11 Inspection, Maintenance, and Troubleshooting
11-46
Position Error
(Without Alarm)
Noise interference due to incorrect
encoder cable specifications
The encoder cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
2
min.
Use the specified encoder cable.
Noise interference due to length of
encoder cable
Check the length of the encoder
cable.
The encoder cable must be no more
than 20 m.
Noise influence due to damaged
encoder cable
Check if the encoder cable is bent
and its sheath is damaged.
Replace the encoder cable and mod-
ify the encoder cable layout.
Excessive noise to encoder cable
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Change the encoder cable layout so
that no surge is applied.
The FG potential varies because of
influence from machines on the ser-
vomotor side such as the welder.
Check if the machines are correctly
grounded.
Properly ground the machines
encoder FG.
SERVOPACK pulse count error due
to noise
Check if the I/O signal line from the
encoder is influenced by noise.
Take measures against noise in the
encoder wiring.
Excessive vibration and shock to
the encoder
Check if vibration from the machine
occurred or motor installation is
incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Reduce the machine vibration or
mount the motor securely.
Unsecured coupling between
machine and motor
Check if a position error occurs at
the coupling between machine and
motor.
Secure the coupling between the
machine and motor.
Noise interference due to improper
I/O signal cable specifications
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
2
min.
Use input signal cable with the
specified specifications.
Noise interference due to length of
I/O signal cable
Check the I/O signal cable length.
The I/O signal cable length must be
no more than 3 m.
Encoder failure (The pulse count
does not change.)
−
Replace the motor.
SERVOPACK failure
−
Replace the SERVOPACK.
Motor Overheated
Ambient operating temperature too
high
Measure the motor ambient operat-
ing temperature.
Reduce the ambient operating tem-
perature to 40
°
C or less.
Motor surface dirty
Visually check the surface.
Clean dust and oil from the surface.
Motor overloaded
Check the load status with monitor.
If overloaded, reduce load or
replace with larger capacity SER-
VOPACK and motor.
(cont’d)
Problem
Probable Cause
Investigative Actions
Corrective Actions
