44Service Manual – SC900 30 - Solution System
Detergent Models
Machines that have on-board detergent
mixing (EcoFlex Models) have a solution
control circuit board, detergent pump,
and detergent bottle. From an enabling
standpoint, the detergent module (circuit
board) has the same prerequisite control
that a non-detergent solution solenoid has.
The machine must be in motion, and the
scrub brushes be active.
However, instead of battery negative
passing straight to the solution solenoid,
it passes into the detergent control board.
This signal serves as an “Enable” function
for the detergent and solution outputs.
Within the detergent module control board
is a micro controller that generates PWM
outputs for both the detergent pump and
the solution solenoid. This is a battery-
negative PWM, and applies negative
voltage to the coils.
The two duty cycles of the PWM outputs
are controlled by onboard potentiometers.
The Burst of Power switch will
temporarily increase both detergent and
solution ow rates for 60 seconds.
Detergent Pump
The detergent pump is a solenoid-driven
diaphragm with one-way check valves. As
the solenoid oscillates in and out, it drives
a exible diaphragm that draws uid in
during the retraction stroke, and drives
uid out during the compression stroke. The
check valves allow uid to enter only though
the inlet port, and exit only through the
outlet port.
Unlike an AC solenoid that moves its
plunger the same direction regardless of the
electrical polarity, a DC solenoid changes
its direction of travel depending on the
electrical polarity of the coil. This is an
important distinction because if the pump is
connected with the wrong polarity, it will not pump liquid.
The solenoid plunger is actively driven in only one direction (intake), but passively returned via the return
spring (exhaust). If the wiring polarity is reversed, the solenoid plunger will be driven in the same direction
that the return spring has already pushed the plunger. So the plunger will never move.
BLK
BLK
BLK
PNK/WHTVIO
PNK/BLU
VIO/WHT
PNK/BLU
VIO/RED
VIO/GRN
VIO
PNK
VIO
PNK
S1
SW, SPST KEY
S4
SW, BRUSH
P3 DETERGENT MODULE
B+
1
B-
5
SOL IN
2
SOL- OUT
3
DET- OUT
4
BRAKE+
6
RELAY, LVC
1
2
3
4
5
6
CURTIS 1228
KSI
5
BRAKE-
6
BRAKE+
14
D2
K1 RELAY, LVC
BATTERY GAUGE WITH HOURMETER
FET DRAIN
3
B-
4
L1
COIL, SOLENOID
1 2
L2
PUMP, DETERGENT
1
2
D1
36 VDC
+ -
K2
COIL, BRUSH
K1
Outlet
Inlet
Pos
Neg
Diaphragm
Solenoid
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