MBM 6020001, Operator'S Safety And Service Manual, Page: 13 / 31

- 8 -
T R O U B L E S H O O T I N G
If your Electric ScreeDemon fails to operate as expected,
the first test will always be to confirm a genuine Milwaukee
battery is fully installed and charged. Removing and
reinstalling the battery will reinitialize the throttle control
board, clearing any faults that were detected during
operation.
Battery Interface
The purpose of the battery interface is to supply 18 volts to
the throttle control board. Typically the battery interface is
known to be in good condition if the LED lights come on
when a battery is inserted. To further trouble shoot the
battery interface, follow the steps below.
Refer to Electrical Assembly, page 20.
1. Remove bottom cover (#5) over the throttle control
board.
2. Identify wires at terminals 3 and 4. These are the
wires which supply power to the board.
3. Insert a known-good battery.
4. Measured voltage between terminals 3 and 4 should
be 18 volts, within 3 volts.
5. If voltage levels are not as described, replace battery
interface.
Electronic Throttle
The purpose of the electronic throttle is to provide a signal
to the throttle control board. The throttle contains a 0-5k
ohm potentiometer to supply this signal. To verify function of
the electronic throttle, complete the following steps.
1. Remove battery from machine.
2. Remove bottom cover from electrical enclosure.
3. Identify, and remove black, brown, and blue wires
from terminals 6,7, and 8, Respectively. To remove
wires, press small button above terminal with small
screwdriver while gently pulling on wires.
4. The measured resistance between the blue and
black wires should be 5k ohms, within 500 ohms.
5. The measured resistance between the black and
brown wires should be under 20 ohms and increase
smoothly to over 4.5k ohms as the throttle is turned.
6. If resistance measured isn’t as described, replace
electronic throttle.
7. When reinserting the wires, be very cautious that all
of the conductors remain contained in the terminal.
18v Motor
The motor utilized by the MBW ScreeDemon is a permanent
magnet, brushed dc motor. It is a permanently sealed and
water tight motor designed to last the life of the machine and
survive wash down with a low pressure hose. To verify that
motor is performing to specifications, follow the steps below.
1. Loosen pinch bolts securing the motor in place and
remove the motor from the exciter assembly. Take
care to not lose the woodruff key.
2. Motor shaft should spin freely without binding. If shaft
does not spin freely, replace motor.
3. Insert a battery and turn throttle. Motor shaft should
spin counter clockwise while viewing the shaft end.
4. If motor does not spin, verify power is being supplied
to it appropriately by the following steps.
5. Remove the bottom over the electronics
compartment.
6. Probe wires in locations 1 and 2. While applying
throttle, voltage should increase from 0 to 18 volts.
7. If proper voltage as described above and motor does
not spin, replace motor.
Throttle Control Circuit Board
The MBW ScreeDemon uses an integrated circuit to control
the power flow between the battery interface and the motor.
This circuit board also controls the LED lights, and provides
over-current protection for the motor. If over-current
protection circuitry is tripped, the LED lights will blink several
times before the board resets. To verify performance of the
throttle control board, follow the steps below.
1. LED lights should illuminate for approximately 30
seconds after a battery is installed, while the motor is
running, and approximately 30 seconds after the
motor stops running. A short dip in the brightness of
lights during these periods might be observed and it
is normal.
2. If over-current conditions persistently occur, confirm
that the eccentric weight freely rotates, no
shockmounts are torn or worn, and remove any
excessive concrete buildup.
3. If ScreeDemon does not operate, and tests for the
battery interface, electronic throttle, and motor do not
show faults, replace throttle circuit board.