Chapter 5
5-9
Troubleshooting
Overspeed Occurs when the 
servo is ON.
Encoder signal between 
controllers is wired incor-
rectly.
Rewire correctly.
Servomotor power line is 
wired incorrectly.
Rewire correctly.
Occurs along with 
high-speed rota-
tion when a com-
mand is input.
Position command input 
exceeds 4,500 r/min.
Input command values cor-
rectly.
Pn202 and Pn203 (elec-
tronic gear ratio) setting is 
too large.
Set the parameters correctly.
Resolution setting switch 
(switches 4 and 5) setting is 
too low.
Reset the switches correctly.
Rotation limit has been 
exceeded due to over-
shooting.
Adjust the gain.
Lower the maximum specified 
speed.
Overload Occurs during 
operation.
Running at over 120% of 
rated torque (effective 
torque).
Repair the Servomotor shaft if 
it is locked.
If the Servomotor power line is 
wired incorrectly, rewire it cor-
rectly.
Lighten the load.
Lengthen the acceleration and 
deceleration times.
Adjust the gain.
Power supply voltage has 
fallen.
Check the power supply volt-
age, and lower to within toler-
ance range.
Servomotor winding is 
burned out.
Check the winding resistance. 
Replace the Servomotor if the 
winding is burned out.
Servo Driver is burned out. Replace the Servo Driver.
Dynamic 
brake over-
load
Occurs when the 
servo is turned 
OFF after operat-
ing.
Energy required for stop-
ping exceeds the dynamic 
brake resistor tolerance.
Lower the rotation speed.
Reduce the load inertia.
Reduce the frequency of 
dynamic brake use.
Occurs when the 
power supply is 
turned ON.
Control panel error Replace the Servo Driver.
Inrush resis-
tance overload
Occurs when the 
main circuit power 
supply is turned 
ON.
The frequency by which 
main-circuit power supply is 
turned ON and OFF 
exceeds 5 times/min.
Reduce the frequency by which 
the main circuit power supply is 
turned ON and OFF.
Occurs when the 
control circuit 
power supply only 
is turned ON. 
Control panel error Replace the Servo Driver.
Display Error Status when 
error occurs
Cause of error Countermeasures
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