Electrolux ADW750EA, Service Manual

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Page 7
CONSTRUCTION & OPERATION
Not all of the water is blocked however. The opening is
constructed to allow a small amount of water to bypass
the ball and enter the tube, and fills the tube at a rate of
approximately four inches a second. At the same time,
the outlet to the lower spray arm is open, so the lower
spray arm operates. When the pump stops, the pressure
is removed from the ball and the water flows down the
tube, forcing the ball up the ramp and against the outlet
to the lower spray arm. If the pump remains off for more
than 3 seconds, all the water in the tube escapes and
the ball returns to the bottom of the ramp. But, if the
pump is started in less than .6 seconds, the water from
the upper arm delivery tube is still forcing the ball up the
ramp against the outlet to the lower spray arm. The
force of the water from the pump continues to hold the
ball against the outlet to the lower spray arm which
leaves the outlet to the upper arm delivery tube open.
When the ball is in this position only the upper spray arm
operates. This momentary stopping of the pump is
controlled by the control board.
Another unique feature of the water distribution system
is the two cavities of the sump. One cavity provides
filtered water to the pump for recirculation through the
spray arms. The other, called a quiet water cavity,
allows soil to collect in the area of the macerator blade,
where it is held until the drain pump removes it.
WATER DISTRIBUTION COMPONENTS
Wash Pump
The recirculation (wash) pump has three (3) functional
parts, a 1/12
th
HP drive motor, impeller, and macerator
blade. The pump circulates water at the rate of 12
gallons per minute. This pump is used only during the
wash cycle, a separate pump is used during the drain
cycle. The wash pump is to be replaced as a complete
assembly.
WATER DISTRIBUTION SYSTEM
The water distribution system consists of an upper and
lower spray arm, upper (spray) arm delivery tube, filter,
soil director, pump, sump, and check ball. The system
is designed to operate only one spray arm at a time.
During the first wash and first and second rinses, only
the lower spray arm operates. In the second wash, third
and fourth rinses the spray arms alternate about every
90 seconds.
This alternating of the spray arms is achieved with a
check ball located on a ramp between two outlets of the
pump. There is an outlet to the bottom spray arm and an
outlet to the upper arm delivery tube. In the normal
position the ball is at the bottom of the ramp, in front of
the opening to the upper arm delivery tube.
When the pump starts, the force of the water pushes the
ball to block the opening to the upper arm delivery tube.