The thermostat contains an adjustment screw that adjusts the distance the piston must travel
to activate the switch, thus adjusting the temperature.
To increase temperature turn the screw clockwise; to decrease turn counterclockwise.
Each 1/4 turn of the adjustment screw represents approximately 2 degree Celsius temperature
change.
12. HEATING ELEMENT
Each boiler has independently operated heating elements.
The element for the steam boiler receives electrical power from the pressure switch.
The elements for the coffee boiler receive electrical power from the thermostat.
As electrical power is applied to the element it heats the surrounding water in the boiler.
13. CONTROL BOX
The control box is the most complicated component in the machine. It can be divided into the
following systems:
1) Power supply: Converts high voltage AC into 18 volts DC (to power the relays) and 5
volts DC (to power the microprocessor and logic circuits).
2) Autofill system: This circuit monitors the signal from the autofill sensor and determines if
it has established a ground.
3) Input system: These are the ribbon cables that carry information between the menu button
pads and the control box.
4) High voltage output: This provides power to the coils and pump motor when the
machine is called to brew espresso, fill the steam boiler or dispense hot water for brewing
espresso.
5) Power supply: This consists of a transformer, and a40mA fuse. The fuse protects
the components in the event that something has failed or shorted in the DC system.
The transformer is the cube on the board. Its purpose is to reduce the high AC voltage to 18
volts AC. with the help of a series of diodes it is converted to DC voltage.
14. PRESSURE SWITCH
The micro pressure switch controls the steam pressure in the rear boiler by activating a
contactor which supplies power to the heating elements.
When the steam pressure lowers in the boiler (usually 1.1 or 1.2 bar) the contacts close
allowing power to flow from the bottom leads through the top leads and then to the heating
element.
As the steam pressure builds and reaches 1.5 bar the micro switch cuts the power to the
heating elements.
Summary of Contents for Strada
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