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Inverter or CCFL?

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  • Inverter or CCFL?

    Hi, i was recently given a viewsonic 17" LCD Monitor. From what I can tell either the inverter or CCFLs are bad. I can get the Replacement Bulbs and/or inverter from moniserv.com.

    I opened it up (its 2 years out of warranty anyway) and the Inverter PCB looks fine, and the CCFL Bulbs do not look damaged in any way. The wires between the Bulb and LCD look fine as well. I get an image on the screen and if viewed from the right angle you can make out a picture, and the LCD itself is undamaged.

    The bottom CCFLs (it has 4 total, 2 top, and 2 bottom) will briefly ficker at random times when it is on.

    How can I tell which it is?

  • #2
    I'd use a multimeter on the high voltage wires to see if the inverter is supplying any power to the tubes.
    Don't forget to set your multimeter to 600VAC.
    And be careful, those wires bite!
    For Sale: Carputer (CarPC) & RCA Y-Adapter
    Newsflash: Take a look at my unsold stuff above, thanks!
    Up Next: Make an OBD to Serial cable & Redo the "MMI buttons"

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    • #3
      Ok, I'll do that. And i know they bite, I made a taser out of an old CCFL inverter that powered some broken ccfls for a case mod. add a 9v battery and you got a mini cattle-prod. Thanks

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      • #4
        Originally posted by OmegaAvenger
        Hi, i was recently given a viewsonic 17" LCD Monitor. From what I can tell either the inverter or CCFLs are bad. I can get the Replacement Bulbs and/or inverter from moniserv.com.

        I opened it up (its 2 years out of warranty anyway) and the Inverter PCB looks fine, and the CCFL Bulbs do not look damaged in any way. The wires between the Bulb and LCD look fine as well. I get an image on the screen and if viewed from the right angle you can make out a picture, and the LCD itself is undamaged.

        The bottom CCFLs (it has 4 total, 2 top, and 2 bottom) will briefly ficker at random times when it is on.

        How can I tell which it is?
        I think that the chances that *all* four ccfl's broke is a lot lower than a bad inverter. I could see all the bulbs breaking (ie, shattering) from the LCD being dropped/whacked, but that doesn't sound like the case here. If two of them so much as flicker, the glass in them is completely intact, so the only other (common) cause of tube failure would be slow degredation of the electrodes. I find it unlikely that the previous owner held onto a slowly dying LCD so long that all 4 bulbs were completely shot.

        Am I reading you correctly? Top bulbs are completely off, bottom ones just flicker on once in awhile?

        My bets are on the inverter. If not that, then maybe the power supply *to* the inverter. Since it's a desktop LCD, you might not have any DC converter (the inverter might take AC directly), but maybe you can at least trace the power wires and make sure everything's in good shape. I'd stick a multimeter on the input power too.

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