LG W2452V Tear-Down And Repair
Disassembling power bars is good clean fun, but let's try something different today: how about tearing down and repairing an LCD display!
An Ailing Friend
One of my pet peeves about consumer electronics is how they often seem to be engineered to fail shortly after the warranty expires.
This is my six-year-old LG W2452V. Just over two years from purchase, it started having issues with waking up from standby. So I opened it up and found two leaky capacitors on the 5V output, along with slightly bulged caps on the 24V rail. I only replaced the 5V caps since I didn't have suitable replacements for the other ones. Put back together, everything was fine again until a few months ago when failures to wake up started cropping up again. That was my cue to go back in and finish the repair.
Getting The Bezel Off
This part requires considerably more patience, finesse and force. The bezel's snaps are what prevent the LCD panel from falling out of its enclosure, so you want to avoid breaking them as much as possible. Here, I used one of these reward cards I always forget to use as a wedge to pry hooks off.
The point card's plastic is soft, which helps minimize cosmetic damage. Cleaning the clingy, stringy plastic residue that gets scraped off the card can be messy though.
If you are lucky getting the snaps to come apart, you'll see the result on the left: a hook living to snap another day. If you are less fortunate, you end up with the result pictured on the right, where part of the hook broke off. Corners are the most difficult; three perpendicular planes meet together, making the enclosure much stiffer near them.
There were 20 snaps around the bezel, and three of the four I broke were in corners. Two of these casualties were from my first repair.
Behind Bezel #1
Aside from its cosmetic function, the bezel also hosts part of the power button, the snap holes for the bottom trim and structural reinforcements around the snap notches to ensure the LCD does not accidentally fall off. Breaking too many of these will force you to use duct tape for reassembly.
If readers ask nicely, I may do a picture story of my first LCD monitor “repair” (an older LG). The display seemed completely dead by the time I decided to have a look, so I did not feel like sparing much patience for it.
With the front bezel out of the way, flip the chassis and the panel simply falls out. If you take an LCD apart, you need to remember to support it adequately as you lift the rear cover up. Also keep an eye open for any cables that might require unplugging, such as the audio and button harness pictured here.
With the LCD and electronics bay out of the way, we are left with an almost bare housing. Only the buttons, power switch and audio jack PCBs remain.
Since the panel accounts for about half of this screen's total weight, the chassis could have used extra stiffening around the anchor's attachment point and along the bottom. As it is, it takes about ten seconds to settle after a mild sideways nudge or table shake. My Dell screen settles from worse nudges within a second. Weighing less than half as much thanks to LED back-lighting likely helps.
The Audio PCB
From the looks of it, the 3.5mm audio output board is also intended to serve audio input and possibly one other function. As implemented, it only features an Anpec APA2068 2W stereo amplifier with 32-step volume control and over a dozen passive support components. Based on what I can see, there is no option in the monitor's UI to access the amplifier's volume setting, which means the firmware must use a fixed value.
The Navigation Button PCB
For ease of assembly, instead of using individual plastic buttons, LG molded the buttons as a single piece with the PCB cage using S-shaped strips to hold buttons in position over their respective switches. Since each shaft is of a slightly different length to match the chassis' curve, this eliminates the hassle of ensuring individual button pieces are inserted in the correct order.
The Power Switch PCB
There is not a lot to see here: one switch and a dual-LED (amber and blue) package. But the PCB does have provisions for two more LED packages. LG must have decided that three LEDs were too expensive or distracting. One LED is just bright enough for me, so no complaint here.
The Electronics Tray
This steel tray holds the display controller interface, power supply and Cold-Cathode Fluorescent Lamp (CCFL) inverters. It is held onto the LCD's back by a few pieces of metalized tape.
The base anchor screws into that metal piece on the bottom, taking some load off the plastic frame. There should also be a shield over the CCFL wires on the left, but I forgot to put it back on before taking this picture.