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What This Guide Helps With
This guide helps troubleshoot the ACB UNEXPECTED RESET alarm on a GE Healthcare Aisys anesthesia machine. This alarm indicates an unexpected Anesthesia Control Board reset, which may cause system malfunction, unexpected reboot behavior, loss of normal screen function, or interruptions to anesthesia machine control.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Confirm whether the anesthesia machine is connected to an active patient.
- If the alarm occurs during clinical use, notify anesthesia staff immediately.
- Have anesthesia staff transfer the patient to another anesthesia machine, manual ventilation setup, or appropriate backup ventilation method if needed.
- Do not continue using the machine for patient care with an unresolved system malfunction or control board reset alarm.
Verify the Reported Alarm and Behavior
- Confirm the displayed alarm is ACB UNEXPECTED RESET.
- Check whether the alarm appears during startup, system checkout, active use, after a power interruption, or intermittently with no clear pattern.
- Observe for associated symptoms such as a system malfunction message, unexpected reboot, loss of normal screen function, ventilator interruption, or repeated alarm after restart.
- Document the exact timing and behavior before attempting repeated resets.
Check AC Power Source
- Verify the anesthesia machine is connected to a known-good hospital-grade AC outlet.
- Confirm the power cord is fully seated at the wall outlet and at the machine.
- Check whether the machine recently lost power, was unplugged, or switched to battery operation.
- If safe and appropriate, test the outlet or move the machine to a verified working outlet.
Check Power Cord and External Power Condition
- Inspect the power cord for loose connection, damaged insulation, bent plug blades, overheating, or intermittent connection when moved.
- Do not use the machine if the cord or plug shows damage.
- Confirm the power connection remains stable when the cord is gently repositioned.
Check for Recent Events Before the Alarm
- Ask staff what happened immediately before the alarm appeared.
- Look for recent power outage, machine movement between rooms, accidental unplugging, startup after storage, alarm during checkout, or alarm after accessory/module connection.
- Note whether the alarm followed a clear external event or occurred randomly with no user action.
Reboot the System
- Power the Aisys system down using the proper shutdown process.
- Wait briefly, then restart the system.
- Allow the machine to complete startup.
- Observe whether the ACB UNEXPECTED RESET alarm returns.
Run or Repeat System Checkout
- If the alarm clears after reboot, perform the required anesthesia machine checkout according to facility procedure.
- Watch for alarm recurrence, system malfunction messages, ventilator issues, failed checkout steps, or unexpected restart during testing.
- Do not return the machine to service unless checkout completes successfully and the alarm does not return.
Check Whether the Alarm Is Repeatable
- If the alarm returns, note exactly when it happens.
- Examples include immediately at startup, during checkout, when ventilation begins, after several minutes powered on, when moved or touched, or randomly with no clear trigger.
- A repeatable ACB reset alarm strongly suggests a device-level control issue rather than a simple external cause.
Isolate External Causes Before Calling the ACB Failed
- Confirm AC power is stable.
- Confirm the power cord is secure and undamaged.
- Confirm no obvious external damage is present.
- Confirm the alarm returns after reboot.
- Confirm the alarm is not tied to a known power interruption.
- Confirm the system cannot reliably complete checkout if the alarm persists.
Stop When Resolved
- If the alarm clears after reboot, AC power is stable, and the system passes checkout, return the machine to service according to facility policy.
- Document the alarm, reboot, checkout result, and final status in the work order.
- Do not replace internal boards based on one alarm event without checking basic power and operating conditions first.
If the Problem Persists
If the ACB UNEXPECTED RESET alarm returns after reboot and external power issues have been ruled out, the condition may indicate an internal device failure involving the Anesthesia Control Board or related control circuitry.
- Remove the anesthesia machine from service.
- Label it Out of Service.
- Do not return it to patient use.
- Send it for repair or bench evaluation.
- Replace or repair internal components only if confirmed appropriate by service procedure.
Clinical Use Tip
Never troubleshoot an anesthesia machine with an unresolved system malfunction alarm on an active patient. Move the patient to backup equipment first, then continue troubleshooting only when it is safe to do so.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"GE Healthcare Aisys anesthesia machine reported ACB UNEXPECTED RESET alarm. Staff reported system malfunction and unexpected reset during startup or checkout."
Cause
What was observed during troubleshooting.
Example:
"Alarm confirmed. External AC power and power cord checked. System reboot performed. Alarm cleared after reboot, or alarm returned after external power issues were ruled out."
Resolution
What action was taken.
Example:
"Rebooted system, verified AC power connection, and repeated system checkout. If checkout passed and alarm did not return, device was returned to service. If alarm returned, device was removed from service and sent for repair or ACB evaluation."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
An ACB UNEXPECTED RESET alarm should be treated as a control system reliability issue. Start with patient safety, verify the alarm, rule out simple power problems, reboot the system, and confirm proper operation through checkout. If the alarm persists, remove the machine from service and escalate for repair. Good troubleshooting protects the patient, the clinical team, and the equipment record.
That is successful troubleshooting.