Turbidity Sensor - Bosch WAT28400 Repair Instructions

Design and function
3.4

Turbidity sensor

3.4.1 Structure
Fig. 4: Components of the turbidity sensor
1 Seal
2 Housing
The turbidity sensor consists of a circuit board (3) on which there is a light barrier.
The board is situated in a transparent housing (2) surrounded by a seal (1). The
housing protrudes into the outer tub.
3.4.2 Function
The turbidity sensor operates according to the principle of a
barrier (Page 12). The water fills the space between the light-emitting diode and
phototransistor of the light barrier. The turbidity of the water determines the signal
strength on the phototransistor.
2017-05-22 / DIS 113_58300000186503_ara_en_c
3 Circuit board with light barrier
light
Copyright by BSH Hausgeräte GmbH
Fig. 5: Function of the turbidity sensor
1 Water
2 Light barrier
The turbidity sensor detects the turbidity of the water in the following programme
steps:
• Prewash
• Rinse
The measured turbidity provides information about the degree of soiling and sud
content in the water.
The measurement result influences the further operation of the wash programme:
• Changing the water for the main wash
• Addition of extra rinse cycles (max. 4 additional rinse cycles possible)
• Reduction of spin speed for reduced formation of suds
The turbidity sensor must be calibrated (Page 56)
3 PCB
for the measurement.
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