Electrolux EW27MO55HSA, Техническое и сервисное руководство

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Operation
2-6
(3) Detector Circuit of Absolute Humidity Sensor
Circuit:
This detector circuit is used to detect the output
voltage of the absolute humidity circuit to allow the
LSI to control sensor cooking of the unit. When the
unit is set in the sensor cooking mode, 16 seconds
clearing cycle occurs then the detector circuit starts
to function and the LSI observes the initial voltage
available at its AN6 terminal.
With this voltage given, the switches SW1 to SW5 in
the LSI are turned on in such a way as to change the
resistance values in parallel with R50-1. Changing
the resistance values results in that there is the same
potential at both F-3 terminal of the absolute
humidity sensor and AN7 terminal of the LSI. The
voltage of AN6 terminal will indicate about -2.5V.
This initial balancing is set up about 16 seconds after
the unit is put in the Sensor Cooking mode.
As the sensor cooking proceeds, the food is heated
to generate moisture by which the resistance
balance of the bridge circuit is deviated to increase
the voltage available at AN6 terminal of the LSI.
Then the LSI observes that voltage at AN6 terminal
and compares it with its initial value, and when the
comparison rate reaches the preset value (fixed for
each menu to be cooked), the LSI causes the unit to
stop sensor cooking; thereafter, the unit goes in the
next operation automatically.
When the LSI starts to detect the initial voltage at
AN6 terminal 16 seconds after the unit has been put
in the Sensor Cooking mode, if it is not possible to
balance, of the bridge circuit due to disconnection of
the absolute humidity sensor, ERROR will appear on
the display and the cooking is stopped.
1) Humidity sensor circuit:
SW2
SW1
SW3
SW4
SW5
P30
P31
P32
P33
P34
LSI
(IC1)
AN7
AN6
620k
300k
150k
75k
37.4k
4
64
5 63
6
7
8
62
61
60
3
5
2
6
47k
47k
10k
0.01µF
0.015µF
0.01µF
360k
+
-
1 12
VA : -15V
VA : -15V
R51
9
S
F-2
10
1.8k
F-1
F-3
C
11
3.57k
3.32k
VC : -5V
0.1 µF
C. Thermistor in
closed vessel
S. Thermistor in
open vessel
IC2(IZA495DR)