Test with a multimeter

LED

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Now: Forward: red on the long leg

CircuVanta 6000 counts · auto range DCAUTO•)))HOLDFUSE− HOLD LIGHT OFFV⎓V~Ω•)))FmA⎓ mA400 mACOMVΩ Anode (A) 1 A Cathode (K) 2 K
Pin 1: Anode (A) (A) Pin 2: Cathode (K) (K)

Red probe Not connectedBlack probe Not connected

Hold the probe and drag it to the tip of a leg. Tapping works too: first pick the probe, then the leg.

Set the range to diode test.

Measure step by step

An LED is also a diode. In the diode range, in the forward direction, red, yellow and green LEDs glow faintly; that is the easiest sign that they are good. The threshold of blue and white LEDs can be higher than the multimeter’s test voltage: even if they are good you may see OL. Test them on a supply through a series resistor.

  1. 1Forward: red on the long leg
  2. 2Reverse: red on the short leg