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BenQ V2400W power button quits working after period of shut down until power recycled

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    BenQ V2400W power button quits working after period of shut down until power recycled

    I have a nice BenQ V2400W. I replaced the power board with a new one and it worked perfectly - except: after not using it overnight, the button will not turn on the unit; if I unplug it and wait a minute, then plug it back in, then it works fine, you can shut it off, turn it on, anytime; until it sits off for 8 hours or so. I have to unplug it and then plug it back in for a minute, then it works fine again until it sits off for a while. I have taken it apart about 7 times; it has few caps, and they are a good brand, and look fine. I did replace the twp 220 caps with 50V replacements (just in case) but there are 5 330 35v caps, all look good, nicholson brand. No bulges, etc. I did replace all the 220 caps on the signal board, nothing has worked. Other forum posts suggest one does just not understand the buttons, but this is not the case. Has anyone experienced this with this monitor? I am at my wits end. I have filled out tech requests three times with BenQ, but they never respond. If anyone has any insight into this issue, I would love the help. The monitor is beautiful, but useless to anyone normal for daily use. I can solder parts on and off easily, but have no troubleshooting experience with the board components so I need help. Thanks in advance.

    #2
    Re: BenQ V2400W power button quits working after period of shut down until power recy

    1) Post clear focused pictures following my sig file below exactly in this composition.

    https://www.badcaps.net/forum/showpo...94&postcount=1

    2) Do you own a multimeter and know how to use it?
    --- 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


      #3
      Re: BenQ V2400W power button quits working after period of shut down until power recy

      Was the replacement board EXACTLY the same? same number and revision .
      Please upload pictures using attachment function when ask for help on the repair
      http://www.badcaps.net/forum/showthread.php?t=39740

      Comment


        #4
        Re: BenQ V2400W power button quits working after period of shut down until power recy

        Should have thought of this earlier- Are you able to try the monitor with a different pc.
        Does it do the same? Also can you try with different input vga dvi hdmi does it still do the same. I have read that it could be an interaction with the video card - what card are you using - try reseating the video card. Do you switch the pc off or put it on standby or just leave it on and the screen goes into standby itself?
        Please upload pictures using attachment function when ask for help on the repair
        http://www.badcaps.net/forum/showthread.php?t=39740

        Comment


          #5
          Re: BenQ V2400W power button quits working after period of shut down until power recy

          Thanks for all your posts. Sorry I haven't checked in a while. I do have a multimeter, but don't really know how to use it to test components. The board was an exact replacement, new not used, part# on label=5E0F902001, and the silk-screened board number is: 4H.0F902.A00. I have tried both DVI and VGA cables, but don't have HDMI output to try. It does the same thing with either cable. I am using it as I post this; I will try it with my laptop connected to it to see if overnight it stays off again, but I tried it with a different pc I no longer have with the same results.

          I have not tried the "2 seconds to off" tests, but I am willing to. I can solder components (built Heathkits as a kid!) and have fixed a couple other monitors by replacing caps, but I really don't know how to test components with a multimeter - I have one, but don't even know which components are which all the time. I am a careful person though, and can follow directions.

          I can post pictures next time I take it apart again, but I have really examined the two boards, and there is absolutely nothing that looks burned or any caps that bulge at all, or any obvious bad solder connections. I am willing to try any suggestions. This is a really nice display but drives me crazy that something with what seems to be a simple problem is not known about; however, I have read many posts from others (not in this forum) complaining about the same thing, erratic on/off performance. Any help will be greatly appreciated.

          Comment


            #6
            Re: BenQ V2400W power button quits working after period of shut down until power recy

            Sorry, forgot. I always switch it off, but I have tried leaving it go to standby, orange light lit, and it doesn't go off if I just leave it on standby. If someone needs me to post pics, I will take it apart again and post some close-ups.

            Comment


              #7
              Re: BenQ V2400W power button quits working after period of shut down until power recy

              Originally posted by tombodude View Post
              I have tried leaving it go to standby, orange light lit, and it doesn't go off if I just leave it on standby.
              So when its in that state and you press the power button does it come on?

              Just to check the problem again - (sorry)
              Monitor off and unplugged. Computer on and connected to monitor
              Plug In - what happens - standby? or on? - what is power light doing.
              If standby - press the power button - comes on - what is power light doing.
              Works ok without problem other buttons all work ok?
              Switch monitor off with power button - what is power light doing.
              Power down computer.
              10 minutes later
              Power up computer
              Press power on Monitor - comes on no problem?

              Press power off on monitor - power light does what?
              Switch off pc
              6 hours later (what is the longest you can leave it for it not to come on)
              Switch on pc
              Press power button on monitor- Does nothing? what does power light do.
              Unplug Monitor then plug back in - Button works properly?

              Is that the correct summary perhaps you can cut and paste it and enter what the light does etc .
              Is it plugged direct to mains or through an UPS or powersaver.
              Please upload pictures using attachment function when ask for help on the repair
              http://www.badcaps.net/forum/showthread.php?t=39740

              Comment


                #8
                Re: BenQ V2400W power button quits working after period of shut down until power recy

                Originally posted by tombodude View Post

                I can post pictures next time I take it apart again, but I have really examined the two boards, and there is absolutely nothing that looks burned or any caps that bulge at all, or any obvious bad solder connections. I am willing to try any suggestions. This is a really nice display but drives me crazy that something with what seems to be a simple problem is not known about; however, I have read many posts from others (not in this forum) complaining about the same thing, erratic on/off performance. Any help will be greatly appreciated.
                I hate to say this, but if electronics repair were as simple as looking for burned components or bulged caps, then everyone would be a repair expert and there would be no need for this forum or any sort of test equiptment. Parts can look look fine and still be bad. Lack of photos is really killing this thread.

