Wizard
Control Box
The control box is the most complicated piece in the machine. It
can be divided into the following systems:
* Power supply - Turns high AC voltage into 18 volts DC (to
power the board relays), and 5 volts DC (to power the
microprocessor and logic circuits.)
* Auto-fill sensing circuit - Sends power to the auto-fill probe
looking for ground.
* Input - Ribbon cables carry information between the menu
button pads and control box.
* High voltage output - This provides power to the coils and pump
motor when the machine is called upon to brew
espresso.
The power supply in the control box consists of:
* A 6.3 amp fuse, which protects the brain from a direct short to
ground.
* A 40mA fuse, on 4 groups only, which protects the rest of the
components in the event that something has shorted in
the DC system.
(i.e.: a Flowmeter)
* The transformer is the cube on the board. Its purpose is to
reduce the high AC voltage to 18v AC. The 18v AC then
passes through a bridge rectifier, which is a series of
diodes, that convert the AC signal into DC, which then
goes through a 1000mfd capacitor, which filters out any
remaining AC signal.
Field
Impellor
O-Ring
Body
*The best test point to verify DC voltage is on connector #2, pins 5 and 6, or from the red flow
meter wire to chassis ground.
There are three different versions of control boxes that have been used with the LaMarzocco. Until
approximately 1990 there was a Non-Mask Control Box. It has 8 pin connectors and colored ribbon
cables. Until approximately 1995 the Mask Control Box was in use. It has 10 pin connectors and
grey ribbon cables.
Flowmeter
There are three electrical connections on the top of the flowmeter:
* The “+” corresponds to the DC power supply and should always
read 16-22 volts.
* The “-” should go directly to a ring terminal attached to the hous
ing of the flowmeter. This is the ground wire and should
always read 0 volts.
* The “0” is the signal output to the control box. The signal from
this terminal will switch rapidly from 18 volts to 0 volts.
* To test the flowmeter disconnect the red and white wires and
measure ohms to verify that approximtely 2.2K ohms is
present between the “+” and “0” terminals. A reading of 0
indicates a problem requiring replacement of the sensor.
* The acceptable range is 1.8--2.4K ohms.
Non-Mask & Mask
