Test with a multimeter

Triac (BT136)

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Now: Between MT1 and MT2

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Pin 1: MT1, pin 1 (mt1) Pin 2: MT2, pin 2 (mt2) Pin 3: Gate, pin 3 (g)

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 Ω (resistance).

Measure step by step

A triac's main path is between MT1 and MT2; the gate, on the other hand, shows a small resistance relative to MT1. A good triac gives OL between MT1 and MT2 in both directions and shows tens of ohms between gate and MT1. A multimeter cannot trigger and hold a triac; this guide only does the soundness check that can be measured. This guide uses the BT136 leg order.

Triacs drive mains loads. Before measuring, disconnect the circuit from the mains and remove the part from the circuit.

  1. 1Between MT1 and MT2
  2. 2Between gate and MT1
  3. 3Between gate and MT2