Fanuc alarm 04
αi PSM · Fanuc αi PSM
What it means
In the main circuit the DC voltage (DC link) has dropped.
Likely causes
- Small power dip / brown-out
- Low input supply voltage
- Main circuit switched off with emergency stop released (sequence fault)
- Loose DC link bus bar between PSM and SVM/SPM
Triage note: Check incoming 3-phase supply and MCC sequence first; rarely a failed PSM. If several modules show low DC link simultaneously the root cause is upstream. Mirrors as SP0051 / 9051.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
- View part →
A06B-6087-H126
Power Supply Module αi PSM (only after supply/sequence checks pass) · Check if others ruled out
Need the part urgently?
Send us alarm 04 with your machine details — typical RFQ turnaround is 24–48h.