Power tool coil measurement

Measuring the coil or windings in a power tool is an essential aspect of diagnosing and troubleshooting electrical issues within the tool. The coil, also known as the armature or stator, is a critical component of electric motors in power tools. It's responsible for generating the rotational motion necessary for the tool's operation. Here are steps to measure the coil in a power tool:

Important Safety Note: Before attempting any measurements or repairs on a power tool, make sure it is unplugged or the battery is removed to prevent electrical shock.

1. Disassemble the Power Tool:

   • Carefully disassemble the power tool to access the coil or armature. This may involve removing the tool's housing and other components to expose the electrical components.

2. Locate the Coil:

   • Identify the coil or armature, which is typically a cylindrical or barrel-shaped component with windings of copper wire. It is connected to the tool's commutator and brushes.

3. Visual Inspection:

   • Inspect the coil visually for any signs of damage, such as burnt or melted insulation, broken wires, or discoloration.

4. Resistance Measurement:

   • Use a multimeter set to the resistance (ohms) measurement mode.
   • Carefully touch the multimeter probes to the leads or terminals of the coil. Ensure that the probes make good contact with the copper windings.
   • Measure the resistance of the coil. The resistance value will vary depending on the power tool's design, motor type, and specifications. It is usually within a certain range specified by the manufacturer.
   • Compare the measured resistance with the manufacturer's specifications. If the resistance is significantly out of range or shows an open circuit (infinite resistance), it may indicate a problem with the coil.

5. Continuity Test:

   • If the coil resistance measurement indicates an open circuit, you can perform a continuity test to pinpoint the exact location of the break in the coil.
   • Set the multimeter to the continuity or beep mode.
   • Touch one probe to one end of the coil and the other probe to the other end. If there is continuity (a complete circuit), the multimeter will emit a beep or display continuity on the screen.
   • Move the probes along the length of the coil to check for any interruptions in continuity. The absence of a beep or continuity reading indicates a break in the coil.

6. Replacement or Repair:

   • If you find that the coil is damaged or has a significant resistance deviation from the manufacturer's specifications, you may need to replace it. Consult the tool's service manual or contact the manufacturer for guidance on obtaining a replacement coil.
   • In some cases, minor coil repairs may be possible by soldering or reconnecting broken wires, but these should be done with care to maintain the coil's integrity.

7. Reassemble and Test:

   • After making any necessary repairs or replacements, reassemble the power tool, ensuring that all components are securely attached.
   • Test the tool to confirm that it operates correctly and efficiently.

Measuring the coil's resistance and checking for continuity can help identify electrical issues within the power tool and guide you in the repair or replacement process. However, if you are not confident in your ability to diagnose and repair electrical components, it's advisable to seek the assistance of a qualified technician or electrician.