SV0433Servo alarm · Power supply (PSM)Usually repairable
Fanuc αi SV0433: Converter DC Link Undervoltage
Also shown as: PSM display 4; 16i/18i/21i/0i: 433
What SV0433 means
The DC link voltage from the power supply (PSM) dropped too low. Shown on the PSM as 4.
Symptoms
Alarm during heavy acceleration or on supply dips.
Is it repairable?
Yes, when the PSM is the cause.
Common causes
- Supply voltage dip or missing phase
- Main contactor (MCC) problem
- PSM rectifier or capacitor fault
Safe checks
- 1Measure all three supply phases under load
- 2Inspect the MCC contactor
- 3Check the incoming fuses
Drives hold dangerous voltage after power-off. Checks should only be done by qualified personnel, with power isolated and the DC link discharged.
Reviewed by AutomIQ repair technicians. Code and name from the FANUC αi series Maintenance Manual.
Related Fanuc αi faults
- SV0368Serial data error (built-in)
- SV0401V ready off
- SV0436Soft thermal (OVC)
- SV0438motor current alarm
- SV0442DC link precharge failure
- SV0443cooling fan stopped