Troubleshooting
18
3A1190H
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 continuity
(open).
If the sensor passes all the tests, see Pressure
Control Knob (Potentiometer).
Pressure Control Knob (Potenti
ometer)
Plug another potentiometer (POT) into the con
trol 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 resis
tance between the red and black wires (be sure
to test at the plug). The resistance should read
between 8-12k ohms. If it is outside of this
range replace the POT.
If there is DC voltage at the motor brushes and
the sensor and pressure control knob are func
tioning, replace the pressure control assembly.
Problem
Cause
Solution
