SRVO-157: CHGAL alarm (capacitor charge failure)
When servo power engaged, the amplifier's DC bus capacitors didn't charge within the allowed time.
What it means
When servo power engaged, the amplifier's DC bus capacitors didn't charge within the allowed time. Rich cause list ranging from low input voltage to a tripped breaker to a specific system-variable trap on auxiliary axes.
Common causes
Ranked by what technicians most often find, most likely first.
- Aux-axis trap: $SCR_GRP[g].$AXISORDER changed manually - a documented trigger.
- Input voltage low or missing a phase at servo-on; wrong transformer setting.
- Tripped circuit breaker on the E-stop unit.
- Loose CRRA12 connectors (amplifier, E-stop board, and αiPS if fitted).
- Aux-axis reset-timing quirk: RESET within 2 seconds of an E-stop-type signal.
- Hardware: αiPS, 6-axis amplifier, E-stop unit.
How to fix it
- If anyone changed $AXISORDER, restore the original value. If it is lost, stop and contact FANUC with the alarm details.
- With the controller de-energized and locked out, confirm the transformer setting matches the site supply and that every supply conductor is landed and tight at the input terminals. If the incoming supply itself is suspect, it has to be checked upstream at the disconnect by a qualified electrician under the site's energized-work procedures, not by probing inside the robot cabinet.
- With the controller de-energized and locked out, check that the E-stop unit breaker has not tripped.
- With the controller de-energized and locked out, reseat every CRRA12 connector in the chain.
- Enforce the 2-second E-stop-to-RESET gap on auxiliary systems.
- If it still alarms, replace the power supply, amplifier, and E-stop unit in that order, each with the controller de-energized and locked out. Power-cycle to clear.