Mitsubishi Electric MELSERVO-J4 Series Transition Handbook page 643

Part 9: Review on Replacement of Optional Peripheral Equipment
(4) Battery replacement procedure
WARNING
CAUTION
Replace the battery while only control circuit power is on. Replacing battery with the control circuit power
on triggers [AL. 9F.1 Low battery]. However, the absolute position data will not be erased.
Before replacing a battery, turn off the main circuit power and wait for 15 minutes
or longer until the charge lamp turns off. Then, check the voltage between P+ and
N- with a voltage tester or others. Otherwise, an electric shock may occur. In
addition, when confirming whether the charge lamp is off or not, always confirm it
from the front of the servo amplifier.
The internal circuits of the servo amplifier may be damaged by static electricity.
Always take the following precautions.
Ground human body and work bench.
Do not touch the conductive areas, such as connector pins and electrical parts,
directly by hand.
POINT
Replacing battery with the control circuit power off will erase the absolute
position data.
Before replacing batteries, check that the new battery is within battery life.
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