Yea, actually a
triac, usually part number BTA16-600B
When they go, they usually blow in the "on" mode, as in the light is full on. They can go open
circuit, but not too often. I would check a few other things first to make sure they are being told to turn on, such as setting the
DMX to 1 and making sure there is not an active patch on the board that might be masking the channels. Good luck.