In the early 80s I worked at a company where we used thousands of TRIACs per week on many products.
wow must be beautiful years
If I recall correctly every TRIAC failure that I saw was always a shorted device.
Yes, I guess pretty much most semiconductor devices are shortened when they fail.
How are you measuring the gate's 9 volts? From gate to what point? It should be to MT1.
I'm measuring it from the gate to the circuit DC ground.
Please, if you could check post #4, I included an image with squares of the important parts.
If you check the traic signal bath, it's coming from a transistor. But the 9V actually coming from the DC power supply which regulates 5 and 9V for the control circuit, it has one little pic microcontroller.
But you know, maybe there's something wrong with the microcontroller. I receives a signal from the switch and activate the transistor which in turn activate the triac. But there's always 9V on the triac's gate!
Be aware though, since a TRIAC is a latching device, the gate drive may be a narrow pulse with a phase shift, which you cannot really measure with a DMM.
So if it's a high frequency pulse, then it should be coming from the mcu, so if there's just plain 9V without pulsating, then the chip is broken, because I think the mcu could just drive the low pulse of the 9V, so if the mcu is broken then there's a 9V on the triac's gate ... that's my guess.
Lastly, TRACs are not voltage driven but current driven. You should really measure the voltage drop across the series resistor. But again, if it is a pulse, you won't see it with a DMM.
Ahaa, so do you mean that I can't measure the actual voltage on the gate? But if I'm getting 9V from the gate to the common ground of the circuit, then what does that mean?
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I'm actually thinking to disconnect the mains rails and connect them directly to the motor, is that safe?