V4
DC Link Not Charged
Fanuc · R-30iB Mate + Mate Plus Robot
What does V4 mean?
The V4 (Red) LED indicates that the DCLINK circuit inside the servo amplifier is charged to the specified voltage. If this LED does not light after the pre-charge sequence is finished, it suggests a problem with the DC link charging, potentially due to a short circuit or a defective charge current control resistor.
Repair Steps
- 1
Check the DC Link circuit for a short-circuit connection.
- 2
Replace the emergency stop unit, as the charge current control resistor may be defective within it.
- 3
Replace the servo amplifier.
Verified technical data. Last updated: March 2026
Source: Fanuc R-30iB Mate + Mate Plus Robot