Here's my update and simple fix for the problem. Initially I was just shown
the speed control board just to see if I would be willing to have a go at
it. This is why I was looking for access to a schematic out there. Anyway, I
said sure so the person brought me the whole saw. I popped open the switch
panel on the saw and found a wiring problem so it turned out to not be the
control board after all. It seems the owner was cutting something and the
saw popped its lock. The owner reset it and it popped again. The owner
thought it might be something happening behind the switch panel so he popped
it open. In the process he accidentally switched one of the wires going to
the power switch with one of the wires going to the light bulb switch. At
this point the saw wouldn't work at all when he switched it on. Thank God he
had only switched the two wires he did. If he had switched any other wires
he would have had a pretty loud bang when he tried to power the saw on since
he would have created a dead short in the AC line and it probably would have
knocked him ass over teakettle. Anyway, I swapped the wires back to where
they should be and everything was good again in a matter of a couple of
minutes.
I know some people take offence when they ask a question and have other
people tell them to keep their noses out of it or they might get hurt. Most
times I don't think the ones saying to stay out if not experienced are being
cruel or anything like that. They are just trying to help prevent someone
from getting seriously injured. So, if you are reading this and you don't
consider yourself to be experienced in repairs then please take the time to
seek good help before tackling what may appear to be a simple task yourself.
The fingers you save just might be your own.

Cheers,
Lawrence