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Viewsonic VA902b black display, solid green light.. replaced cap..

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    #1

    Viewsonic VA902b black display, solid green light.. replaced cap..

    Hey guys,

    My Viewsonic VA902b is having an issue. The screen wouldn't turn on one morning and I figured I'd check it out. It was very briefly and dimmly turning on for a seconds then going black with a solid green light.

    I opened it up, noticed cap c808 (1000 uF 25v) was bulging. Today I went and picked up a new 1000 uF 25v cap and replaced it. After plugging everything back in and plugging the power supply into the wall I tried to hit the power button, nothing happened.

    Took it apart again, checked all the plugs and wires, put it back together. Again plugged into the wall and tried to turn it on. Nothing happens. A few seconds later I hear an incredibly loud "POP!". Apart with it again, only to find the cap I just soldered into place had completely exploded.

    Any ideas on how to diagnose this? Was it a bad cap, or is there more likely another issues leading to this cap failing? Hope you guys can help.

    Thanks in advance.
    Last edited by steevz; 11-10-2010, 09:55 PM.
    Tags: None
    #2
    Re: Viewsonic VA902b black display, solid green light.. replaced cap..

    Originally posted by steevz View Post
    Took it apart again, checked all the plugs and wires, put it back together. Again plugged into the wall and tried to turn it on. Nothing happens. A few seconds later I hear an incredibly loud "POP!". Apart with it again, only to find the cap I just soldered into place had completely exploded.
    You might/probably put it in backwards? Caps have a positive and negative.
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      #3
      Re: Viewsonic VA902b black display, solid green light.. replaced cap..

      Agreed, probably installed backwards. That will definitely wake you up.
      36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

      Comment

        #4
        Re: Viewsonic VA902b black display, solid green light.. replaced cap..

        I thought there was as I saw a positive side on the board. The cap was all black with a gold stripe on the one side. I thought the stripe would have been positive. Am I wrong?

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          #5
          Re: Viewsonic VA902b black display, solid green light.. replaced cap..

          Depends on the manufacturer, but stripe is usually negative as far as I've seen.

          Edit: What make/series cap are you putting in as a replacement?

          Comment

            #6
            Re: Viewsonic VA902b black display, solid green light.. replaced cap..

            Unsure. Here are some pics. Guess I read it wrong because the boards positive looks goldish and negative looks black.
            Attached Files
            Last edited by steevz; 11-10-2010, 11:17 PM.

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              #7
              Re: Viewsonic VA902b black display, solid green light.. replaced cap..

              Originally posted by steevz View Post
              Unsure. Here are some pics. Guess I read it wrong because the boards positive looks goldish and negative looks black.
              A number of points.

              1) Please Do not post pictures inline as it slows down everything. Use manage attachments.

              2) It is definitely backwards. Take pictures before removing caps so you remember what they look like and where they came from.

              3) Caps should fit flush against the board.

              4) See the following on how to recap ... (note section 7.3)

              https://www.badcaps.net/forum/showthread.php?t=485
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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

                #8
                Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                Thanks a lot for your help. I'll put a new one in and let you guys know the out come. Great forum btw!

                Comment

                  #9
                  Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                  Retiredcaps got it right. Just to explain a bit, see the marked up attachments. The circle on the stripe indicates the negative side. It's not very obvious unless you're looking for it. In the other marked up photo, the "M" inside a square is the symbol for Matsushita (now Panasonic), and the "FM" is the series of the cap. The red square indicates negative on the PCB itself, but again this depends on the manufacturer. There is discussion elsewhere on this board where the dark side of the circle indicates positive. The only real way to be sure is to reference how the original cap was installed (for future reference).

                  As a side note, where on earth are you able to buy Panasonic FM's from a storefront? Do you live around the corner from Digikey or Mouser? LOL
                  Attached Files

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                    #10
                    Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                    Lol, no I live in Vancouver, BC. There is a store called Main Electronics (http://www.mainelectronics.com/) and you can buy almost anything to do with electronics.

                    So I replaced the cap with a new one, monitor turns on and doesn't dim or go black anymore but the screen looks all fuzzy. It's not the resolution or refresh rate. Ideas?

                    Comment

                      #11
                      Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                      Originally posted by steevz View Post
                      Lol, no I live in Vancouver, BC. There is a store called Main Electronics (http://www.mainelectronics.com/) and you can buy almost anything to do with electronics.
                      I'm jealous. I was in our "best" place in Calgary the other day getting some stuff. I asked if they sold good quality low ESR caps, the guy said, sure we have top quality caps.

                      He came back with G-Luxons
                      36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

                      Comment

                        #12
                        Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                        Any ideas on why the screen would go fuzzy looking after reinstalling the new cap and powering on? Could the cap popping from installing it backwards have damaged anything else?

                        Comment

                          #13
                          Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                          Originally posted by steevz View Post
                          Lol, no I live in Vancouver, BC. There is a store called Main Electronics (http://www.mainelectronics.com/) and you can buy almost anything to do with electronics.
                          That's awesome!

                          Originally posted by steevz View Post
                          So I replaced the cap with a new one, monitor turns on and doesn't dim or go black anymore but the screen looks all fuzzy. It's not the resolution or refresh rate. Ideas?
                          Have you double checked all of your cable connections (especially the one between the main board and panel)? Need pics to see what's going on, please.

                          Comment

                            #14
                            Re: Viewsonic VA902b black display, solid green light.. replaced cap..

                            Heh, took it apart again, checked all connections and put it back together. This time I put it into it's case before trying it instead of stacking everything on top of one another and it works perfect.

                            There are 3 complete rows of stuck pixels across the bottom of the screen from it falling about 6 inches onto it's back from awhile ago, is that possible to get rid of?

                            So I take it the Panasonic caps are of good quality?

                            Edit: Oh yeah, Thanks a lot for all your help guys! This forum is a great resource that I will be using often, glad to be here.

                            Edit... again: About the 3 rows of stuck pixels, they go across the bottom of the screen and they aren't dead because they will change color but never match the image on the screen.

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