What the SRVO-291 alarm means

The temperature inside the intelligent power module exceeded its limit - the power stage itself is running too hot. Our engineers run into this alarm every week on FANUC R-30iA / R-30iB / R-30iB Plus controllers, and a single on-site inspection usually identifies the problem.

Most common causes

  • Failed amplifier fan or dust-blocked heatsink
  • High ambient temperature plus heavy duty cycle
  • Degraded thermal interface inside an aging amplifier
Field note: In our repair stats the first cause has the highest hit rate, so confirm it first before digging further.

Step-by-step field fix

  1. Same cooling checks as SRVO-253
  2. Monitor which axis alarms - single-axis overheating often means that amp is degrading
  3. Plan amplifier replacement if cleaning and cooling do not cure it
Safety first: For FANUC srvo-291, amplifiers and boards are live parts: hot-plugging a board burns interface circuits, and body static can kill sensitive devices. The self-serviceable action is Same cooling checks as SRVO-253; anything past that falls under live boards and power devices and needs a certified engineer.

How we diagnose amplifier/hardware alarms on site

FANUC srvo-291 belongs to the amplifier & hardware family. On FANUC srvo-291 the failing stage is alpha-i / beta-i servo amplifiers with PSM supply modules and SVM servo modules (SPM where spindles fit) on the R-30iB Plus / R-30iB Mate Plus / R-30iA - the amplifier and drive hardware itself plus its periphery: boards, fuses, cooling, supply, connectors and self-test. We start reading FANUC srvo-291 at the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code.

The chain involved in FANUC srvo-291 runs: control-side signal -> amplifier board (drive and sense circuits) -> fuses and supply -> cooling -> motor-side output.

When FANUC srvo-291 fires, clear the external causes first - Many hardware alarms are not hardware at all but external conditions: a packed filter causing over-temperature, a missing phase causing undervoltage, a loose connector causing a communication drop. Our order clears the externals first - clean, replace the mat, measure supply, re-seat terminals - near-zero cost and a high hit rate. Only when externals are gone do we judge boards or power stage. It also keeps the quotation honest: we do not sell parts we have not earned.

Field notes on this page cover FANUC srvo-291 (IPM Overheat); written by the Henghuan repair team, updated 2026-10-01.

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Related Amplifier & Hardware alarms

SRVO-057 — FSSB Disconnect SRVO-068 — DTERR - Data Transmission Error SRVO-069 — CRCERR - CRC Error SRVO-071 — SPHAL - Soft Phase Alarm SRVO-072 — PMAL - Pulse Coder Phase Alarm SRVO-073 — CMAL - Pulse Coder Count Error
Same family: this code belongs to the Amplifier & hardware alarms family - the page collects all Amplifier & hardware-family codes we have handled, with the common inspection order and spares.
Other brands: see our KUKA, ABB, Yaskawa and Universal Robots field-fix libraries — or the full 10-brand hub.

Frequently asked questions

QWhat does the FANUC srvo-291 alarm mean?

The temperature inside the intelligent power module exceeded its limit - the power stage itself is running too hot. Our engineers run into this alarm every week on FANUC R-30iA / R-30iB / R-30iB Plus controllers, and a single on-site inspection usually identifies the problem. FANUC srvo-291 sits in the amplifier & hardware family; on our work orders the highest-frequency trigger for this code is "Failed amplifier fan or dust-blocked heatsink".

QCan I clear a FANUC srvo-291 alarm myself?

Whether FANUC srvo-291 clears on its own depends on the outcome of "Same cooling checks as SRVO-253". Finish the flow with "Plan amplifier replacement if cleaning and cooling do not cure it" to confirm FANUC srvo-291 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-291 is "High ambient temperature plus heavy duty cycle". Two attempts and still there means stop: FANUC srvo-291 involves live boards and power devices, and running FANUC srvo-291 on can turn a repairable fault into a replacement.

QFor hardware alarms like FANUC srvo-291, does it always mean an expensive part swap?

The commonest causes we see on FANUC srvo-291 are "Failed amplifier fan or dust-blocked heatsink, High ambient temperature plus heavy duty cycle, Degraded thermal interface inside an aging amplifier", so we stock the van against those. For FANUC srvo-291 specifically, we carry fuses, filter mats, common connectors and terminals; boards are stocked by type or go through the repair channel. For FANUC srvo-291, on hardware alarms we inspect before quoting - we do not open with replace the power stage. Before we roll, tell us what FANUC srvo-291 shows on the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code and what the machine was doing - phone or video triage is free.

This page on FANUC srvo-291 is based on the field experience of the Henghuan Robotics repair team. Alarm explanations are our own summary for troubleshooting reference and may differ across controller and software versions — if unsure, verify against FANUC documentation or reach out to us. Henghuan is an independent service provider with no affiliation or endorsement by FANUC.