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Fanuc alarm

SV0433 Converter DC Link Undervoltage

The DC bus voltage in the power supply module dropped too low.

Stops the machineFanuc 0i, 16i/18i/21i and 30i/31i/32i controls

What it means

The DC bus voltage in the power supply module dropped too low. The amplifiers can't run the motors without it.

Common causes

  • Dip or loss of incoming three-phase power
  • A blown fuse or loose wire on the input power
  • Failing power supply module
  • Contactor or breaker problem

What to check first

  1. Ask if other machines in the building blinked at the same time
  2. Check the main disconnect and breakers
  3. Write down the code on the power supply display

Lock out the machine before reaching into it. Never bypass a door switch or interlock to clear an alarm.

When to call a repair tech

Call an electrician or tech if the incoming power is fine and the alarm keeps returning. The power supply module may need repair.

Repair companies that work on Fanuc

See all Fanuc repair

Quick answers

What does Fanuc alarm SV0433 mean?

The DC bus voltage in the power supply module dropped too low. The amplifiers can't run the motors without it.

What causes Fanuc alarm SV0433?

Dip or loss of incoming three-phase power. A blown fuse or loose wire on the input power. Failing power supply module. Contactor or breaker problem.

How do I fix Fanuc alarm SV0433?

Ask if other machines in the building blinked at the same time. Check the main disconnect and breakers. Write down the code on the power supply display. Call an electrician or tech if the incoming power is fine and the alarm keeps returning. The power supply module may need repair.

Alarm numbers and text can differ by control model, software version and machine builder. This page is a starting point from people who have worked on these machines, not a replacement for your machine builder's manual.

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