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FANUC Alarm SRVO-064 — SERVO PHAL alarm

Error
Hardware
Pulsecoder (encoder)
Controllers
R-J3iB / R-30iA / R-30iB
FANUC class
SERVO2
Hardware family
FANUC Pulsecoder, backup battery and position loss alarms

Manufacturer wording — SERVO PHAL alarm(Group:%d Axis:%d)
The manual prints placeholders; your controller fills them in with the real group, axis or number.

FANUC SRVO-064 (“SERVO PHAL alarm”): This alarm is issued when the phase of a pulse signal generated by the pulse coder is abnormal. First check: Replace the pulse coder. Likely part: Pulsecoder (Pulsecoder (motor encoder)).

Updated 2026-10-22 · LogrobotLM reference

Description

This alarm is issued when the phase of a pulse signal generated by the pulse coder is abnormal.

Remedy

Replace the pulse coder. After replacing, master the robot. NOTE: If a DTERR, CRCERR, or STBERR alarm is issued, this alarm might also be output at the same time. Should this occur, however, this alarm can be safely ignored.

Field diagnosis

The phase of the signals generated by the Pulsecoder is inconsistent.

What to check

  • If DTERR, CRCERR or STBERR are present at the same time, deal with those first: PHAL is then only a symptom.
  • Otherwise replace the Pulsecoder and redo the mastering.
  • Note: PHAL alone = encoder; PHAL with other codes = link.
  • Diagnostic sequence “Encoder link, not the encoder”: The three codes 068/069/070 appear together, sometimes with PHAL (064) or CSAL (066): the encoder serial link is at fault, and the encoder codes accompanying them are symptoms. Robot connection cable connectors at both ends, shield grounding, robot connection cable, robot internal cable; encoder and amplifier only after that. Do not replace the motor first.

Part to check / replace

FANUC SRVO-064 points to the hardware below — start here before ordering.

Tap a part for every code that points to it — and verify the exact variant for your controller before ordering.

Related codes

SRVO-068SERVO DTERR alarmSRVO-069SERVO CRCERR alarmSRVO-070SERVO STBERR alarmSRVO-071SERVO SPHAL alarmSRVO-062SERVO BZAL alarmSRVO-063SERVO RCAL alarm

Same hardware involved

SRVO-038PulsecoderSRVO-061PulsecoderSRVO-066PulsecoderSRVO-072Pulsecoder

Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →