Monday, November 29, 2010

Samsung LCD Televisions

Samsung LCD Televisions - What is it with Samsung flat-screen TVs? Since late last year, has been flooded with complaints from consumers who say their Samsung HD TVs overheat, refuse to turn on, power themselves off or simply fizzle off into oblivion. To make matters worse, in most cases, this happens after the one-year warranty has expired.

Samsung isn't saying much about the problem. After repeated inquiries, a company spokeswoman could do no better than this rather tepid response:

"As a first step, we encourage customers who experience any issues with our TVs to call 1-800-SAMSUNG. Our customer service team will fully investigate and discuss each customer’s specific experience so that we can help identify the best resolution to fit each case. Customers’ experiences with our products and service teams are of the utmost importance to us. When we see a problem frequently reoccur, Samsung takes the necessary steps to correct the issue."

Some more helpful guidance comes from the guys who work on dead Samsungs every day. At A+ TV Repair in Southern California, a technician named Phil who asked that his last name not be used said he thinks the Samsung line has been “deliberately under-engineered.”

Samsung LCD Televisions

Plasma Television

A plasma display panel (PDP) is a type of flat panel display common to large TV displays (80 cm/30 in or larger). They are called "plasma" displays because the pixels rely on plasma cells, or what are in essence chambers more commonly known as fluorescent lamps. A panel typically has millions of tiny cells in compartmentalized space between two panels of glass. These compartments, or "bulbs" or "cells", hold a mixture of noble gases and a minuscule amount of mercury. Just as in the fluorescent lamps over an office desk, when the mercury is vaporized and a voltage is applied across the cell, the gas in the cells form a plasma. (A plasma is a collection of particles that respond strongly and collectively to electromagnetic fields or electrical charges, taking the form of gas-like clouds or ion beams.) With flow of electricity (electrons), some of the electrons strike mercury particles as the electrons move through the plasma, momentarily increasing the energy level of the molecule until the excess energy is shed. Mercury sheds the energy as ultraviolet (UV) photons. The UV photons then strike phosphor that is painted on the inside of the cell. When the UV photon strikes a phosphor molecule, it momentarily raises the energy level of an outer orbit electron in the phosphor molecule, moving the electron from a stable to an unstable state; the electron then sheds the excess energy as a photon at a lower energy level than UV light; the lower energy photons are mostly in the infrared range but about 40% are in the visible light range. Thus the input energy is shed as mostly heat (infrared) but also as visible light. Depending on the phosphors used, different colors of visible light can be achieved. Each pixel in a plasma display is made up of three cells comprising the primary colors of visible light. Varying the voltage of the signals to the cells thus allows different perceived colors.

Plasma displays should not be confused with liquid crystal displays (LCDs), another lightweight flat-screen display using very different technology. LCDs may use one or two large fluorescent lamps as a backlight source, but the different colors are controlled by LCD units, which in effect behave as gates that allow or block the passage of light from the backlight to red, green, or blue paint on the front of the LCD panel.