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Question 1)When a triac blows on a PCB is it always the case to assume that the component that the triac actually controls is at fault?
Question 2) Or do triacs blow of their own accord sometimes?
Question 3) To be certain of locating the external component is it correct to trace its centre pin circuit to its nearest module connector block?
Re: Questions for a PCB (electronic) whiz kid?
Hi Martin: A Triac that’s physically blown apart is usualy due to the component it drives shorting out or drawing prolonged excess current.
Triacs can & do sometimes blow without outside cause but normally with no physical signs.
Unfortunately as with Transistors, Triacs can have different pin configurations. Having said that those in domestic appliances do tend to follow the same pin out, but a good Semiconductor reference book can be very useful especially if trying to find an equivalent.
Triacs can be easily tested out of circuit using an Analogue meter as follows: Identify MT1, MT2 & Gate terminals set the meter to Rx1 on the ohms range. Connect the meter across MT1 / MT2 either way around & this should read completely o/c i.e infinity.
Short the MT2 lead to the Gate lead the ohms reading should now go low.
Remove the short & the low reading should stay the same.
HTH Regards: Andy 8)
Semiconductor reference books & replacement Triacs can be obtained from http://www.cpc.co.ukRe: Questions for a PCB (electronic) whiz kid?
Specialist01269 wrote:A Triac that’s physically blown apart is usualy due to the component it drives shorting out or drawing prolonged excess current.
Could a triac blow if subjected to excessive use, i.e switched on and off rapidly and constantly by an overworked anti-flood safety switch?
Re: Questions for a PCB (electronic) whiz kid?
Hi Martin: Although I have never actually come across that particular situation, I would say yes. I take it that the Triac in question was driving the pump? if so & the pump is continually drawing current then eventually the Triac will overheat & blow, as far as I know they are not rated for continual current and manufacturers being manufacturers usually use the lowest rated (Cheapest) components they can get away with. :rolls:
Andy.Re: Questions for a PCB (electronic) whiz kid?
Specialist01269 wrote:I take it that the Triac in question was driving the pump? if so & the pump
Well no, the triac in question is driving the inlet valve on a Neff dishwasher where the anti-flood device was constantly switching the valve on and off. Like some adolescent schoolboy constantly flicking a lightswitch.
Hence the conundrum of not being entirely sure how a triac would react given these circumstances? 😕
Re: Questions for a PCB (electronic) whiz kid?
Hi Martin: I was talking to a coleague about this earlier, & the answer we both came up with was yes. If the Triac is being constantly switched on/off then it will eventualy die on you no matter what it’s switching.
Andy.
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