AIRLESSCO LP500 - Manual (Page 18)

Troubleshooting
18 3A1185H
Motor Remove the motor brush covers and turn the
machine ON. Set the potentiometer (POT) at
maximum pressure and check for DC voltage
across both brush terminals. It should read
greater than 80 volts DC.
If you have DC voltage, turn the machine off
and unplug it from the wall. Check to make
sure the brushes are making good contact
with the armature. Replace the brushes if they
are less than 1/2” long. If the brushes are
good, replace the motor.
If you do not have DC voltage, see Sensor.
Sensor Plug another sensor board into the board and
perform the zero calibration procedure. If the
machine starts to run, the sensor is bad. If
there is no replacement sensor available, use
a multi-meter to test the resistance across the
red and black wires of the sensor (be sure to
test the plug). You should read 1.5 - 3.5k
ohms. A faulty sensor usually reads no conti-
nuity (open).
If the sensor passes all the tests, see Pres-
sure Control Knob (Potentiometer).
Pressure Control Knob (Poten-
tiometer) Plug another potentiometer (POT) into the
control board. If the machine starts, the old
POT is bad.
When a replacement POT is not available,
remove the POT lead (with the machine
turned off) from the control board and test the
resistance between the red and black wires
(be sure to test at the plug). The resistance
should read between 8-12k ohms. If it is out-
side of this range replace the POT.
If there is DC voltage at the motor brushes
and the sensor and pressure control knob are
functioning, replace the pressure control
assembly.
Problem Cause Solution