If it happens as soon as you turn it on, that sounds like a short somewhere. First thing to check is your cord. If you've damaged insulation and you're shorting out in the cord, this is exactly what you'll see.

If your cord looks fine, it might be worth unplugging the saw, and checking the cord connection to the motor. There's a little box on the side of the motor held on by a single screw. Open it up, look at the connections. As long as there's no copper exposed, you "should" be fine.

If you still haven't found the problem, you probably have an issue in the motor and it would be worth talking to Delta (Service Center link). If you're under warranty, you may be able to get them to just replace your motor.

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