16
MT GL/GLS/UL
6 Compressor is on.
figure 10
As soon as liquid begins turning into slush, its viscosity
increases: the more the slush is progressing the more it
increases in viscosity.
This results in (gradually) increasing resistance to mixers, and
then to mixer motor C, rotation.
For the combined action of increased resistance and motor
torque C, the mixer motor which is pivoting on its shaft like a
pendulum, is driven to swing upward.
The spring B is set against such an angular displacement: the
more the spring is loaded through the screw AF the more it
opposes mixer motor upward displacement.
Therefore the mixer motor will be able to shift only when the
viscosity of the mix is so much increased as to generate on the
mixer motor itself a torque exceeding the spring B action.
Granita final viscosity is then depending upon screw A
adjustment: in fact as soon as mixer motor C shifts, microswitch
D gets off and solenoid valve E is deenergized thus stopping
refrigeration in the bowl.
Mixers continue to rotate and when the Granita gradually loses
viscosity (being refrigeration off) the mixer motor goes back so
as to reactivate microswitch D, reenergize solenoid valve and
restart refrigeration in the bowl.
To change Granita final viscosity is then enough to turn the
adjustment screw A:
7 clockwise to obtain thicker product (the indicator will go
downward in the opening of the rear cover F).
8 counterclockwise to obtain thinner product (the indicator will
go upward in the opening of the rear cover F).
12. 2 MIX TEMPERATURE CONTROL (DRINK
MODE)
When any of Mixer/Refrigeration switches is in I position, the
relevant section of the unit operates as an independent
beverage cooler.
To this end, each section (bowl) is equipped with a thermostat
that controls cool down and shuts off refrigeration when the
product reaches the preset temperature, by deenergizing the
relevant solenoid valve.
NOTE: The thermostat acts on the bowl refrigeration control
system only when the bowl is set to Drink Mode (position I of the
mixer and refrigeration switch).
On the contrary when the bowl is set to Granita Mode (position II
of the switch) the thermostat is always automatically
disconnected and therefore it does not influence the Granita
viscosity which is controlled by the screw A.
The thermostat operation temperature may be adjusted by
rotating the knob located inside each switch box.
To decrease beverage temperature, turn the knob clockwise
and counterclockwise to raise it.
When knob is set at the coldest position, the shut off
temperature is around 2-3°C.
When knob is set at the warmest position, the shut off
temperature is around 11-12°C.
For all the positions the differential is around 3°C.
Thermostat probe is located in the bottom zone of the
evaporator holder, inside a stainless steel housing.
In case of replacement, it must be removed from the rear side of
the unit, once taken away the rear cover.
12. 3 PRINTED WIRING BOARD (PWB)
CONTROL - MACHINES MANUFACTURED
UNTIL DECEMBER 2001
The device is designed to delay:
1 The opening (energizing) of solenoid valves (10 - 15
seconds from the moment that relevant microswitches are
activated).
2 The starting of compressor (approx. 3 minutes from the
moment that at least one of the solenoid valves is opened).
3 On “GLS” models the electronic delay device is also aimed
to stop the gear motor and shut the corresponding solenoid
valve when the top cover is not properly located on the bowl.
When a multiple bowl unit is running and an obstacle takes
place in whichever of the bowls (e.g. some ice formed around
freezing cylinder), the relevant mixers keep on stumbling
against it and the mixer motor keeps on swinging like a
pendulum and switching off and on the relevant solenoid valve.
This would allow an intermittent refrigerant flow into the jammed
bowl and, consequently, the obstacle would not be eliminated
but magnified.
The delayed opening of the solenoid valve avoids such
undesired refrigerant flows until the ice is melted.
The compressor shuts off as soon as all the solenoid valves are
deenergized and starts back again as soon as at least one of
them gets reenergized.
Sequence and timing of solenoid valves re-opening are
unpredictable and could take place any time, even before high
pressure and low pressure sections of the circuit are balanced,
what would overload the compressor.
In order to prevent such an event, the compressor re-starting is
delayed and allowed only after 3 minutes from the moment that
whichever solenoid valve is energized.
12. 4 PRINTED WIRING BOARD (PWB)
CONTROL - MACHINES MANUFACTURED
AFTER JANUARY 2002
On a multiple bowl unit operated in Granita mode the device is
designed to delay:
1.The starting of compressor of approx 60 seconds when the
unit is switched on.
2.On "GLS" models it is also aimed to stop the gear motor and
shut the corresponding solenoid valve when the top cover is not
properly positioned on the bowl.
The solenoid valves are directly operated by the microswitches
and the compressor runs all the time, also when all the solenoid
valves are closed. In this case the evaporators are emptied of all
the refrigerant gas which is kept liquid inside the condenser until
when one solenoid valve re-opens again.
On a multiple bowl unit operated in Soft Drink mode the device
is designed to delay:
1.The starting of compressor of approx 60 seconds when the
unit is switched on.
2.The starting of the compressor of approx 60 seconds from the
moment that at least one of the solenoid valves is opened by the
corresponding thermostat.
3.On "GLS" models it is also aimed to stop the gear motor and
shut the corresponding solenoid valve when the top cover is not
properly positioned on the bowl.
The solenoid valves are directly operated by the thermostats of
each bowl and the compressor shuts off as soon as all the
solenoid valves are de-energized and starts back again as soon
as at least one of them gets re-energized. Sequence and timing
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