Scotsman NW308 Service Manual page 28

components output, and two buttons for
MODE and clean, and one DIP Switch for PC
board setup.
3. Compressor Contactor
Located in the control box, the compressor
contactor functions to carry the compressor
line current. The contactor is wired to receive
power from the P.C. Board.
4. Ice Thickness Sensor
Located in the front upper right side off the
evaporator, the sensor is made with two metal
reeds in which passes power at low voltage.
The two metal reeds, which are individually
insulated, are set through a setting screw, to
maintain a minimum clearance from the
evaporator (3~5 mm). Once ice is formed into
each mold and is thick enough to fill-up that
minimum clearance existing between the two
sensor reeds and the evaporator, the water
that cascades over the ice has gradually
approached to make contact between the two
sensor reeds.
It is enough that this contact remains there for
about 10 seconds that the P.C. Board receives
the signals to put the ice machine on defrost.
5. Magnetic Switch
Located in the front of the evaporator plastic
curtain, this switch sends a pulse to the P.C.
Board which switches the machine back in the
freezing cycle.
6.Hot Gas Solenoid Valve
The Hot Gas Solenoid Valve functions only
during the Harvest Cycle, to divert the hot
discharge gas
bypassing the Condenser and thermostatic
expansion valve, for direct flow to the
Evaporator Plate Assembly to release ice
cubes from the ice cube molds.
The Harvest Solenoid Valve is comprised of
two parts, the Body & Plunger and the Coil
assembles.
Installed in the
Compressor, the energized solenoid coil lifts
the valve stem within the valve body to cause
the hot discharge gas to be diverted when the
ice Thickness sensor has signaled to the P.C.
Board to start the Harvest Cycle.
7. Condenser temperature sensor
from the Compressor,
discharge line
The condenser temperature sensor probe
(located in contact with the condenser tube
coil) detects
variations and signals them by supplying
current, at low voltage, to the P.C. BOARD.
In the air cooled versions, in relation to the
different current received, the micro processor
of the P.C. BOARD supplies, through a TRIAC,
the power at high voltage to the fan motor so
to cool the condenser and to reduce its
temperature.
In case the condenser temperature rises and
reaches 70℃ (158F) the current arriving to the
micro
immediate stop of the machine operation with
the blinking of the Red LED, and first two time
machine will automatic restart, the machine
will total stop when high temperature occurs
the third time, And press MODE button can go
to start up cycle.
8. High Pressure Control
The high Pressure Control, a safety control, is
factory set to cut-out, at 33bar and cut-in at 22
bar. The control, functions as a precautionary
device to shut OFF electrical power to
Icemaker, should a loss of water occur to the
water cooled Condenser or a burnt out of the
fan motor on air cooled versions. The high
Pressure Control is manual reset with reset
button located on the rear side of the machine
and a monitoring light on the Front Console
Panel.
9. Water Regulating Valve
(Water Cooled Models)
The Water
maintain
pressure,
incoming water flow through the Condenser,
on water-cooled models. The valve operates
through the refrigerant system high side
pressure. Rotating the adjusting screw located
on top of the valve, can INCREASE or
DECREASE the water flow through the water-
of the
cooled
DECREASE or INREASE the Compressor
operating head pressure.
10. Water Distribution System
The Water Distribution System functions to
even supply water to all cells of the evaporator
plate. The water pump pumps water from the
27
the condenser
processor is such
Regulating
a constant Compressor
by regulating
Condenser, which
temperature
to cause an
Valve functions
head
the amount of
in turn, will