I have a Hakko FX-888D soldering station which stopped heating the iron. I found out that the triac (which is a BTA06-600b) went bad so I went ahead and replaced it with a BTA12-600bw. It didnt work. The triac was off all the time even though it was getting its triggering pulses (I know because I saw it in the oscilloscope and compared it with another working soldering station of the same model and brand).
The replacement triac was ok, it was knew and I also tested it outside the circuit.
I know the problem was just that because later I soldered another triac of the same the station came with and it worked.
If you check the datasheets of the two triacs you can see they are really close in specs, so, why didnt it work?