FANUC Alarm LECO-050 — Cap A under voltage (Cap A volts, Cap B volts)
FANUC LECO-050 (“Cap A under voltage (Cap A volts, Cap B volts)”): The voltage on one of the two input capacitor banks (bank A) has fallen below the normal operating limit. First check: Check the input power (voltage and frequency).
Updated 2026-09-17 · LogrobotLM reference
Description
The voltage on one of the two input capacitor banks (bank A) has fallen below the normal operating limit. This is normally caused by low input voltage or a missing phase (with 3 phase input power) but it could be caused by a faulty switch board, main capacitor, contactor, or V-to-F feedback signal.
Remedy
Check the input power (voltage and frequency). Verify the primary reconnect is properly configured for the input voltage.
Related codes
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →