Section 1 - How-To Guide:

Learning the Basics of Plasma, LCD, and LED TV Circuit Boards




Introduction

Before getting into how to look for the board number and part number of a TV part, it may be helpful to know what the three major TV types are and the differences between them that are currently being sold in retail stores at present. They are:

Also, it may be helpful to know what the different components are in your TV. In this guide, you will learn the basic differences between the three types of TV's and what kinds of components that each TV type carries. Once you have familiarized yourself with the different types of TV's and various TV components, it will be that much easier in locating the board number and part number of a particular TV component because you will know: 1) what the part is, 2) what it looks like, and 3) where to look on the board for the board number(s) and part number.


Plasma TV's

The most obvious way of telling apart whether a TV is an LCD or a Plasma is whether the TV has a physical sheet of glass that is placed in front of the actual screen itself forming a sort of protective barrier to the fragile screen just beneath it. If your TV has this glass, it is most likely a Plasma TV.

Another way to tell if the TV is a Plasma is to compare its picture quality side to side with an LCD. Typically, older Plasma TV's that are 720p (as opposed to LCD's that are typically 1080p) will show a distinct difference in picture quality, namely, there will be some pixelation. What is pixelation? It's when the picture quality looks "blocky" rather than smooth. However, picture quality is a relative term and it is wrong to assume that Plasma's are always of lower picture quality.

Relative to CRT (cathode-ray tube) TV's, Plasma's are definitely a good few steps above in terms of picture quality. However, compared to LCD's, the difference in quality may or may not be noticeable depending on how much "clarity," "brightness," and "depth" of color matters to an individual. At present, there are, in fact, Plasma TV's currently being sold in retail stores that are 1080p and they are a farcry from the first and second generations of Plasma TV's in terms of clarity, brightness and depth of the colors.

Note: You may be wondering what the little 'p' stands for. It stands for "progressively scanning." You may have also come across the little 'i' in conjunction with 1080. That stands for "interlaced scanning." The main differences between the two is in how they refresh the screen. For our purposes though, it isn't necessary to know how exactly the screen is refreshed. Just know that it is merely a different way of refreshing the screen.


LCD TV's

LCD TV's don't have the characteristic sheet of glass in front of the actual screen that Plasma's are known for. The screen that you see on this TV is the actual screen. It is extremely fragile, thus, it would be advisable not to bring any trauma to the screen, which may likely shorten its lifespan and/or render the screen unviewable.

Secondly, most modern day LCD TV's are, by default, 1080p with the exception of the first and second generation of LCD's and of TV sizes at or below 32". There are, however, some 1st and 2nd generation LCD TV's that are at sizes 32" and below that are 1080p but those are few and far in between and are usually only found in computer monitors. As a general rule, LCD TV's that are larger than 32" are usually 1080p.

Thirdly, one of the most obvious differences between LCD's and Plasma's is the picture quality, namely, the smoothness of the textures and the depth and clarity of the colors. It is also simpler in design, thus, it is lighter than Plasma TV's in terms of weight.


LED TV's

The main difference between LED TV's and LCD TV's is in the backlight. You may have come across several other electrical devices that uses LED lights, such as halogen lamps or the lightbulbs of the taillights in modern day cars. Those are all LED lights. Aside from that, there's virtually no significant difference between LCD TV's and LED TV's.

The design and internal architectures are the same. You can think of an LED TV as an LCD TV but with better lighting or as using a different type of lighting technology to project the image on the screen. It's also more environmentally friendly relative to regular LCD TV's because the backlighting used can be easily recycled, uses less energy to power the TV panel, and is lighter, in terms of weight and construction, relative to LCD TV's.



TV Components

Plasma TV's

Plasma TV's have a series of circuit boards. Every Plasma will have each of the following components:

LCD TV's

LCD TV's also have a series of circuit boards. Every LCD will have each of the following components:

As noted previously, LED TV's are virtually the same as LCD TV's with the exception of its different lighting technology, thus, the components between an LCD TV and an LED TV are virtually the same as well.



Main Board

The easiest way to identify the Main Board is to look for the circuit board with the audio and video inputs and outputs. It is also commonplace to find the tuner, HDMI, USB, and S-video ports all on the same board. There are, however, exceptions to this rule but generally speaking, if you find the board with the audio and video inputs and outputs, it is the Main Board.

The Main Board is sometimes called other names, such as "Motherboard," "Main Unit," "A/V Board," "Signal Board," or "Main Module." For our purposes though, all these different names refer to one and the same thing.

Power Supply Board

The Power Supply Board is usually the biggest and heaviest board found inside the TV and it has all sorts of bulby objects, a series of small to large capacitors, various square block components that look like LED lights with a copper-colored wire wound around a 'wheel' and 2 or more elongated heatsinks. These heatsinks look like a long, rectangular-shaped, metal slab that is soldered to the board or are securely bolted down.

The Power Supply Board is sometimes referred to as the "PSU" which is the acronym name for "Power Supply Unit." On occasions, it is also called the "Power Supply Module." This latter name, however, is rarely used by average, everyday consumers and big-box/discount retailers. It is typically only used between electronics repair technicians and other professionals in this field.

Logic Board

The Logic Board is one of the smallest boards inside the TV and second only to the T-Con Board in terms of size and thickness. It's usually only found in Plasma TV's and it usually has a main CPU and several smaller processing chips scattered throughout the board. This is a very distinctive board in that it is connected to all the other boards. Sometimes, this board is located below the main board enclosed within a metal casing and sometimes it is located above it with or without a metal casing. There's no particular location that this board is usually placed.

This board is sometimes referred to as the "Control Board."

X-Sustain Board

The X-Sustain Board is only found in Plasma TV's and is usually a fairly large board that is similar in size to the Power Supply Board except that it is typically horizontally longer but it isn't unusual to find one that is squarish in shape akin to the shape and size of the Power Supply.

Nevertheless, this board is distinct from the latter in that it doesn't usually have one of those "square box" components. This "square box" component usually has a copper-colored center that looks like a wound up wire around a loop and this can only be seen if the plastic reflective tape on top has been removed. Otherwise, this tape can take various solid colors, such as yellow, green, blue, white, red, or a combination of two colors, with one color on one half and another color on the other half.

On occasions, this component may stand up vertically facing off to the side but typically, it is laid down on its back and if you're staring at it from a bird's eyeview, you will readily see it.

This board is sometimes referred to by other names and abbreviations, such as XSUS, X-SUS, ZSUS, Z-SUS, Z-Sustain, XM, X-Main, Z, Z-Main--all of which refer to one and the same thing.

Y-Sustain Board

Like the X-Sustain Board, the Y-Sustain Board is also only found in Plasma TV's and is usually similar in size to the Power Supply as well. The X and Y-Sustain boards look almost the same in comparison to each other and share almost all the same components as well. The difference between the two lies in what they control internally.

The Y-Sustain Board controls the backlight of the TV Panel in a Plasma and it is like a "positive node" that provides the positive electrical charge that courses through the TV Panel, thus lighting up the screen. The X-Sustain Board merely supports the functions of the Y-Sustain Board and it is like a "negative node" that provides the counter-balancing negative electrical charge to even out the positive charge that is provided by the Y-Sustain Board.

Like the X-Sustain Board, the Y-Sustain Board is sometimes referred to by other names and abbreviations, such as YSUS, Y-SUS, Y-Main--all of which refer to one and the same thing.

Inverter Boards

These boards are usually found along the edges nearest to the TV Panel and are only found in LCD's. It can be found as a single board all by itself in an LCD TV, in pairs, or two pairs. These boards are usually long, thin boards with several square block components called "transformers." However, in smaller TV's, that are between sizes of 19" to 32", it isn't unusual to find an Inverter Board with only one transformer and its size being comparably as small as a Logic Board.

These boards are typically found nearest to the edges on the left and right or top and bottom of the LCD TV and is sometimes referred by its longer name, "Backlight Inverters."

Buffer Boards

Buffer boards are roughly the size and width of the Inverter Boards. They are usually connected to the Y-Sustain Board and usually come in pairs: the Upper Buffer Board and Lower Buffer Board. Technically speaking, there's really only "one" Buffer Board in a Plasma because the Upper and Lower Buffer Boards connect end-to-end and form one singular board. These boards merely support the functions of the Y-Sustain Board.

These boards are sometimes referred to as "Scan Drive" or "Y-Buffers," both of which refer to the same thing but is more commonly called "Buffer Boards."

T-Con Board

The T-Con Board is the smallest board found inside an LCD TV and is usually only found in LCD TV's. Unlike the Logic Boards of Plasma's, which typically have slotted connectors on all four sides, this board only has connectors on two sides of the board, usually on the top and bottom. Other than that minor difference, there is a main CPU and several smaller processing chips scattered throughout the board, just like the Logic Board of Plasma TV's.

The T-Con Board is sometimes referred to other names, such as "Logic Board," "Controller Board," or "Control Board." All these terms refer to one and the same thing.


Go to Section 2 of our How-To Guide