Fanuc alarm SV0470: n AXIS:ILLEGAL RAM (MNT)
safety/dual-check alarm · Fanuc 30i/31i/32i-B
What it means
On a Dual Check Safety machine, the independent monitor CPU failed its RAM self-test for axis n. This is a hardware-level detection inside the safety-rated monitoring channel, so the system forces an immediate stop and will not release until power-cleared. Fanuc specifies replacing the axis control card.
Likely causes
- Axis control card RAM fault
- Marginal 24V supply or noise upsetting the safety monitor hardware
Triage note: (MNT) suffix marks alarms detected by the monitor side of the dual-channel safety architecture.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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Axis control card (servo card)
board · Common cause
Need the part urgently?
Send us alarm SV0470 with your machine details — typical RFQ turnaround is 24–48h.