Temperature Sensing Circuit Part - Samsung RL44Q Series Service Manual

5. SELF DIAGNOSIS & TROUBLE SHOOTING REFERENCE INFORMATION

9-3-1-6) Temperature Sensing Circuit Part

1) Temperature sensing (sensor part) is described with Fig. 1-1.
2) Using the Thermistor(Sensor) which has temperature coefficient of the negative resistance,
the higher temperature the resistance is reduced and reversely the lower temperature the
resistance is increased.
3) Regarding Freezer sensor, if the voltage input into MICOM is Vf, Vf = (Rth X Vcc) /
(Rpu(R301) + Rth) Rth is the resistance value of the thermistor corresponding to
temperature. Refer to the table in this manual showing the resistance of the sensor
corresponding to the temperature and the value converted to the voltage. As it also has the
terminal voltage of the MICOM, refer to this on after sales service. (Rth is the resistance
value of the sensor. As this value is changed by the temperature of the sensor, refer to the
resistance value of the sensor corresponding to the temperature)
4) As all temperature sensors applied to the refrigerator are running in the way above, you can
check the Sensors for the chammart compartment, defrosting, refrigerating, and the ambient
temperature in the same way.
(Rpu)
This devided
voltage is detected
by MICOM
Temperature
Sensor
< Fig-2 The equivalent circuit of the sensor's action >
< Fig.1-1 Circuit Diagram for sensor part >
(Vcc)
The terminals on the MICOM
#54(Freezer sensor)
#53(F-DEF-Sensor)
#52(FRIDGE SENSOR)
#51(Chammart
Compartment-Sensor)
#57(Ambient
Temperature-Sensor)
178
Voltage
The change
of the terminal
voltage on
MICOM
corresponding
to the
temperature