FANUC Alarm SRVO-072 — SERVO PMAL 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 PMAL alarm(Group:%d Axis:%d)
The manual prints placeholders; your controller fills them in with the real group, axis or number.
FANUC SRVO-072 (“SERVO PMAL alarm”): The pulse coder might be faulty. First check: Replace the pulse coder, then master the robot. Likely part: Pulsecoder (Pulsecoder (motor encoder)).
Updated 2026-10-22 · LogrobotLM reference
Description
The pulse coder might be faulty.
Remedy
Replace the pulse coder, then master the robot.
Field diagnosis
The Pulsecoder is very probably out of service.
What to check
- Replace the Pulsecoder, then redo the mastering.
- Note: Few false positives on this code.
- Diagnostic sequence “Battery box / motor”: BZAL that returns after the batteries have been replaced: the message says "batteries", but the cause is not the battery. Discriminating test 1: battery box contact springs (sagged → no more contact despite good batteries). Discriminating test 2: swap the encoder cables of two axes and reset; if the fault follows the cable, it is the cable; if it stays on the axis, it is the encoder/motor.
Part to check / replace
FANUC SRVO-072 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
Same hardware involved
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 →