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Salvaged Circuitry

Adventures in Tinkering

LCD Repair

Let's admit it, LCD screens are great! Especially when your used to a crowded desk with a gigantic CRT monitor taking up most of your work space. The problem is, LCD's are quite expensive, and exponentially increase in price with size and resolution. The best way to get your hands on an LCD, is fixing a broken one! Think about it, if you find or buy a broken LCD and know your way around electronics, you can gain some serious real estate without breaking the bank. Of course, your probably not going to find any studio-grade LCD's in the trash any time soon, but it's good to expand your horizons with a little extra knowledge.

Since this is a general guide to repair LCD's, I will be showing you some different LCD's that were damaged, but repairable. Before you go and start buying every broken LCD's from ebay, consider these two points: -If you find a LCD display where the LCD itself is cracked, and it is quite visible, there is no electronic magic skills that can fix that display. The only thing you can do is purchase a replacement LCD panel. -If you find a LCD display where the LCD panel looks like it has ink splotches inside it (when viewed from an angle almost parallel to the panel), again, you'll have to end up purchasing a replacement LCD panel.

Of course, if the LCD display you find is one you already have and is unrepairable, you might find the digital display board, inverter board and power supply to be of great use.

If you find a LCD panel in an unknown condition, these are some generalizations that can help you diagnose the LCD display: If the monitor you find seems to not display an image from direct view, but shows an image when you turn the lights off and view the screen almost parallel to its surface, the lamp inverter board and or backlight lamps are your problem. Not sure? go ahead and take the lamps out and grab a flashlight and shine it in the slot where the backlights go. Notice you can see the display showing your desktop background more clearly.

If you find an LCD where the picture shows up but there's slight deformities in the image quality, well it's probably the digital display board. the digital display board is responsible for driving the video image from the computer video card signal to the back of the LCD panel. SO if you are seeing random patterns on the display or weird color banding on the display, it's the digital display board that's funky.

If you are seeing black or white pixels where there shouldn't be, that is a sign of dead or "hot" pixels, respectively. That is usually a LCD panel problem, not a digital display board problem. The erroneous pixels come from deformities in the production of the LCD panel itself and show after the monitor has been used for a few months.

A terribly common problem with LCD's today is overheating. Because LCD's are passively cooled (not actively cooled, such as with a fan), they are very easily driven to high temperatures when shoved in a corner of a table, against a wall, or under a shelf. lack of airflow and extended use spell out problems down the line with the LCD. Such problems are the "blinking screen issue" where the display looks fine for a fraction of a second and then just shuts off. This is usually directed toward a overheated digital display board controller chip or a faulty power supply. The reason why it could be a broken power supply is because the backlights turn on for a fraction of a second and then abruptly shut off, showing that they are not receiving enough current or voltage to properly run. If the LCD fails to turn at all, it is most likely a bad power supply. the components in LCD power supply's tend to overheat as they are shoved into smaller and smaller spaces. This is why you see the power boards on LCD's are getting larger over time, if you look at a LCD form 2003 to one from 2007. The components on the power supplies are getting more widely spaced so they take advantage of more passive airflow.