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LG W2452V 24-Inch Monitor Tear-Down And Repair

CCFL Connections

Here are those CCFL power connections with the shield on and off. If you ever pop one of these open and need to do live testing on it, keep in mind that CCFL lamps may have start-up or “striking” voltages in the neighborhood of 3kV. That's enough for a nasty zap or potentially ruined test equipment.

Lifting The Tray

When you are ready to pop the electronics bay off the LCD's back, be mindful of the LVDS cable connecting the panel to the display controller. The wires are thin and the end connector is a thin low-force affair with tiny locking hooks.

And When I Say Tiny...

The only things between you and this connector coming loose from a fair shake are two tiny hooks about half a millimeter tall, which retract when the levers are squeezed in. These won't respond well to getting accidentally yanked out. The wires themselves won't tolerate much abuse either.

Behind The Looking Glass

Here is the display panel liberated from the electronics bay. The CCFL power cables are flapping in the breeze along the left edge, and there is a small PCB hidden behind the perforated shielded area near the top. Practically all of the LCD's rear surface area is covered with a thin sheet of stainless steel to shield the electronics and CCFLs from each other. It may (or not) double as a reflector-diffuser for the backlight, but I have no intention of finding out before the lamps die.

Keep On Trucking

This board has two functions. On the left, we have a TI TPS65165 LCD bias regulator that provides the three voltages needed by the panel driver itself. And on the right, hidden under a thick thermal pad, is some sort of LVDS repeater. Nearly all unused space on this board is filled with via stitching to help disperse heat and noise.

At the bottom, you can see the flat-flex cable start on its way towards the panel's controller, covered with reinforcing tape to protect it from damage until it disappears under the steel sheet.

Inside The Bay

Detached from the display panel, the electronics bay can be flipped over. From the left, we see the CCFL inverter, the power supply and the display controller boards. The tray's top and bottom edges are lined with EMI gasket strips. There is not much wasted space in here.

The Inverter Board

The LCD's six CCFL tubes are powered by three transformers with two secondary windings each. All three of them are driven in parallel by a full bridge of Anpec APM4008 N-FETs controlled by an MPS MP1038 CCFL controller. Since half of the board is high-voltage, it is covered by a glued-down plastic sheet on both sides to prevent arcing to the metal chassis. Three Sam Young NXH 35V 220µF caps are bent over into PCB cut-outs and still appear to be in mint condition after six years of frequent use.

No problem so far; everything still looks as good as new.

Outsourcing

It looks like LG grabbed an off-the-shelf CCFL inverter from Frontek Co. Information on the company and its products is sparse, and the website listed on the PCB appears to be gone. The date code, just below the transformer, identifies the PCB as manufactured during the 13th week of 2008, which makes it a month shy of seven years old at tear-down time.

Further below the transformer, you can see three groups of components (resistors, capacitors and diodes) with traces running over to the high-voltage side. There is more of the same going on at the other board end. What do you suppose those might be for?

The Display Control Board

From the left, we have the HDMI, DVI and VGA inputs. DVI and HDMI pass through a signal switch before reaching the display controller IC. The small IC surrounded by caps is the DAC feeding the audio output jack, while the right third of the board contains nothing noteworthy aside from two DRAM chips and the LVDS connector.

I scratched my head for a few seconds when I noticed the speaker near the bottom-left. But then I remembered that turning off UI sounds (and the start-up jingle by extension) was one of the first things I did after turning the display on for the first time.

Quick Look From Behind

Before proceeding with a more detailed tour of the board, let's take quick lookat its back. Like many surface mount boards, the majority of interesting components are on top, while the bottom hosts mostly passive parts that wouldn't fit up there. In this case, you'll mostly find power decoupling caps. Light-brown flux residue is present all over the board.

If you didn't already guess, the areas with solder strips are simply heat spreaders for two of the linear regulators and the display controller itself. All power on this board appears to come from linear regulators.

Daniel Sauvageau is a Contributing Writer for Tom's Hardware US. He’s known for his feature tear-downs of components and peripherals.