Midea 22033210000002, Руководство по обслуживанию

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Service Manual , 2016-12
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10.2 Door trip test circuit(None)
10.3 Temperature test circuit
The characteristic that resistance value reduces as the temperature increases is deemed to have negative
slope or negative temperature coefficient (NTC), and such thermostat is called as NTC thermostat. The
resistance value changes sensitively with temperature and typically changes 7% ~ 3% per degree
centigrade. Sensor used in the refrigerator is NTC thermostat.
There is following computing formula for the sensor:
Sampling voltage / reference voltage = R1 / (RNTC + R1)
AD value / reference AD value = R1 / (RNTC + R1)
The reference voltage is 5V, RNTC is the resistance value of the sensor
The sensors work rely on the resistance value changes in accordance with the temperature, by using of the
thermal couple what has resistance and coefficient of middle temperature. This kind of thermal couple
which resistance decrease following the temperature increase is call NTC(negative temperature
coefficient), the typical change of resistance value is 7%~3% per
℃，
by using the character of voltage
dividing of resistance, the specific voltage value is sent to main PCB.
In inspection, unplug the wiring connector of sensor( picture10.4, socket 1&2 )
，
adjust the multi meter
to the gear of resistance detection, put the red probe and black probe on the corresponding pins to
detect the resistance value of sensor, then check with resistance table (10.8) to identify whether the
sensor is damaged.