TRIACS

I don't think its normal for a triac to fail if right triac is used in right circuits.no manufacturer will survive if he made it for normally to fail. probably triac used is under rated or something is wrong with circuit.

Check the triac rating for gate voltage, gate current, terminal voltage rating and terminal current and see if everything is with in specification with your circuit, also you can put a surge suppressor in your circuit.

I think you have hit the nail on the head..!! you are right, the input voltage is rated at 100v - 240v. There are a pair of switching transistors, together with a couple of Dual schottkys at the (I presume) output stage, all of which seem to have survived. Anyway I,ll put it all back together, minus the TRIAC, and we'll see how we go.! Thanks mate, Norm.

If you're to connect back to mains use some current limiting like a 100W filament bulb in series if you can find it nowdays or something similar. And be VERY carefull. 300VDC is VERY dangerous voltage S.M.

I take it that the 100 watt globe, is simply a precaution to take during the first re-connect to limit fault currents should something else decide to explode. Great idea...!!! thanks again, Norm.

May I also add that the 100 watt bulb should be wired / connected in series with your circuit. If it glows bright , you still have a short somewhere that is drawing much current. If it is dimly lit then it safe to assume that there is no other bad component left in your circuit!

What are the letters on the device?- using these & a semi equiv book- or even googling them- will identify device. If triac- without dedicated triac tester- using multimeter- G-mt1=low b/w- mti-mt2=inf b/w-mt2-g= inf b/w- can be leaky or defective also- any doubts simply replace device with suitable equiv or slightly higher rated.

Hi guys, All is well..! The triac was faulty, but acting on advice of this column, I left it out, fired it up and all went well... Brilliant....! Thanks guys, one and all for your advice & support, I've said it before, and I'll say it again, one is only as strong as one's circle of friends. Thanks again, Norm.