Applicable Systems
Series 0i
Series 16/18/21
Alpha
Beta
Symptoms
A digital servo feedback error was detected. The position feedback data from the servo motor encoder may be corrupted. Alarm SV 461 is displayed for the 4th axis.
Possible Causes
- 4th axis encoder feedback cable damaged or disconnected
- 4th axis servo amplifier feedback circuit fault
- Servo motor encoder internal failure
- Electromagnetic interference on feedback signal lines
Troubleshooting Steps
- Step 1: Check 4th axis encoder cable and connectors
Cable intact, connectors clean and seated - Step 2: Verify 4th axis encoder signal with oscilloscope if available
Clean pulse signal observed on oscilloscope - Step 3: Check for EMI sources near the feedback cable routing
No significant EMI sources identified, cable shielded properly - Step 4: If encoder suspected faulty, replace servo motor or encoder
New encoder provides clean feedback signal
How to Reset
Power off, check encoder cable and connectors, verify signal integrity, power on. Replace encoder or servo motor if confirmed faulty. Clear alarm with RESET.
Common Replacement Parts
- varies: 4th axis servo motor with integrated encoder (Confirm motor model before ordering)
Frequently Asked Questions
- Q: What does Fanuc SV 461 4th mean?
Feedback Digital: A digital servo feedback error was detected. The position feedback data from the servo motor encoder may be corrupted. This alarm is specific to the 4th axis feedback circuit.
- Q: How do I fix SV 461?
Check the encoder cable and connectors, verify signal integrity, check for EMI. If the encoder itself is faulty, the servo motor or encoder unit needs replacement.
Source: Fanuc 0i Servo Alarm Code List (Supplement), FANUC Corporation
Category: CNC