The motor still runs at low speed after servo off.
The servo speed is given by the analog voltage in speed mode. When the equipment is switched from the running state to the stop state (the analog voltage drop is 0V), the servo motor continues to run at low speed.
SD600A analog input null drift is too large that leads to that motor runs in low speed because the null-drift "think" that input signal is not 0 when the external analog input is exactly 0V.
Adjust the analog offset according to the actual zero drift size and positive or negative value.
When the servo works normally, the external input is 0V, but there is actually a few millivolts of deviation, but with 10V corresponding to 3000r/min, the torque of several millivolts corresponding to the speed is not enough to overcome the resistance torque of the motor itself, so the servo drive can normally operate, but at this time, with the null drift of the servo drive itself (above 10mv), the sum of the two voltages corresponding to the rotational speed torque exceeds the resistance torque, and the performance is 0, the motor would run at low speed.