Alarms 13 and 14 on a Fanuc spindle amplifier are internal self-test failures — the amplifier's own brain reporting that something is wrong with itself:
- AL-13 — an error was detected in the CPU's internal RAM. The control processor's memory failed its check.
- AL-14 — the amplifier ID data is inconsistent with the series and edition of the software. The hardware identity stored in the unit does not match the control software running on it.
Fanuc's remedy for both is one line: ‘the Spindle Amplifier is abnormal — replace it.’ True but incomplete. These alarms almost always appear at power-on (the self-test runs at boot), and before condemning a unit — or after one comes back from a questionable repair — there are things worth knowing.
AL-13 — CPU internal RAM error
What it means: the control board's processor found corrupt/failed RAM during its self-check. The power stage may be perfectly healthy — this is a control-board-level fault.
- Power-cycle once, cleanly: a single marginal boot (brown-out during power-up, control voltage sag — see AL-10) can fail the self-test spuriously. Full power off, wait for the charge LED, power on. Once. If it returns, it's real — do not keep cycling and hoping.
- Reseat the control board faceplate: the recurring theme of this series — a half-seated board-to-board connector can corrupt the CPU's environment. Push the faceplate fully home (power off, locked out).
- Recurring AL-13 → the control PCB needs repair or replacement. On the bench this is usually a failed RAM chip, a corrupted CPU environment from a failing onboard regulator, or heat-aged solder joints — all repairable at board level, considerably cheaper than a complete amplifier. If the machine is down, an exchange unit is the fast path.
AL-14 — Amplifier ID vs software mismatch
What it means: every αi amplifier carries ID data describing its model and ratings; the control software (series/edition) must be compatible with it. AL-14 says they disagree — and unlike AL-13, this alarm is usually man-made. It appears almost exclusively after someone has been inside:
- Mixed boards: a control board from one amplifier model fitted to another's power unit — the classic ‘Frankenstein’ field repair. The board boots, reads the power unit's ID, and refuses the marriage.
- Wrong replacement board: visually identical control PCBs exist across amplifier ratings and generations with different software — an A-number that almost matches is not a match.
- Software series/edition mismatch after a board was reflashed or pulled from stock with older/newer firmware than the unit family requires.
- Corrupted ID data — rarer: the ID storage itself has failed, often alongside other odd symptoms.
The fix: restore a consistent pairing — the correct control board (exact specification, not just same-looking) with the correct software for the power unit. If AL-14 appeared on a unit that came back from repair elsewhere, send it back: the repairer fitted an incompatible board. This is exactly why we bench-test repaired units against their own model's spec before dispatch.
Buying used amplifiers? Read this first
AL-14 is disproportionately common on second-hand amplifiers assembled from mixed donors. When buying used/refurbished units, insist on: the full A06B part number matching your dead unit, a photo of the ID/nameplate, and a load-test report. Our used-parts buying checklist covers the rest.
Diagnosis checklist (in order)
- Note WHEN the alarm first appeared: untouched machine vs after repair/swap/purchase.
- One clean power cycle; verify control voltage is healthy (no AL-10 history).
- Reseat the control board faceplate fully.
- AL-13 persists → control PCB repair (RAM/regulator) or exchange unit.
- AL-14 persists → verify board pedigree: exact model, software series/edition — correct the pairing, or return the unit to whoever created it.
Related guides
- Fanuc spindle alarm 10 (control power voltage low)
- Fanuc αi drive alarms — PSM, SVM & SPM codes explained
- Buying used/refurbished CNC parts — what to check