                Comment


                  #9
                  Re: BenQ V2400W power button quits working after period of shut down until power recy

                  Originally posted by jetadm123 View Post
                  I hate to say this, but if electronics repair were as simple as looking for burned components or bulged caps, then everyone would be a repair expert and there would be no need for this forum or any sort of test equiptment. Parts can look look fine and still be bad. Lack of photos is really killing this thread.


                  My best guess that the caps on the power board are dried up and have high ESR (ohms or equivalent series resistance). As the monitor warms up or never shuts down, the cap's ESR drops allowing the circuit to work.

                  See my standard answer

                  https://www.badcaps.net/forum/showpo...84&postcount=3
                  Last edited by retiredcaps; 05-30-2012, 05:00 PM.
                  --- 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


                    #10
                    Re: BenQ V2400W power button quits working after period of shut down until power recy

                    Originally posted by retiredcaps View Post


                    My best guess that the caps on the power board are dried up
                    Hmm... OP says

                    The board was an exact replacement, new not used, part# on label=5E0F902001

                    I am not saying a new board coudn't have dried up caps but I had sort of
                    discounted that idea.
                    Please upload pictures using attachment function when ask for help on the repair
                    http://www.badcaps.net/forum/showthread.php?t=39740

                    Comment


                      #11
                      Re: BenQ V2400W power button quits working after period of shut down until power recy

                      Originally posted by selldoor View Post
                      I am not saying a new board coudn't have dried up caps but I had sort of
                      discounted that idea.
                      True and I agree with everything you say. Until we see pictures and get voltage readings, I like to start with making sure the power supply is stable.
                      --- 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


                        #12
                        Re: BenQ V2400W power button quits working after period of shut down until power recy

                        Sorry I have not had time to come back to this monitor until today. I really appreciate your help. I talked to someone at BenQ tech support today, finally, but they have no one who knows how these work, actually, just how to use them, cable them, etc. for end users.

                        I have pics of all but the front of the inverter board, need to uninstall that one yet, but here is everything else.

                        I am not sure how long it takes being off before I have to unplug and plug back in to make the on/off button (or any of them, for that matter) work again; it seems to vary. Last time I tried it it only took a couple hours, and sometimes it seems sooner than that. Once I had to unplug it to turn it off, too, as the button lights were on but not responding. And, when I thought it fixed itself, it went a couple of times over 12 hours and came right on. It's real inconsistent.

                        I always plug it into a relatively new Belkin Surgemaster, not a real cheapie; I have not tried naked to the wall yet.

                        There are only three caps on the inverter board, and I replaced them with good low ESR caps from my local electronics store (yeah for Tanner Electronics in Farmers Branch Texas!) who is the only place I can still buy open-bin components and caps and have folks who know what the stuff is. I will take it out and photo it too, as the cable from the button or switch board mates with that; BTW, I am pretty savvy about the tiny ribbon cable connector pieces and know how to work them, so I am pretty sure all the cables get put back correctly.

                        I am ready to recap the board, but honestly these caps look good. It is a new old stock board I actually bought from China (way too expensive) because my old board would only light one tube, even after recapping (prob a transistor). So, the revision and part numbers are exactly the same as what was in there. The tech at BenQ could tell me nothing about whether they had any rev's to the board since new, does not have real repair info at all.

                        The unit was made in June, 2005, so I imagine the board I bought is from close to the same date.

                        Boy, any help would be appreciated. I can't do anything with this monitor, can't even give it to someone if they have to unplug/replug, and something will probably deteriorate further if that's what's happening. I'm kind of stuck now that I've spent so much on this monitor.

                        You all are a great bunch to just want to get on this forum and help guys fix their own stuff.

                        I will attach the photos.
                        Tombodude
                        Attached Files

                        Comment


                          #13
                          Re: BenQ V2400W power button quits working after period of shut down until power recy

                          The caps on the power board are:
                          Big one: Elite 150uf 450V
                          (4) 330uf 35V Rubycon YXH T0838
                          (1) 330uf 35V ???(no name) KY
                          (2) 220uf 50V ??(M in a box) NHG
                          (2) 47uf 50V Lelon ???

                          Comment


                            #14
                            Re: BenQ V2400W power button quits working after period of shut down until power recy

                            1) The date code on the power board 080825 tells you it was made in 08/2008/25.

                            2) If CN701 is the connector to the main board, take DC voltage readings for each pin when the monitor is working and not working. If it is easier, measure the pins on the main board side as the backside is facing you (pins 1-12). Report your results.

                            3) It looks like the power board is populated with high quality caps made by Rubycon, United Chemicon (KY) and Panasonic (M). The Lelon caps are suspect, but let's give them the benefit of the doubt for now.

                            4) Post a front side picture of the main board.

                            5) It looks like you replaced some caps on the main board? What brand and series are they?
                            Last edited by retiredcaps; 09-06-2012, 05:10 PM.
                            --- 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


                              #15
                              Re: BenQ V2400W power button quits working after period of shut down until power recy

                              Thanks, I'll get the pic out. So, I should reassemble everything outside the case and turn it on and check the pinouts for dc voltage - where do I put the ground lead if not just grounding it somewhere?

                              Comment


                                #16
                                Re: BenQ V2400W power button quits working after period of shut down until power recy

                                Originally posted by tombodude View Post
                                So, I should reassemble everything outside the case and turn it on and check the pinouts for dc voltage - where do I put the ground lead if not just grounding it somewhere?
                                Assemble and put it back in the case and then use a ground screw for ground. You can take measurements on the backside of the main board.
                                --- 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 ---

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