Fanuc spindle alarm codes A, A1 and A2 mean the amplifier's control program is not running — or an error was detected while it ran. The spindle amplifier's own firmware crashed or never started. Fanuc splits the causes by when it appears:
Case 1 — At power-on
- Wrong software specification: the control software on the board does not match the amplifier — almost always the aftermath of a board swap or reflash with the wrong series/edition (the AL-14 mixed-board lesson in its bluntest form). Verify board pedigree before condemning hardware.
- Defective control PCB: the board's processor environment cannot run its program — board-level repair (RAM, storage, regulators) or exact-spec exchange. One clean power cycle and a firm faceplate reseat first, per the standing rule.
Case 2 — While the motor is active (mid-operation crash)
Noise. Fanuc sends you to the Installation section of B-65282EN: check the grounding wire, and if the spindle sensor signal cable is bundled with any motor power wire, separate them. A running control program knocked over by interference points at the cabinet's grounding and routing — the same two disciplines behind half the alarms in this library. Check the ground wire's condition and torque, and walk every signal cable's routing.
Tip: A-codes at every power-on → software/board — bench territory. Random A-codes during heavy cutting on a machine with a history of communication alarms (AL-24 family) → the cabinet has a grounding/noise problem that is now crashing processors — fix the environment, not the amplifier.
Related guides
- Fanuc spindle alarms 13 & 14 (board self-tests)
- Fanuc spindle alarm 24 (noise and routing)
- Fanuc αi drive alarms index
A / A1 / A2 on your amplifier? JJ Automation repairs control boards with correct software editions, and diagnoses cabinet grounding and noise on site in NCR. WhatsApp us or call +91 88022 12394.