Bosch TCA640 Series Repair Instruction page 35

4.4.3 Cam on the gear unit
The position of the brewing unit is detected with two micro switches
S1 and S2. These two switches are able to define three positions.
When the appliance is switched on, the switch status of the micro
switches is checked and transmitted to the control module. The
brewing unit is moved to the basic position (= initialising).
Home position
S1 ON
S2 OFF
58300000120060_ARA_en_c.doc – 18.09.09
Brewing position
The brewing unit
is in the grinding
position and can
be filled.
Switch S1 is
activated by
switch cam (A).
Switch S2
remains open.
S1 OFF
S2 ON
Drainage position
The transmission
turns clockwise
until switch S2 is
closed by switch
cam (A) and
switch S1 is open.
The brewing unit
is in the brew
position. The
transmission
motor stops.
Water can be
supplied and
coffee can be
brewed.
S1 ON
S2 ON
Once the brewing
process is complete,
the system is
drained.
For this, the motor
turns the cam disc
back by about 8°, so
that the drainage
valve is opened
again and the
remaining water can
run into the drip tray.
Switches S1 and S2
are closed.
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