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What This Guide Helps With
This guide helps troubleshoot Err 385 on the CONMED System 2450 / 5000 Series electrosurgical unit. Err 385 indicates that the unit failed the power-on self-test because the HVDC 30V supply check was too high.
This condition may point to an HVPS regulation problem, incorrect HVPS control signal, controller assembly fault, or an internal connection issue. Because this fault involves the high-voltage power supply system used for RF output control, the ESU should not be used clinically until the issue is evaluated and resolved.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Remove the ESU from patient use if Err 385 is present.
- Do not attempt to use the generator during a procedure while this error is active.
- Have clinical staff switch to a known-good ESU if electrosurgery is needed.
- Label the affected unit for Clinical Engineering evaluation.
- Do not troubleshoot the generator on an active patient or during an active case.
Verify the Reported Error and Behavior
- Power the unit on in a safe non-patient-care setting.
- Confirm the exact displayed error is Err 385.
- Note whether the error appears immediately at startup, during POST, intermittently, or after repeated power cycles.
- Check whether the unit completes startup or stops before normal operation.
- Listen for abnormal sounds and check for unusual odor, heat, display problems, or other startup issues.
Check the Power Source First
- Confirm the ESU is plugged into a known-good hospital-grade outlet.
- Inspect the power cord for cuts, loose plug blades, damaged strain relief, or signs of overheating.
- Do not test from a questionable power strip, damaged outlet, or adapter.
- Power cycle the ESU using a verified outlet and see whether Err 385 returns.
Perform a Basic External Inspection
- Inspect the housing for impact damage, missing hardware, fluid intrusion, or cracked panels.
- Check the front panel, display, controls, accessory ports, and output connectors for damage or contamination.
- Remove patient accessories unless they are required for the approved test procedure.
- Confirm there is no obvious external condition contributing to the startup failure.
Power Cycle and Recheck
- