14.2  Alarm Displays
14.2.2  Troubleshooting Alarms
14-24
A.7Ab: 
SERVOPACK 
Built-in Fan 
Stopped
The fan inside the 
SERVOPACK 
stopped.
Check for foreign matter 
inside the SERVOPACK.
Remove foreign matter 
from the SERVOPACK. If 
an alarm still occurs, the 
SERVOPACK may be 
faulty. Replace the SER-
VOPACK.
–
A.810: 
Encoder Backup 
Alarm 
(Detected at the 
encoder, but only 
when an abso-
lute encoder is 
used.)
The power to the 
absolute encoder was 
turned ON for the first 
time.
Check to see if the 
power supply was 
turned ON for the first 
time.
Set up the encoder.
page 5-46
The Encoder Cable 
was disconnected 
and then connected 
again.
Check to see if the 
power supply was 
turned ON for the first 
time.
Check the encoder con-
nection and set up the 
encoder.
Power is not being 
supplied both from 
the control power 
supply (+5 V) from the 
SERVOPACK and 
from the battery 
power supply.
Check the encoder 
connector battery and 
the connector status.
Replace the battery or 
implement similar mea-
sures to supply power to 
the encoder, and set up 
the encoder.
A failure occurred in 
the absolute encoder.
–
If the alarm still occurs 
after setting up the 
encoder again, replace 
the Servomotor.
–
A failure occurred in 
the SERVOPACK.
–
The SERVOPACK may be 
faulty. Replace the SER-
VOPACK.
–
A.820: 
Encoder Check-
sum Alarm 
(Detected at the 
encoder.)
A failure occurred in 
the encoder.
–
 When Using an Abso-
lute Encoder
Set up the encoder again. 
If the alarm still occurs, 
the Servomotor may be 
faulty. Replace the Servo-
motor.
 When Using a Single-
turn Absolute Encoder 
or Incremental Encoder
• The Servomotor may be 
faulty. Replace the Ser-
vomotor.
• The linear encoder may 
be faulty. Replace the 
linear encoder.
page 5-46
A failure occurred in 
the SERVOPACK.
–
The SERVOPACK may be 
faulty. Replace the SER-
VOPACK.
–
A.830: 
Encoder Battery 
Alarm 
(The absolute 
encoder battery 
voltage was lower 
than the speci-
fied level.)
The battery connec-
tion is faulty or a bat-
tery is not connected.
Check the battery con-
nection.
Correct the battery con-
nection.
page 4-26
The battery voltage is 
lower than the speci-
fied value (2.7 V).
Measure the battery 
voltage.
Replace the battery.
page 14-3
A failure occurred in 
the SERVOPACK.
–
The SERVOPACK may be 
faulty. Replace the SER-
VOPACK.
–
Continued on next page.
Continued from previous page.
Alarm Number: 
Alarm Name
Possible Cause Confirmation Correction Reference