Fanuc alarm b1, b2, b3: Converter alarms mirrored from PSM

What it means

Codes b1 (converter control power low), b2 (excessive regenerative power) and b3 (converter radiator fan stopped) appearing on the αi SPM status display indicate the alarm originated in the PSM. Always troubleshoot using the PSM's 7-segment display.

Likely causes

• PSM 24 V control supply drop (b1)
• Regenerative power overload in PSM (b2)
• PSM radiator cooling fan failure (b3)

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• A06B-6110-Hxxx / A06B-6120-Hxxx (PSM components per code)

  power-supply · Common cause

  Request a quote →