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Viewsonic VE710b Power on black screen

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    #81
    Re: Viewsonic VE710b Power on black screen

    The vga cable have a ground connector to a screw of the mainboard (not connected right now). Could be this important?

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      #82
      Re: Viewsonic VE710b Power on black screen

      Originally posted by Guti904 View Post
      The vga cable have a ground connector to a screw of the mainboard (not connected right now). Could be this important?
      When we are doing remote troubleshooting, I have no idea what you are looking at. Thus, clear focused pictures are always a good idea.
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        #83
        Re: Viewsonic VE710b Power on black screen

        I'm taking about the connector from the mainboard that ends in a DB9 blue connector (VGA). The connector has a ground cable. More pics.
        Attached Files

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          #84
          Re: Viewsonic VE710b Power on black screen

          Originally posted by retiredcaps View Post
          Check and reseat all your connectors whether you touched them or not. Always plug in a source (i.e. computer display your favourite wallpaper).
          I put back all the connectors and everything looks worse now including the right side of the screen...

          Comment

            #85
            Re: Viewsonic VE710b Power on black screen

            Originally posted by Guti904 View Post
            Hi guys, after search a lot, I found the C5707 transistor, I´ve replaced the two transistors 2 minutes ago, and I tested the power board with the mainboard and the panel board. I power on and the green power led turns on, then the backlights power on about one second and power off and after that power led change from green to ambar and remains in that status. My question is, without the screen connected, it's a normal behaviour or the backlights must be always on and the power led must remain green?
            The reading of both C5707 between leg 1 and 2 is almost 8V when the backlights is on and falls to 0 when turns off.
            If I remember correctly with this type of power board (BenQ design) there is also a small black fuse labeled: BEL 3A 125V http://www.digikey.com/product-detai...1017-ND/614969 I have actually seen a board with two of these fuses and a Transistor Labeled FU9024N http://www.digikey.com/product-detai...024N-ND/358230 I think there are two of these on that board also. I understand that all of these need to be replaced if you are replacing the C5705s. Hope this helps.
            Have you ever stopped to think and then forget to start thinking again?

            As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

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              #86
              Re: Viewsonic VE710b Power on black screen

              Originally posted by killian6pk View Post
              If I remember correctly with this type of power board (BenQ design) there is also a small black fuse labeled: BEL 3A 125V http://www.digikey.com/product-detai...1017-ND/614969 I have actually seen a board with two of these fuses and a Transistor Labeled FU9024N http://www.digikey.com/product-detai...024N-ND/358230 I think there are two of these on that board also. I understand that all of these need to be replaced if you are replacing the C5705s. Hope this helps.
              I think inverter is working ok with the replacing of the two c5707 (with the source connected now the image appears). The half screen image may be caused by a faulty t-con (mainboard) or a faulty screen (COF). I'm right?

              Comment

                #87
                Re: Viewsonic VE710b Power on black screen

                it happend on back lamp driver circuit issu replace the ccfl driver transformer ocilator trancistor i think its a c5707 x 4 and .22uf 200v x2 replace this parts and try 100%

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                  #88
                  Re: Viewsonic VE710b Power on black screen

                  replace ur lcd display,100%

                  Comment

                    #89
                    Re: Viewsonic VE710b Power on black screen

                    Originally posted by etecnics View Post
                    replace ur lcd display,100%
                    I replaced 2 of the 4 c5706 transistors. Now backlights are working but i've half screen. So, I must to try something new, or the lcd must be damaged, maybe when the power board failed it damage the lcd cof (chip-on-film)? I must stop trying to fix this, and the solution is to replace the entire lcd screen?

                    Comment

                      #90
                      Re: Viewsonic VE710b Power on black screen

                      Originally posted by Guti904 View Post
                      I replaced 2 of the 4 c5706 transistors. Now backlights are working but i've half screen. So, I must to try something new, or the lcd must be damaged, maybe when the power board failed it damage the lcd cof (chip-on-film)? I must stop trying to fix this, and the solution is to replace the entire lcd screen?
                      Why didn't you replace all 4 of the C5707s? Usually when one or more go bad they all go bad or will go bad just after you replace one or two and then power back up again. You need to replace the two that you did not replace the first time.
                      Have you ever stopped to think and then forget to start thinking again?

                      As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

                      Comment

                        #91
                        Re: Viewsonic VE710b Power on black screen

                        Ok, but i'm still wonder if half screen behavior can be due to inverter problem...

                        Comment

                          #92
                          Re: Viewsonic VE710b Power on black screen

                          The two resistances near the c5707s are shorted also...so I think I must to change everything to leave the power board ok, but I'm concerned about the half screen image...

                          Comment

                            #93
                            Re: Viewsonic VE710b Power on black screen

                            Originally posted by Guti904 View Post
                            The two resistances near the c5707s are shorted also...so I think I must to change everything to leave the power board ok, but I'm concerned about the half screen image...
                            Get the components replaced, resistors, remaining 2 C5707s and then if you are still having that problem it will be easier tracing it down knowing those problems have been fixed. Also did you look to see if your board has the FU9024N Transistors. I have repaired 2 Dells, A Viewsonic like yours and I believe it was a Gateway that all had the same parts. When I was repairing the Dells the thinking at that time was to replace all of those components. I don't know if that has changed, but I will bet the same advice is still good. Oh and one other I repaired with this board was a BenQ. Still replaced all those transistors.
                            Have you ever stopped to think and then forget to start thinking again?

                            As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

                            Comment

                              #94
                              Re: Viewsonic VE710b Power on black screen

                              One other thing when you are changing the C5707s are you paying attention to how the old ones came out. I am not sure it matters, but the orientation might be important. I would make a note on each one that you remove whether it faced in or out with respect to the capacitor.
                              Have you ever stopped to think and then forget to start thinking again?

                              As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

                              Comment

                                #95
                                Re: Viewsonic VE710b Power on black screen

                                Originally posted by killian6pk View Post
                                I am not sure it matters, but the orientation might be important.
                                It matters!!
                                --- 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

                                  #96
                                  Re: Viewsonic VE710b Power on black screen

                                  I read another post in the forum and say it can be a problem with the cable going to the t-con or that it's damaged. If backlights are working ok right now, I must not leave out the PSU and look elsewhere?

                                  Comment

                                    #97
                                    Re: Viewsonic VE710b Power on black screen

                                    Any idea?

                                    Comment

                                      #98
                                      Re: Viewsonic VE710b Power on black screen

                                      The resisitors you mention are probably not short, resistors of this type do not go short, and no doubt, you are reading them in circuit, which is causing the anomaly.The fault now that you finally changed the transistors, is more than likely to be the LCD panel itself.

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