These will be brush/commutator motors, so nothing special to start them. As stated before, I believe there will be some sort of cheap latch function (solid state or mechanical) built into the trigger assembly that is sticking on. Power from the trigger would latch it on as long as the brake switch was closed and either switch opening should unlatch it. If the trigger switch assembly looks to be a molded unit that can't be taken apart, there is probably a solid state function buried inside. Parts diag. will probably show only the trigger switch and the brake switch. The manufacturer will have found the cheapest way to make the saw safe.
What you say is EXACTLY what I thought.
Here is what happened in feal time.
When the trigger was released the saw kept running. Then to shut it off I pushed the hand brake FORWARD. The chain stopped immediately.
The motor began loud humming and began overheating.
Now it would be highly unlikely both switches failed at the same time.
So after the MAIN switch was opened the power to saw off the saw was left to cool.
The hand lever PULLED TOWARD the saw to release the chain.
Main extension cord switch was off. Saw setting on the ground. Both switches cycled. Trigger switch toggled several times. Main extension cord switch flipped on Saw chain starts running. Power cord flipped off saw stops. Trigger switch toggled hand brake switch FORWARD. Power cord switch flipped on. Saw should have no applied power with safety brake on but motor grows and tries to run. The chain is locked the motor is struggling to run getting hot. At this point are both switches stuck?
After 4/5 times of this and much toggling of both of the switches finally when extension cord switch is on the saw stopped running. Everytime the power switch was flipped on powering up the supply the saw motor powered up. Finally after a lot of toggling and power cord on and off the saw works correctly.
In my mind IF the trigger switch is stuck closed. WHY did the safety switch not stop power to the motor???
Thankfully My extension cord has a cut off switch which I installed years ago as a safety measure. Infact there's a switch on both ends of the power cord because when my grandkids are using the cord I wanted to have the ability to shut power off quickly. If something goes wrong the power cord can be turned off immediately. Thankfully that quick response saved the saw motor.
When I toggled the trigger it clicks as if it good.
Now saw working properly. This saw has done this a few times
Like you say. It seems like the Trigger switch is sticking BUT why did the safety switch not stop power from the motor?????
. Testing shows both switches working well now.
With safety switch open Hand brake FORWARD all the way clicking in place. The trigger can't make motor run which is exactly what should happen
This problem should be on a test!!!!.
There is ONE likely hood.
What IF (I play this game often), what IF, for some reason. The safety hand brake switch LOCKED the motor BUT after doing that it DIDN'T actually actuate the power off switch like it should. Could it be the hand switch failed to cut power but locked brake anyway ?
If so WHY?
Was it not fully engaged?
Is it possible to be engaged to the point of locking the chain but not engaged enough to open the safety switch.
Could it be BOTH SWITCHES have gotten sawdust in them and both failed at the same time?
Like I said. This should be a final exam question. Thanks