How to Bypass a Thermo Switch on a Hitachi Table Saw

Hitachi manufactures a variety of power tools for woodworking, including portable table saws. Like other table saw models, the Hitachi is equipped with a thermo switch that monitors the motor temperature while cutting materials. If the heat exceeds the rated level, the thermo switch cuts off and shuts down the saw. However, if the table saw cuts on and off repeatedly, the thermo switch may be going bad or is already defective. Running a temporary bypass lets you determine if the switch is the problem.

Things You'll Need

  • Screwdriver set
  • Pliers
  • Electrical tape
  • Scissor


    • 1

      Unplug the Hitachi power cord and turn the On/Off switch to the off position.

    • 2

      Take off the panel on the bottom of the table saw adjacent to the motor housing, using a screwdriver. Follow the route of the wires from the motor to the round part below the saw. This round component is the thermo switch.

    • 3

      Loosen the screws on the terminals holding the four wires on the thermo switch. Pull the wires off the screw terminals.

    • 4

      Twist the two black wires together to form a splice. Twist the white wires together in the same manner. The circuit is now set up to bypass the thermo switch and provide continuous power to the motor.

    • 5

      Plug in the power cord for the Hitachi and press the power button to the "On" position.

    • 6

      Start and operate the saw normally. If the motor drives the saw blade though it would not work previously, the thermo switch is defective.

Tips & Warnings

  • Replace the switch before using the table saw, as running in bypass mode can overheat and burn out the motor when cutting hard woods.
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