Look here brand new, http://www.jwwinco.com/products/section6/gn10/
Hi Subway, sorry taking so long to reply- so it looks like your saw is supposed to be a variable speed but it isn't working. So that transistor is actually a triac. And it looks like the trigger switch unit is actually bad, not the triac (your shorting test seems to confirm that)Correct . The only thing I can see is that it connects to the trigger ....which as far as I can see is not variable , it's just an on or off trigger switch ....and there is also a Hi/Lo switch on the side of the handle .
This is one of those things where it's bad to have OCD ...lol
I could just solder a jumper across it, have it be just "ON or OFF" and call it a day . I have a newer Milwaukee from around 2005 , this is just a spare . but noooo ...the "sickness" won't allow it .
I must fix this thing ....
That part is a 8 amp 400 volt unit. Might be a little marginal as far as reliability. Me, I would bump it up to 10 or 12 amp, 600 volt.If the saw is a 6507, the triac you need is GE SC143D or equivalent.
If the saw is a 6507, the triac you need is GE SC143D or equivalent.