Electronics > Repair

BT131 09H Triacs logic level


Hi All

Thanks for letting me join your forum , let me start by saying that I am not into Electronics per se , my hobbie is really repairing Laptops , with having to solder up some very ,very tiny components ( I use a microscope for that small ic parts ) , just leting you know I have a bit of knowledge of circuit boards .

well back to the point in question , my daughter has one of those fancy lights that is touch sensitive for switching on and to go from low to high with tapping the lamp holder 1,2,3 times something like that anyway , well it stopped doing what it is supposed to do , so me being me not to bin it, opened it up ( see pic uploaded ).

pic shows blown Triac , now I have ordered a "BT131-600,412 TRIAC 600V-1AMP SOT54" will this be a replacement for my "BT131 09H Triacs logic level " and off course any other info you can give me .



The specs are nearly identical, but why has the triac blown ?

I would guess the lamp in the unit is either a CFL lamp, or the original lamp was a 150W one, and the triac overheated from too much current. The CFL lamp will kill it from the switching current spikes as the triac tries to drive it and the 150W lamp is just too big. As the board is scorched from heat around the little triac i would guess it was a too high power lamp.

For instant kill it would be an incandescent lamp that failed at switch on and was short circuit during it's failing.


Thanks for your replies , She did say that the bulb made a noise when it blow , but she has thrown that bulb away , so I am not sure what size bulb to put in , I would of thought 150W would be way to high , it is only a bedside table lamp I would of thought a 60W incandescent would be Max ! , or a 20W Halogen ! .



So a blowing bulb did it in. Buy a few spare ones then, so that you can replace it next time when it blows. Otherwise add a NTC thermistor in series with the mains input, to keep the spike down on turn on, which both helps protect the triac and prolongs lamp life considerably. 4R7 or 10R one from an old PC power supply ( black or green 2 legged unit in the mains feed ) will work here.


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