SRVO-157: CHGAL alarm (capacitor charge failure)

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.

1. Aux-axis trap: $SCR_GRP[g].$AXISORDER changed manually - a documented trigger.
2. Input voltage low or missing a phase at servo-on; wrong transformer setting.
3. Tripped circuit breaker on the E-stop unit.
4. Loose CRRA12 connectors (amplifier, E-stop board, and αiPS if fitted).
5. Aux-axis reset-timing quirk: RESET within 2 seconds of an E-stop-type signal.
6. Hardware: αiPS, 6-axis amplifier, E-stop unit.

How to fix it

1. If anyone changed $AXISORDER, restore the original value - and if it's lost, stop and contact FANUC with the alarm details.
2. Measure input voltage at servo-on; verify all phases present and transformer setting correct.
3. Check the E-stop unit breaker hasn't tripped.
4. Reseat every CRRA12 connector in the chain.
5. Enforce the 2-second E-stop-to-RESET gap on aux systems.
6. Then hardware: power supply, amplifier, E-stop unit. Power-cycle to clear.

Related codes

• SRVO-156IPMAL alarm (overcurrent)
• SRVO-170Lack of DSP
• SRVO-138SDAL alarm (pulse coder signal error)
• SRVO-136DCLVAL alarm (aux amplifier DC link low)
• SRVO-135FSAL alarm (aux amplifier fan stopped)
• SRVO-134DCLVAL / DCLVAL (PS) alarm (DC link voltage low)
• SRVO-133FSAL (PS) alarm (power supply fan stopped)
• SRVO-182Needed init. has not been done