Page 151 - Testing Electronic Components

Testing Triac

1) First make sure you know the terminals of the triac. If you do not
know, you can always refer to a semiconductor data book or
browse through the internet. Once you have located the terminals,
it is the time to use your analogue meter set to X 1 Ohm or X10
Ohm.

2) Place the red probe to terminal 2 and the black probe to terminal 1.
You should get a high resistance reading.

3) Now, use a screw driver tip to create a momentarily short between
the gate and terminal 2 or you can just move the red probe touching
the gate while the red probe is still on the terminal 2. This short
will cause the triac to turn “ON” and you will see a low resistance
reading at the meter panel and remain low even the gate connection
is broken.

4) Reverse the probes and retest again and you should expect the
same result.

These reading are approximate and may vary with manufacturer or
different specification from the triac, from experienced; any result that
is significantly different would point to a faulty triac. If possible, get
some triac with different specification and measure it to take down their
measurement for future comparison.

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