Fanuc alarm SV0446: HARD DISCONNECT ALARM

What it means

Hardware-level detection found the built-in pulse coder disconnected — the amplifier stopped receiving feedback pulses entirely, not merely corrupted ones. Check the feedback cable seating at the motor rear cover and at the amplifier first; broken conductors inside the cable near flexing points are frequent. If a known-good cable doesn't clear it, the pulse coder has failed.

Likely causes

• Feedback cable unplugged, cut, or broken at flex point
• Connector pin damage/retraction at motor or amplifier end
• Built-in pulsecoder failure
• Missing feedback supply from amplifier side

Replacement parts

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

• A860-2000-T301

  pulse-coder · Common cause

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• A860-2070-T301

  pulse-coder · Common cause

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