E013—HALL_A Signal failure

(If the motor speed higher than 50rpm, HALL_A is signal keeps continuous 1s low frequency or high frequency, that means the frequency without change for continuous 1s)

Step of solution:
1）check The encoder socket and the main control board  encoder connect
2）check the impedance on encoder board U3—pin 2 to pin 3; around 1.2M;【Standby voltage：follow the angle of raster changing,switch 0V and 5.1V】; impedance【earth】  of U3—pin 4 to pin 3：about 20K.【Standby voltage：1.2V】 ,U3—pin 2 and J1（1pin ）is breakover or not.【Remark：when encoder is connecting main control, above impedance is different】
3）Gauge C29 two-terminals impedance on main control board：around 11K ；【Standby voltage：5.1V】； U2（38 pins）or U6—pin 14 to C4 impedance on negative terminal：about 3M【Standby voltage：3.2V】
4）check the C29 two-terminal impedance on main control board: about 11K .(Standby voltage:5.1V); U2(38 pin) or U6-14 pin to impedance on C4 negative terminal: around 3M (Standby voltage:3.2V)
5）check the C39 two-terminal impedance on main control board: about 11K.(Standby voltage:5.1V); U2(52 pins) or U6-18 pins to impedance on C4 negative terminal: 3M detection(Standby voltage:3.2V)
6）check the C41 two-terminal impedance on main control board: about 11K.(Standby voltage:5.1V); U2(64 pins) or U6-7 pins to impedance on C4 negative terminal: around 3M (Standby voltage:3.2V)