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    #1

    Problem with Viewsonic VA1912 Lcd

    My Viewsonic monitor is about 3 years old and has been ok until recently. When I switch the unit on it works fine for 10 to 15 minutes then switches off completely,the power LED is off. After a while the power Led comes back on and the monitor works ok for several minutes and then switches off again, This cycle just repeats and if I disconnect the pc it repeats with the no signal screen. I have stripped out the power/inverter board and there are no obvious signs,the caps all look pristine. The power board is a Delta(no model no) and the monitor is by CHI MEI model A190A2-HD1.
    I have been looking through the forums but I haven't found similar symptoms to mine. It seems likely that whatever is causing the problem is overheating which shuts the power off and then cooling off which allows the power to turn on again. Do caps fail in this way or should I be looking for resistors which can't handle the power.
    Sorry for the long post,I hope you can point me in the right direction.
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    #2
    Re: Problem with Viewsonic VA1912 Lcd

    1) Post pictures of your boards using the manage attachments button so the picture is hosted here.

    We want clear focused pictures with the following composition as shown in

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

    Please do NOT post pictures inline.

    2) Try running the monitor with brightness and contrast at 25/25. Most monitors default to 90/70. Does the monitor stay on longer?

    3) Try running the monitor with a fan for cooling. Does the monitor stay on longer?

    4) Look for suspect solder joints as per

    http://workmanship.nasa.gov/lib/insp...uirements.html
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      #3
      Re: Problem with Viewsonic VA1912 Lcd

      HI Retired Caps, Thanks for the suggestions,I will have to reassemble the monitor to try them out. I have checked for bad soldered joints but I can't find any. Meanwhile here are the photos you requested
      Attached Files

      Comment

        #4
        Re: Problem with Viewsonic VA1912 Lcd

        Originally posted by Ancientwhiz View Post
        the caps all look pristine.
        Those are Capxon brand on the power board. Capxon is probably one of the worst manufacturers of caps.

        Capacitors (C designation on the PCB board) die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bloated in order to bad. They can be out of tolerance uF (a 1000uF measures 20uF) and/or have high ESR (ohm). A multimeter will be insufficient to test for ESR. For that you need an ESR tester which costs between $50 and $300.

        Having said all that, we mainly see bloated Capxon caps when they die. So right now, it is too early to say the Capxon caps are at fault, but we can't disregard their reputation either.

        Right now, try the other suggestions first.
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          #5
          Re: Problem with Viewsonic VA1912 Lcd

          tried the monitor contrast/brightness at 25/25 and it was several hours until the first shutdown and then the intervals between shutdowns were much longer. Tried the fan but it made no noticeable difference. I would appreciate any more suggestions you might have

          Comment

            #6
            Re: Problem with Viewsonic VA1912 Lcd

            Originally posted by Ancientwhiz View Post
            tried the monitor contrast/brightness at 25/25 and it was several hours until the first shutdown and then the intervals between shutdowns were much longer.
            This sounds like a similar problem I had. With brightness/contrast set to 90/75, it would power off in 20 minutes and if you turned it back on right away, it would go 2 seconds to black. Lowering to 25/25 let it stay on for hours.

            In my case because I had 2 identical monitors at the time, I was able to determine that the problem was with the ccfls and/or its wiring. Since it was a 17 inch monitor that was made in 2003, I didn't take it apart to see which ccfl or wiring was at fault. It is my "test" monitor for a lot of things so I don't need it working properly for my needs.

            You are looking for something like ...

            http://s807.photobucket.com/albums/y...klight%20lamp/
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            Comment

              #7
              Re: Problem with Viewsonic VA1912 Lcd

              How were you able to determine that it was a ccfl problem?

              Comment

                #8
                Re: Problem with Viewsonic VA1912 Lcd

                Originally posted by Ancientwhiz View Post
                How were you able to determine that it was a ccfl problem?
                2 identical monitors. I was able to swap parts.
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                Comment

                  #9
                  Re: Problem with Viewsonic VA1912 Lcd

                  can you give a bit more detail on the parts swap,was it the inverter board? Are the inverter and power boards separate on the 17" viewsonic?

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