Fagor alarm 4177: ERROR 315: The power supply has not started up correctly

What it means

The power supply failed its start-up sequence, so the DC bus never reached the ready state. PWM is cut (category 0 stop) and the whole CNC remains shut down. For PS-25x supplies Fagor specifically calls out the ballast resistor; otherwise inspect the supply itself.

Likely causes

• Open or degraded ballast resistor (esp. PS-25x)
• Soft-start/precharge circuit failure in the PSU
• Weak mains input or blown input fuse
• Internal PSU control fault

Replacement parts

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

• Ballast resistor

  regen-resistor · Common cause

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• PS / XPS power supply

  power-supply · Common cause

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