On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
This guide helps troubleshoot Err 374 on a CONMED System 2450 / 5000 Series electrosurgical unit. Err 374 indicates the damping circuit failed POST because damping is detected as stuck on. This may prevent normal RF output operation and should be treated as an internal RF control-related fault until evaluated.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Remove the ESU from patient use if Err 374 appears during startup, setup, or clinical use.
- Stop use of the generator.
- Notify clinical staff that the ESU has failed startup or self-test.
- Provide a known working backup ESU if electrosurgery is needed.
- Do not continue using the generator if the error repeats.
2. Verify the Reported Error and Behavior
- Power the unit on in a safe non-patient-care setting.
- Confirm the displayed error is Err 374.
- Document whether the error appears during POST, immediately after power-up, or during activation testing.
- Confirm whether the unit locks out normal operation.
- Listen for abnormal tones and observe any unusual display behavior.
3. Cycle Power and Recheck
- Turn the ESU off.
- Disconnect it from AC power briefly.
- Reconnect power and restart the unit.
- Observe whether Err 374 returns during POST.
- If the error clears and does not return, perform functional testing and follow facility policy before returning the unit to service.
4. Check Power Source and External Setup
- Verify the ESU is connected to a proper hospital-grade outlet.
- Inspect the power cord for damage, loose fit, bent blades, heat marks, or contamination.
- Confirm the unit is not connected through a questionable power strip or damaged outlet.
- Disconnect external accessories during startup if appropriate for the check.
- Verify no handpiece, footswitch, return electrode cable, or accessory is creating confusion during startup.
5. Inspect the Unit Externally
- Check the ESU housing for impact damage, fluid intrusion, missing screws, cracked panels, or signs of overheating.
- Inspect output ports for damage, debris, bent contacts, or contamination.
- Look for burn marks, abnormal odor, rattling, or evidence that the unit was dropped.
- Document any visible damage before repair evaluation.
6. Verify Internal Cable Connections During Bench Evaluation
- Remove the unit from clinical use and perform bench evaluation according to facility policy.
- With power disconnected, inspect accessible internal cable connections only if qualified and permitted.
- Verify internal cables related to the RF Amplifier and Controller assemblies are fully seated and not damaged.
- Look for loose connectors, pinched wiring, corrosion, or signs of overheating.
- Do not continue into board-level troubleshooting unless your department is authorized and equipped for that level of service.
7. Configure for Test Mode if Available and Authorized
- Configure the ESU for test mode only if trained and authorized.
- Attempt to reproduce the fault under controlled bench conditions.
- Monitor whether the fault appears during POST or during activation testing.
- Use approved test equipment and service procedures.
8. Check Damping Control Behavior During Spray or Standard Coag
- Using proper test equipment and service procedures, check the RFDAMP_DR signal during Spray or Standard Coag activation.
- Verify whether the damping drive signal changes state correctly during RF activation.
- Err 374 indicates the damping circuit is detected as stuck on during POST.
- If the damping control behavior remains abnormal, suspect the RF Amplifier damping circuitry, controller drive signal, or related internal connections.
9. Isolate the Likely Failure Area
- If cabling is secure and the damping signal remains abnormal, suspect the RF Amplifier assembly.
- Pay particular attention to the damping circuitry on the RF Amplifier assembly.
- Q1 failure may be involved.
- If RF Amplifier repair or replacement does not resolve the fault, evaluate the Controller assembly as the next likely source.
- Do not assume this fault is caused by a handpiece, patient return electrode, footswitch, or basic user setup issue.
10. Stop When Resolved
- If reseating an internal cable or correcting a simple connection issue resolves the error, run the ESU through startup successfully.
- Perform required functional testing.
- Verify proper output operation using approved ESU test equipment.
- Complete electrical safety testing if required by facility policy.
- Return the device to service only after it passes all required checks.
If the Problem Persists
If Err 374 continues after power, external setup, visible damage, internal cable seating, and controlled bench checks have been completed, the common external causes have been ruled out.
A persistent Err 374 strongly indicates an internal damping circuit, RF Amplifier, or Controller assembly failure.
The device should be removed from service, labeled Out of Service, and sent for repair or bench evaluation by qualified service personnel or the manufacturer.
Do not return an ESU to clinical use with an unresolved RF control or POST failure.
Clinical Use Tip
Never troubleshoot an ESU with an unresolved POST error during active patient use. Move the patient to a backup device first, then evaluate the failed unit on the bench in a controlled service setting.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"CONMED System 2450 / 5000 Series ESU reported Err 374 during startup. Error indicates damping circuit failed POST with damping detected stuck on. Unit removed from patient use."
Cause
What was observed during troubleshooting.
Example:
"Err 374 confirmed during POST. External power and setup checked. No accessory-related cause identified. Internal cable connections require verification. Persistent fault indicates likely RF Amplifier damping circuit failure, possible Q1 failure, or Controller assembly issue."
Resolution
What action was taken.
Example:
"Removed ESU from service and labeled Out of Service. Verified reported Err 374 condition. Checked external power, power cord, output ports, and visible condition. Unit requires bench evaluation of internal cabling, RFDAMP_DR signal, RF Amplifier assembly, and Controller assembly before return to service."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Err 374 should be treated as an internal RF control-related fault until proven otherwise. Start with patient safety, confirm the exact error, rule out simple external and connection issues, then escalate appropriately. Clear documentation matters because damping circuit failures affect confidence in safe ESU output control.
That is successful troubleshooting.