Tuesday, January 11, 2011

How to repair LCD TVs


"Troubleshooting and Repairing LCD TVs"
If you are interested in repairing LCD TVs then click here to check out the top selling LCD TV Repair Guide.
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You may also be interested in Kent Liew's LCD TV Repair Membership Site. This is a great place to get training manuals, service manuals, schematics and more. Click here to read more.


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Remember to visit http://www.preher-tech.com/

How To Repair SMPS(Switch Mode Power Supply)



Had to mention this book again, it is one of my favorite books written by Jestine Yong.

This guide is a must have for anyone who is in the electronics repair field or who is trying to impove their electronics troubleshooting an repair skills. This 271 page guide will teach you all you need to know about Switch Mode Power Supplies and how to troubleshoot and repair them. Switch mode power supplies are used in most consumer electronics today and are the most common cause of failure for all types of electronics devices.


Click here to read more about the ebook "Troubleshooting and Repairing Switch Mode Power Supplies".

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Thermistors


A thermistor is a type of resistor whose resistance varies significantly (more than in standard resistors) with temperature. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.
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Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range [usually −90 °C to 130 °C].
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PTC thermistors can be used as current-limiting devices for circuit protection, as replacements for fuses. Current through the device causes a small amount of resistive heating. If the current is large enough to generate more heat than the device can lose to its surroundings, the device heats up, causing its resistance to increase, and therefore causing even more heating. This creates a self-reinforcing effect that drives the resistance upwards, reducing the current and voltage available to the device.
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PTC thermistors are used as timers in the degaussing coil circuit of most CRT displays and televisions. When the display unit is initially switched on, current flows through the thermistor and degaussing coil. The coil and thermistor are intentionally sized so that the current flow will heat the thermistor to the point that the degaussing coil shuts off in under a second. For effective degaussing, it is necessary that the magnitude of the alternating magnetic field produced by the degaussing coil decreases smoothly and continuously, rather than sharply switching off or decreasing in steps; the PTC thermistor accomplishes this naturally as it heats up. A degaussing circuit using a PTC thermistor is simple, reliable (for its simplicity), and inexpensive.
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NTC thermistors are used as resistance thermometers in low-temperature measurements of the order of 10 K.
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NTC thermistors can be used as inrush-current limiting devices in power supply circuits. They present a higher resistance initially which prevents large currents from flowing at turn-on, and then heat up and become much lower resistance to allow higher current flow during normal operation. These thermistors are usually much larger than measuring type thermistors, and are purposely designed for this application.
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NTC thermistors are regularly used in automotive applications. For example, they monitor things like coolant temperature and/or oil temperature inside the engine and provide data to the ECU and, indirectly, to the dashboard.
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NTC thermistors can be also used to monitor the temperature of an incubator.
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Thermistors are also commonly used in modern digital thermostats and to monitor the temperature of battery packs while charging.
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Remember to visit www.preher-tech.com