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Could A 15″ LCD Monitor Drive A 19″ Backlight?

By on March 31, 2008

There was a 19″ HP LCD Monitor came in for repair and the complaint was display shutdown after “On” for few seconds. From my experience, there are many cases of display shutdown due to defective a backlight. In order for me to confirm whether the backlights are good or not or if it the soucrce of the shutdown problem, i used a 15″ LCD Monitor to test it out since both of the LCD Monitor have the same type of backlight connector.

lcd lamp 

I removed the good working 15″ LCD Monitor backlight connector and use the 19″ LCD Monitor backlight connector to plug it in into the 15″ LCD inverter board. Guess what happen? The display works good and there is no flicker in the 19″ LCD display. I tested on both the top (2 backlights) and the bottom (2 backlights) and the 15″ LCD Monitor didn’t shutdown. This proof the 19″ LCD Monitor backlights have no problem and the display shutdown could be in the inverter board itself. It could be a defective inverter IC or surrounding components.

Although the 19″ LCD Monitor have display after plugged into the 15″ LCD Monitor inverter, the display was not that bright. This mainly due to the output ac voltage from the 15″ LCD inverter was not high enough to drive the 19″ backlight. Hope this repair tips can helps you in your LCD Monitor repair.



  1. sadu

    November 4, 2009 at 9:09 pm

    what is the price of 15" LCD monitor backlight

  2. admin

    November 5, 2009 at 7:13 am

    Hi Sadu,

    Sorry, i do not sell backlight as most of the backlight i got it from junk monitors.


  3. Aaron

    December 26, 2009 at 4:32 pm

    Hello, just another couple of ideas to add to the above article...

    As CCFL lamps age they begin to pull more and more voltage. This increase in voltage continues throughout the life of the lamp until eventually the inverter can not produce enough voltage to keep the lamp lit. Most inverters have a safe mode..meaning once the lamps demand a certain voltage requirement the inverter
    shuts off to protect itself from burning out (loss of transformer caps etc..).

    The symptoms described above...are most commonly attributed to aged backlights (CCFL lamps). Upon start up the inverter gives a burst of high voltage (starting voltage) which momentarily ignites the lamps but as soon as the inverter drops down to running voltage the output potential of the inverter is not high enough to sustain the lamps and the inverter typically reads this as an open condition and shuts off (self-protect mode).

    Theoretically speaking, as long as you provide enough voltage while maintaining the required amperage (typically between 5-7 mA) the lamps will continue to run. It is our experience that by simply changing the backlights (readily available at this takes care of the problem more than 95% of the time. It is a shame so many people waste money on a new inverter when most often they are not the problem.

  4. admin

    December 27, 2009 at 9:40 am


    Thanks for the sharing and i have put up your website into my blog.


  5. Rolf J. Cousin

    December 1, 2010 at 7:32 am

    Dear Service Support

    we need a new distributor for LCD Back-Light tube:
    LM356-17 for LCD Display

    Can you help us above? we need up to 500 piece.


    Rolf J. Cousin

  6. admin

    December 1, 2010 at 10:26 am

    HI Rolf,

    Sorry, i do not have contact on this area.



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