How to Test LED (Find Bad LED)

LED:
             A light-emitting diode (LED) is a semiconductor device that emits visible light when an electric current passes through it. LED is basically just a specialised type of diode as they have very similar electrical characteristics to a PN junction diode.This means that an LED will pass current in its forward direction but block the flow of current in the reverse direction.it is a two-terminal semiconducter device, those pins are labeled anode(A) and cathode(K). now, i will show how to check LED using multimeter.

method 1: 

• Required Parts: Digital Multimeter, 5mm LED
• First turn ON digital multimeter and select Diode mode.
• Connect the test leads to the LED terminals(Red probe-LED anode pin,Block probe-LED Cathode pin). Keep test leads connected for a forward  direction.
• If the LED is ON (the LED is good), else the LED is OFF(the LED is bad)
• Multimeter Displayed value is between 1600 and 2000 (the LED is good).

Note:

• Connect the test leads to the LED terminals(Red probe-LED anode pin,Block probe-LED Cathode pin). Keep test leads connected for a reverse direction.
• the LED is not Glow.

method 2:

• Required Parts: Digital Multimeter, 5mm LED
• First turn ON digital multimeter and select Resistance mode and Select 200 Ohm.
• Connect the test leads to the LED terminals(Red probe-LED anode pin,Block probe-LED Cathode pin). Keep test leads connected for a forward  direction.
• If the LED is ON (the LED is good), else the LED is OFF(the LED is bad)

method 3:

• Required Parts: 5mm LED, 1k Resistor, 9V Battery or power supply, pushbutton 
• when switch is press.. if LED is ON (the LED is good), else LED is OFF (the LED is bad).

Note:

• if connect 9v battery directly to LED, the LED is will burn(damage). pls use resistor.

Applicaion:

• Indication
• LED Dot Matrix Disply