Good Morning. This is in addition to another thread but I have a router that uses a BTA24 TRIAC and U211B Phase Control to vary the speed of a router motor. I have checked most of the components on the board and the only thing I found was a blown 1.5uF capacitor (SMD). I have replaced the capacitor and no change. I am not real familiar with the two components I mentioned but perhaps someone could tell me how this circuit works in laymans terms.

http://pdf1.alldatasheet.com/datasheet-pdf/view/26114/TEMIC/U211B.html

 

Schematic? There are several in the data sheet. Does your schematic resemble one of them? Which capacitor in the schematic corresponds to the one you replaced?

Do you know the triac is still good? In my limited experience, "it's always the triac".

 

Do you know the triac is still good? In my limited experience, "it's always the triac".

+1,
This is just about the only device that consumes any appreciable power.
There is usually no more than 5 devices so it is very easy to reverse-engineer.
Max.

 

I'm kind of suspecting the TRIAC to be the culprit but not sure how to test it. I had ordered in a pair to replace it with and haven't done that yet. Any ideas how I can test them. The circuit is very similar to the one on page 2. I have a hand drawn version at home I can post if you want to see it later.

 

If you want to test the triac, use a low voltage secondary of a 6v, 12v transformer and place the triac in series with a suitable lamp and connect the trigger of the triac to the transformer/triac lead using a 150 ohm resistor.
It should turn on and off.
Max.