How do test a transistor?

[DanoNJ]

I have a simple 3 ch controller that worked fine, till the other day. 2 ch will no longer work. It appears the controller uses 3 transistors to aid in the flashing. I'm wondering if 2 of these too a powder on me. Can these be tested in any way?

 

[KeithTarpley]

Greetings,,,

If you have a multimeter, try something like this:

http://www.hobby-hour.com/electronics/testing-semiconductors.php

Or, unsolder and switch a suspect one with the known good one, and test.

Keith