How to test LDR (Light Dependent Resistance)

LDR (light dependent resistance) can be very easily tested by using a digital multimeter. We all know that the resistance of an LDR varies according to the light falling on it. At bright light, the LDR resistance will be around 500Ohms and at darkness the resistance will be around 200K. For a proper diagnosis we need to measure the resistance of the LDR at bright light and at darkness.



Test1.

Keep the multimeter at Ohms mode. The LDR must be subjected to a bright light source (day light is enough).Connect the LDR leads to the multimeter terminals as shown in the figure. Now the multimeter will show a low resistance reading around 500 Ohms.



Test2.

Keep the multimeter at Ohms mode. The LDR must be subjected to darkness by covering it with an opaque paper. Connect the LDR leads to the multimeter terminals as shown in the figure. Now the multimeter will show a high resistance reading around 200K.

Click here to learn more:http://www.circuitstoday.com/how-to-test-an-ldr

About Electrolytic Capacitor

Capacitors articles:http://www.ezinstructions.com/badcapacitors.pdf

A 300-W, Universal Input, Isolated PFC Power Supply for LCD TV

This guide documents a low-profile power supply that is suitable for powering LCD TVs or other flat screen


applications. The power supply accepts a universal AC line-input voltage (85 VRMS to 265 VRMS), and produces

an output voltage of 24-VDC for loads up to 12 A (288 W).

The requirements for a flat-panel display include a physical profile and the ability to operate from the ac-line input

at close to unity power factor. Therefore a flat-panel display application demands that an internal power supply be

thin so as to fit behind the screen inside the TV case, and comply with the power quality requirements defined in

the IEC standard, 61000-3-2. In addition, the combination of a tight physical package and the desire to meet

Energy Star® guidelines requires that the design also demonstrates very high efficiency. Described herein is a

practical design that uses standard components. It achieves the requirements using a traditional two-stage power

converter topology along with state-of-the-art power circuit control methods. The first stage is an interleaved,

transition-mode, power factor correcting (PFC) boost pre-regulator. This is followed by an isolated LLC seriesresonant

DC-DC main converter.

The design takes advantage of three integrated circuit (IC) power controllers. The PFC pre-regulator stage is

controlled by the UCC28061, a dual-phase, interleaved, transition-mode PFC controller. The resonant LLC

converter uses the UCC25600; a low-cost 8-pin controller. The third IC is the UCC2813D-4. This is used to

control a small 5-W flyback converter that provides a bias supply voltage. The bias supply is optional. It is

provided for convenience so that the circuit can be demonstrated without the need for a bench supply.
 
Click here for details: http://focus.ti.com/lit/an/sluu341b/sluu341b.pdf
 

Diode Store

If you are looking for diode visit this site: http://www.diotec-usa.com/

LCD TV SERVICE MANUAL

I f you want a free lcd tv service manual click here: http://www.fixdevice.com/smanuals/cat/lcd_tvs.html

SMD Equivalent

If you are looking for the informations for SMD equivalent. Click here: http://www.lcdtvrepair.us/equismd.php

Testing N- Channel Fet using Digital Volt Meter

http://www.standardtestequipment.com/power-mosfet/

Analog Microchip

Does Your Design Require Low Power Analog?

Microchip offers a broad portfolio of low power analog products that support a wide variety of applications. With over 500 unique stand-alone analog products covering thermal management, power management, battery management, mixed-signal, linear, interface and safety and security.
Click the link here: http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=79&redirects=analog

Inormation About FET(Field Effect Transistor

Large percentage of power supply failure has to do with Fet which switch the power in primary section and it is important to know the specification of Fet you are trying to replaced incase if you cannot find the original part number. Here is an article regarding FET information written by sir jestine yong - electronic specialist.Click the link here: http://www.electronicrepairguide.com/Mosfet.html

Some LCD Monitor Repair

http://camericomputers.wordpress.com/2010/12/19/samsung-920nw/

Short Finder

 

http://www.nextag.com/short-circuit-finder/compare-html

Magnavox LCD TV Repair

Some LCD and Plasma Tv Repair Tips

http://plasmalcdtvrepair.rankwell.net/search/label/LCD%20Repair%20Tips

Free Some Lcd Tv Manual

http://www.tv.quuq.org/index.php?ind=downloads