Single Microswitch Gear Motor; Temperature Sensor (Adjustment) - Philips 4000 Service Manual

PHILIPS 4000

3.1. Single microswitch gear motor

When the machine is switched on, the gear motor repositions itself as follows:
- It acts on microswitch 1
- The gear motor changes its rotation direction and moves upwards again by approx. 1-2 mm.
- The boiler begins to heat the water for approx. 45 sec, in order to reach the optimal temperature (established
by the software).
The gear motor is powered by a direct current motor that engages with the smaller double toothed wheel us-
ing a worm screw. The unit is mounted on the axle of the large gear wheel and when a coffee is requested, it
moves from the standby position to the dispensing position, and then back to the standby position again.
The microswitch indicates to the gear motor when the brew group is in the work position or home position.
- Standby position: 1
- Dispensing position: 2

3.2. Temperature sensor (adjustment)

An NTC is used as a temperature sensor; in the event of overheating this reduces boiler element power
consumption. The electronic system detects the current boiler temperature from the drop in voltage of
the sensor and adjusts it accordingly. Heating element values and corresponding temperatures: see table.
Switching on
Temp. (°C) R nom (kΩ)
20 61.465
50 17.599
75
80
85
90
100
125
150
1
ΔR (+/- %)
8.6
5.9
7.214 4.1
6.121 3.7
5.213 3.4
4.459 3.1
3.3 2.5
1.653 3.9
0.893 5.1
03 OPERATING LOGIC
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