Graco ULTRA 500 Instructions-Parts List Manual page 17

For checking armature, motor winding and brush electri-
cal continuity.
Setup
Relieve pressure. Remove the drive housing. See page
24.
Remove the motor shield (1), the fan cover (F) and the
inspection covers (J). See Fig. 9.
Remove the pressure control/cover(301). Disconnect
the – and + leads from the motor to the pressure control/
cover terminals M–, and M+. See Fig. 10.
Armature Short Circuit Test
Relieve pressure. Quickly turn the motor fan by hand. If
there are no shorts, the motor will coast two or three revo-
lutions before coming to a complete stop. If the motor
does not spin freely, the armature is shorted and the mo-
tor must be replaced. See page 26.
1
Fig. 9
Fig. 10
F
J
301
Armature, Brushes, and Motor Wiring Open
Circuit Test (Continuity)
Relieve pressure. Connect the two black motor leads to-
gether with a test lead. T urn the motor fan by hand at
about two revolutions per second.
If there is uneven or no turning resistance, check the fol-
lowing: broken brush springs, brush leads, motor leads;
loose brush terminal screws, motor lead terminals; worn
brushes. Repair parts as needed. See page 19.
If there is still uneven or no turning resistance, replace the
motor. See page 26.
M–
–
M+
+