Samsung RS257BABB Service Guide - Page 42

Circuit Descriptions 2-1) CoolSelect ZoneTM Drawer is controlled by a damper to supply or block cold air. For Quick Cool, the damper will be close. So cold air is supplied only to CoolSelect ZoneTM Drawer. For Thaw, the evaporator heater of refrigerator is ON and the damper is controlled by the refrigerator temperature. 2-2) The stepping motor controlled by a Driver IC TA7774P(IC7) operates the damper. The stepping motor uses 4 combined signals to open and close the damper. Note) To prevent the malfunction from a high humidity, a Dc12V, 1 watt heater is mounted and activated continuously. 10-8) Fan Motor (BLDC) Drive Circuit 1) Motor drive circuit 1-1) This refrigerator adopts a BLDC motor froeduce energy consumption, Motors of the freezer, refrigerator and the machine compartment are composed of the BLDC. For RS253BA, R-fan is operated by AC 115V Motor. 1-2) Voltages between high-speed and low-speed Voltage of motor Remark Measure b (F-FAN) Measure C (R-FAN) Measure d(C-FAN) In the normal operation, MICOM No. 40, 41 and 42 applies a constant frequency; and High 11.1V 10V 10V MICOM defects the signal to check the failure of motor. Low 10V 10V 8.3V (frequency(Hz)×12 = motor rpm) Note) Under the conditions, the fans will be operated in 2 options, such as High and Low mode. Generally, it is operated in the High mode during a day time and in the Low mode at night. 42