Positive and negative discrimination of ir led ic

Ir LED lamps IC in the welding process, our need to recognize that how to identify the positive and negative of ir led ic, this is particularly important,

The most commonly used method is the use the multimeter to measure. The use of “R * l0k” grades . Because the pressure drop of the ir led is about 3V.The pressure drop of multimeter’battery is 1.5V when we use “R×lk” to measure. Below the tube pressure drop of the ir led. Both positive and reverse access, the ir light-emitting led can not lead, in here the multimeter cannot take be detected work. “R * 1K” grades inscribed with 9V (or 15V) high voltage battery, is higher than the ir led’voltage drop, so it can be used to detect the ir light emitting led. During the detection,the multimeter linked it to the tow-side of ir led ic such as pointer spin to half of multimeter’panle. It is forward access, this time with the black pen (with the inner battery positive terminal) is in contact with the positive electrode; and red pen (with tables inside the battery negative terminal) is in contact with the ir led ic.  then inverted access with pan. The point should not move.
If either positive or reverse access with check’pan, the point of Instructions are not moving or at the end of the deflection of indicator panel, the Infrared led ic has been damaged.