How to Replace the Field on a DeWALT Polisher
Finish Nailer Repair - Replacing the Driver Guide (Ridgid Part # 79004001022)
The field is the outer portion of your polisher's motor. It works with the armature to create an electromagnetic field, which causes the armature to spin. Most problems with the field are caused by overloading the tool. When the tool is overloaded, the field windings can be burnt. Common symptoms of a bad field are loss of power and excessive sparks from the armature. There will often be smoke coming from the motor, or a burning smell. A bad field can quickly cause the armature to also fail, so you'll want to inspect it closely as well.
Let's get started.
REMOVING THE FIELD
1. Remove the motor brushes.
a. Use a screwdriver to remove the two brush caps.
b. Remove the motor brushes from the brush holders.
2. Remove the armature.
a. Remove the four screws securing the gear case to the field case.
b. Remove the gear case.
c. Remove the armature assembly from the field case.
3. Remove half of the handle.
a. Remove the screws securing the top half of the handle to the lower half.
b. Lift the top half of the handle away from the lower half.
4. Disconnect the field.
a. Note the location of the field wires (for reassembly).
b. Use long-nosed pliers to disconnect the four wires from the field.
c. Remove the speed sensor from the back of the field case.
d. Disconnect the wire lead from the brush holder.
5. Remove the field.
a. Remove the plastic fan baffle plate from the field case.
b. Remove the two screws securing the field to the field case.
c. Pull the field wires free from the clips securing them to the field case.
d. Invert and tap the field case against your work surface to loosen the field assembly.
e. Remove the field from the field case.
INSTALLING THE NEW FIELD
6. Install the field.
a. Place the new field assembly on your work surface with the field wires facing up.
b. Orient the new field assembly so that the yellow wires align with the left side of the grinder (if it were assembled).
c. Begin installing the field case onto the new field (with the left side of the case aligning with the yellow wires).
d. Thread the field wires up and out of (the back of) the field case (use long-nosed pliers as necessary).
e. Slide the new field assembly fully into the field case.
f. Secure the field to the field case with the two screws.
g. Reinstall the plastic fan baffle plate.
REASSEMBLING THE UNIT
7. Reinstall the field case assembly.
a. Secure the field wires in the plastic clips on the field case. (Use a small screwdriver as necessary).
b. Connect the single black wire lead to the brush holder.
c. Connect the second black wire to the brush holder on the opposite side of the field case.
d. Note that there are two sets of wire connectors on each side of the field case. Each set contains a large and a small terminal. Connect the yellow wires to the SMALLER terminals on each side of the field case.
e. Align the field case with the lower handle assembly.
f. Reinstall the speed sensor onto the back of the field case.
g. Install the field case onto the lower half of the handle.
h. Connect the red and white wires to the larger terminals on the field case.
i. Tuck the field wires into the channels on the lower handle housing.
8. Reinstall the top of the handle.
a. Tuck any exposed wires into the lower handle.
b. Install the top half of the handle.
c. Secure the top half of the handle with the screws.
9. Reinstall the armature.
a. Partially install the armature assembly into the field case.
b. Align the metal tabs on the armature plate with the slots on the field case.
c. Press the armature assembly firmly into the field case.
10. Reinstall the gear case.
a. Install the gear case onto the motor housing.
b. Secure the gear case with the four screws.
11. Reinstall the motor brushes.
a. Install the motor brushes into the brush holders.
b. Secure the motor brushes with the brush caps.