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Viewsonic vx2235 with bad caps

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    #21
    Re: Viewsonic vx2235 with bad caps

    Originally posted by gregmcc View Post
    When I switch the monitor on it flashes on and off for a fraction of a second and I can briefly see the correct grahpics on the screen. Then all goes dark.

    IC200 is a 20 pin chip:
    OZ964GN
    Okay, the flash makes a huge difference on where to look. The flash tells us that most of the circuitry is working.

    I can think 3 possible problems.

    1) One or more of your CCFLs are dying or bad.

    2) One of the inverter transformers is bad.

    3) Something else in the sense circuitry is causing the IC to shutdown the backlights.

    For #1 and #2, see

    https://www.badcaps.net/forum/showthread.php?t=10419

    If it comes down to #3, this will require more effort. Try #1 and #2 first and report your findings.
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    Comment

      #22
      Re: Viewsonic vx2235 with bad caps

      Thanks for the link. Only getting to this now.

      I've checked the transformers. I think they're the transformers. I'm getting completely different readings as mentioned in the link. I've attached pics of the transformers. They are the transformers I'm supposed to measure right?

      I get the following:


      Pin:
      8 9 10 11

      1 2 3 4 5 6 7

      Pin 1-8 1Mohm
      Pin 3-6 1Mohm

      All the other pins are open. I've desoldered the transformers and measured both. They both give the same readings.

      I also dont have a spare LCD so can't test the CCFLs.

      If it worth trying to source another inverter board and trying my luck? Not getting anywhere with this
      Attached Files

      Comment

        #23
        Re: Viewsonic vx2235 with bad caps

        Originally posted by gregmcc View Post
        I've checked the transformers. I think they're the transformers. I'm getting completely different readings as mentioned in the link. I've attached pics of the transformers. They are the transformers I'm supposed to measure right?
        Yes, those are the transformers.

        I get the following:


        Pin:
        8 9 10 11

        1 2 3 4 5 6 7

        Pin 1-8 1Mohm
        Pin 3-6 1Mohm

        All the other pins are open. I've desoldered the transformers and measured both. They both give the same readings.

        I also dont have a spare LCD so can't test the CCFLs.

        If it worth trying to source another inverter board and trying my luck? Not getting anywhere with this
        Those readings are nothing like what I expected. I won't have access to my boards or a multimeter for a couple of days, but 1Mohm for the 2 readings is really high. I can understand one transformer being bad, but 2?

        I'm not as good as PlainBill as identifying which pins are the actual secondaries which is why the instructions are to measure all possible combinations.

        If you can list the part number of the transformer, you might be able to find it at http://www.lcdparts.net/T.aspx . If yes, that site documents which of the pins are secondaries and list the resistance reading you should expect. I would have expected somewhere between 900 ohms and 1600 ohms.
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        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

          #24
          Re: Viewsonic vx2235 with bad caps

          could some one tell me what the value of f200 is, I have same board and replaced caps and f200 is blowen monitor is working but i put jumper wire on for now.

          Comment

            #25
            Re: Viewsonic vx2235 with bad caps

            Originally posted by Mark369 View Post
            could some one tell me what the value of f200 is, I have same board and replaced caps and f200 is blowen monitor is working but i put jumper wire on for now.
            Did the old fuse have a letter stamped on it? Different variations of your board specify a 3A fuse.

            Comment

              #26
              Re: Viewsonic vx2235 with bad caps

              sorry found it 3.3a glass

              Comment

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