How to measure the quality of LED lights with a multimeter
Let's take a digital multimeter as an example. (1) Select the diode jack and insert the red test lead into the diode port (red hole) and the black test lead into the COM port (black hole). (2) Select the diode gear and set the rotary switch in the middle of the digital multimeter to the diode (beep) gear. (3) Connect the circuit under test to contact the anode of the diode with the red test pen, and contact the cathode of the diode with the black test pen. ①How to distinguish the positive and negative poles of the pin-type LED: the long pin is the positive pole, and the short pin is the negative pole. If the two pins are cut to the same length, you can hold the lamp bead to the light and look at the metal pole inside. The corresponding pin under the small metal pole is the positive pole, and the other end is the negative pole. ②How to identify the positive and negative poles of the SMD LED: the end with a colored line or a missing corner is the negative pole, and the other end is the positive pole. (4) If the observed value and the brightness of the diode are fixed, if the forward resistance value is fixed, there will be a buzzer sound and the lamp bead lights up, and the reverse resistance value tends to infinity, indicating that the diode is normal if the forward resistance value and the reverse resistance value are both tends to infinity, indicating that the diode has a short-circuit fault. If the forward resistance and reverse resistance both tend to 0, it means that the diode has a breakdown short-circuit fault. If the forward resistance and reverse resistance are very small, the diode has been broken down.
