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Model
What This Guide Helps With
Error 120.4340 indicating high 5V supply voltage, causing PC unit failure, module communication issues, or system shutdown.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Stop infusion immediately
- Transfer therapy to another functioning pump or system
2. Verify the Reported Error and Behavior
- Power on the Alaris PC unit
- Confirm Error 120.4340 is displayed
- Observe startup behavior and responsiveness
- Check if modules power on or remain blank
3. Check AC Power Source
- Plug into a known good outlet
- Verify outlet functionality
- Inspect power cord connection at rear inlet
4. Swap Power Cord
- Replace with a known good hospital-grade power cord
- Reattempt power on
5. Remove All Attached Modules
- Detach all pump modules
- Power on the PC unit alone
- Observe if error persists or clears
6. Reattach Modules One at a Time (If Error Clears)
- Reconnect modules individually
- Power cycle between each addition
- Identify if error returns with a specific module
7. Inspect Battery Condition
- Check for swelling, leakage, or aging battery
- Test with a known good battery if available
8. Attempt Power-On Using AC Only
- Operate unit with battery removed if allowed
- Determine if error changes
9. Inspect for Physical Damage or Fluid Ingress
- Check connectors and housing for contamination
- Look for corrosion, discoloration, or burn smell
10. Power Cycle the System
- Turn off the device
- Wait 10–15 seconds
- Restart and observe behavior
If the Problem Persists
If Error 120.4340 continues after external troubleshooting:
- External power, cord, battery, and modules have been ruled out
- Internal 5V supply overvoltage condition remains
- Remove device from service
- Label Out of Service
- Send for repair or bench evaluation
Clinical Use Tip
Never troubleshoot a power-related error on an active patient. Always transfer the patient to a backup device before continuing diagnostics.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Alaris PC unit displaying Error 120.4340 and would not power or initialize."
Cause
What was observed during troubleshooting.
Example:
"Internal 5V power rail overvoltage suspected after verifying AC source, replacing cord, isolating modules, and testing battery."
Resolution
What action was taken.
Example:
"Removed PC unit from service, labeled out of service, and sent for repair."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Power supply errors in modular systems should always be approached from the outside in. Once external causes are ruled out, escalation is the safest and most efficient path forward.
That is successful troubleshooting.