                              ok - you can always check the traces are good by testing resistance between
                              the joint and the next joint along the trace. ( Power off)
                              While you are doing that and until you get up enough confidence to do some voltage checks try this.
                              With power off meter set on ohms 2000 test across the CN1 connector
                              (next to the fuse) Black on N pin Red on L and post the result.
                              Please upload pictures using attachment function when ask for help on the repair
                              http://www.badcaps.net/forum/showthread.php?t=39740

                              Comment

                              • NBE
                                New Member
                                • Feb 2013
                                • 1
                                • USA

                                #16
                                Re: Replacing Capacitors on Viewsonic N2751w

                                I am having a similar issue. I can turn mine on, I have sound, but no picture. I can see that the back light is on, so that isn't the issue. I removed the power supply and checked the caps. None of them are bulging, so I am not sure where to go from here. Thanks in advance for any help.
                                God Bless, Glenn

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #17
                                  Re: Replacing Capacitors on Viewsonic N2751w

                                  If you have backlights but nothing on the screen (just the glowing screen), it means that the T-CON is bad (blown fuse), or it is not getting the power from the main board.
                                  Please read my guide about LCD TV at the bottom of my signature to understand more. You will need to check the T-CON board voltage and fuse.
                                  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

                                  • lkvee
                                    Senior Member
                                    • Feb 2009
                                    • 198

                                    #18
                                    Re: Replacing Capacitors on Viewsonic N2751w

                                    The TV's still in the same spot with the same problem. I think I've replaced all but the largest capacitor (I'll check again later).

                                    I'll check again later because I noticed some repair kits include a part with the designation of Q7. I don't think it's a capacitor, but rather a zener diode.

                                    If anyone has the specs of Q7 and its location on the board (if it's not actually "Q7"), please post a reply!

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #19
                                      Re: Replacing Capacitors on Viewsonic N2751w

                                      Same as this? 2n2222, or 2n4401. http://s807.photobucket.com/user/bud...?sort=3&page=1
                                      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

                                      • lkvee
                                        Senior Member
                                        • Feb 2009
                                        • 198

                                        #20
                                        Re: Replacing Capacitors on Viewsonic N2751w

                                        Without looking at MY board, I'm going to say yes, it's the same.

                                        I see the 2n2222 but I don't see the 2n4401 (or at least something with that designation). Which one should I order to replace the Q7 part?

                                        Thanks for replying!

                                        Comment

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