SV0432 Converter: Control Undervoltage fault in Fanuc drive

SV0432 Converter: Control Undervoltage fault in Fanuc drive

Description

SV0432 relates to the control power supply of the PSM (Power Supply Module) or Beta-series bi-integrated amplifier. The "Converter" is the section that turns AC into DC. The control board of this unit requires a steady 24VDC to operate its logic circuits. If this internal control voltage drops below the required level (usually around 19V-21V), the processor cannot function reliable and shuts down with SV0432.

Cause

This is usually an input power problem or a failure of the auxiliary power supply.

• Input Phase Loss (Control): The PSM often has a separate small connector (CX1A) for 200V control power. If the fuse feeding this connector blows, the logic dies.
• Circuit Board Failure: The internal DC-DC converter on the PSM circuit board (which takes 200V AC and makes 24V/5V DC) has failed.
• External 24V Short: If the PSM supplies 24V to other external sensors, a short in an external sensor can drag down the PSM's internal voltage.

Solution

1. Check Fuses: Check the small glass fuses on the front of the PSM and the black fuses in the electrical cabinet that feed the control power circuit.
2. Measure Input: Check the connector CX1A (or CX2B on some units). You should see 200VAC. If you have 200VAC going in, but the alarm persists, the internal power supply of the PSM is dead.
3. Disconnect Output Loads: Unplug any I/O connectors that might be drawing 24V from the unit. If the unit powers up successfully without them, you have a short in your external wiring.