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Motor Diagnostics
18 309674M
Motor Diagnostics
Spin Test
*Note: Motors used in the UltraMax II, Ultimate MX II and ST Max II 490/495/595 model sprayers are brushless. The
following brush information and instructions apply to Ultra, Nova and ST Max 395/495/595 model sprayers only.
Check for electrical continuity in motor armature, windings and brush* as follows:
If Motor Diagnostics reveal a damaged motor or if motor brushes* are shorter than 1/2 in. (12.7 mm) or if the motor
shaft cannot turn, replace the motor, page 29.
Setup
1. Relieve pressure, page 7.
2. Unplug electric cord.
3. Remove drive housing, Drive Housing Replace-
ment, page 17.
4. Remove pressure control cover (50). Disconnect
connector F.
5. Remove four screws (12) and motor shroud (23)
and inspection covers.
Armature Short Circuit Test
Quickly turn motor fan by hand. If not shorted, motor will
coast two or three revolutions before complete stop. If
motor does not spin freely, armature is shorted. Replace
motor, page 29.
Armature, Brushes and Motor Wiring Open Circuit
Test (Continuity)
1. Connect red and black motor leads together with
test lead.
2. Turn motor fan by hand, about two revolutions per
second.
3. If there is an uneven resistance or no resistance,
check for broken brush springs*, brush leads*; loose
brush terminal screws*, worn brushes*, or motor
lead terminals. Repair as needed, page 20.
4. If still uneven, or no resistance, replace motor using
Motor Kit, page 29.
WLD
F
50