Tip & How-To about Acer Aspire 3680 Laptop
I can only see a very, very faint image of my operating system desktop on the screen.
Diagnosis & Solution
In such cases, the first thing to do is to plug in an external monitor and see if you could get a good image on it. If you get a good image on the external monitor, then this means that the video system is working, but the LCD isn't getting any backlighting. This could be due to either a failing backlight lamp or a failing inverter. The usual culprit is the inverter, especially if you didn't note any strange tinting to the laptop display in recent operation.
The traditional method used by technicians to test inverters is to connect it to a known good backlight lamp of the proper type, and test to see if the inverter could power up the backlight lamp or not. You could also test the inverter by connecting it to a good laptop screen that you might have salvaged from a dead laptop. If the inverter lights up the screen, then the inverter board is good and you are left with a bad backlight lamp as the cause of the problem. Otherwise, it is the inverter which is bad & needs to be replaced.
An alternate method to test the inverter is if you have access to a good quality RMS multi-meter, one that can measure frequency to 50 MHz or 100 MHz, you should be able to get a reading on a functioning inverter without even taking the lid apart. The inverter is normally located below the LCD in models with narrow borders, or to the side if there's an inch or so of plastic bezel on each side of the LCD. By scanning with the multi-meter probes over the plastic along the edge of the screen, you should pick up a strong signal somewhere between 30 KHz and 70 KHz if the inverter is live. If you can't pick up the signal but want to be sure, remove the plastic bezel from around the screen and measure right on the two insulated wires leading to the backlight. If the inverter is functioning, the meter will pick up the signal right through the insulation, since the inverter is putting out a low radio frequency signal.
Most of the time, a bad backlight lamp means that the whole LCD screen needs to be replaced.
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Posted by Mohamed... on
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