How to check TRIAC?

My vacuum cleaner is not working, when I checked it I found electronic circuit used to vary the speed. I checked all the components but a Triac ( BTA12600B ) . I need to know how to check it.

On its gate I found a diode written on the PCB D1 with no any other identification just ST company logo, I found it connected with the triac gate, when I checked it with DMM it does not give any sign of diode behaivour.

Can any body help me in this…. thanks

just short mt1 with gate & onther probe to mt2 at ohmmeter

hai

this method might work keep your digital multimeter as ohmmeter and postive at mt1 & also for gate (ie short mt1 & gate temporarily) & keep black probe to mt2 so it trigers usally the traic as some liitle volt to gate & some resistance shown on meter now slowly lift connection from gate but be care still it should conncet to mt1 now resistance remains same as it triggers althoug u removed gate voltage now(actually meter probe volt is engough) once it has trigger it works usally gate will be 1st pin of the device or may be at 3 pin of device so u can use mt2& gate short or mt1 gate short with black for remain pin ie either mt2 & mt1 respectivly if still u want u welcome to my personnel mail viji2ks@yahoo.com