9 - 10
9. TROUBLESHOOTING
Display Name Definition Cause Action
1. Machine struck something. 1. Review operation pattern.
2. Install limit switches.
2. Wrong connection of servo motor.
Servo amplifier's output terminals
U, V, W do not match servo
motor's input terminals U, V, W.
Connect correctly.
3. Servo system is instable and
hunting. 1. Repeat acceleration/
deceleration to execute auto tuning.
2. Change auto tuning response setting.
3. Set auto tuning to OFF and make gain
adjustment manually.
A. 51 Overload 2 Machine collision or
the like caused max.
output current to
flow successively for
several seconds.
Servo motor locked:
1s or more
4. Encoder faulty.

When the servo motor shaft is

rotated slowly with the servo off,

the cumulative feedback pulses

should vary in proportion to the

rotary angle. If the indication

skips or returns midway, the

encoder is faulty.

Checking method Change the servo motor.
1. Acceleration/deceleration time
constant is too small. Increase the acceleration/deceleration
time constant.
2. Torque limit value (parameter
No.28) is too small. Increase the torque limit value.
3. Motor cannot be started due to
torque shortage caused by power
supply voltage drop.
1. Review the power supply capacity.
2. Use servo motor which provides larger
output.
4. Position control gain 1 (parameter
No.6) value is small. Increase set value and adjust to ensure
proper operation.
5. Servo motor shaft was rotated by
external force. 1. When torque is limited, increase the
limit value.
2. Reduce load.
3. Use servo motor that provides larger
output.
6. Machine struck something. 1. Review operation pattern.
2. Install limit switches.
7. Encoder faulty Change the servo motor.
A. 52 Error excessive Droop pulse value of
the deviation
counter exceeded
80k pulses.
8. Wrong connection of servo motor.
Servo amplifier's output terminals
U, V, W do not match servo
motor's input terminals U, V, W.
Connect correctly.