**Analysis and Repair**: Referring to the random manual, code E9 indicates a failure in the automatic weighing system. A preliminary judgment suggests there is an issue with the weighing circuit.
When the water level reaches the preset level, the microprocessor continuously emits on-off pulses within a certain period of time, driving the washing motor to operate. After the motor is powered off, its rotor continues to rotate under the influence of inertia, generating an induced voltage on the coil. The amplitude, frequency, and duration of this voltage are directly proportional to the size of the inertial rotational speed and the rotation time. The induced voltage generated on the motor coil is transmitted via R16, D10, and optocoupler PC1. The optocoupler PC1 sends out photoelectric pulses, which are then amplified and reshaped by Q9 and Q5, limited by R42, and filtered by C24 before being sent to pin (47) of microprocessor IC1. The microprocessor counts the number of these pulses and compares it with the analog quantities designed in its internal program for high, medium, and low clothing loads, thus accurately measuring the amount of laundry. Based on the above principle analysis, the focus should be on checking the signal detection part. First, disconnect the gray and blue plugs controlling the motor operation on the printed circuit board, and then use a multimeter at the R1K range for testing. It was found that terminals a and b on the circuit board were in an open-circuit state. Further stripping of the relevant silicone rubber revealed that resistor R16 had been damaged and was in an open-circuit condition.
**Fault Phenomenon**: After turning on the machine, an alarm sounds inside, and the E9 code appears in the display window.
**Xiao Tian'e XQB40-868FC Washing Machine Displays E9**
**Source of Article**: Beijing Xiao Tian'e Washing Machine After-sales Service Phone [http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3446359](http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3446359).
**Resolution Measures**: Replace the faulty component with a 100KΩ/5W resistor, and after testing the machine, the fault was eliminated.