Pitch BarPMarks on the Commutator Surface Ground Test (1) Field Terminal. (2) Motor housing. Pitch barPmarks cause low or burnt marks on the commutator surface. 1. Put the digital multimeter Function/Range Switch on the 20M resistance (Ѕ) scale. Field Coil and Terminal Tests 2. Put one test lead to either outer field terminal (1) and the other test lead to the motor housing (2). There must be more than one megohm resistance. Tools Needed 3. If there is a measurement of less than one megohm, it can be caused by wet insulation on the field windings or excessive brush dust in housing. Heat the motor at 88 ° C (190 ° F) until the resistance goes above one megohm.
If the resistance does not go above one megohm, the shell and field assembly must be replaced. Digital Multimeter Or Equivalent 1 Open Circuit Test Open Circuit Test 1. Put the digital multimeter Function/Range Switch on the 200 ohm resistance (Ѕ) scale. 2. Put one test probe to each outer field terminal (S1,S2). 3. The resistance must be less than one ohm. If the resistance is too high, it is an indication of corrosion on the terminals or an open field coil. Power Train Testing And Adjusting 18 EHPS013B Ground Test 2 1 EHPS013B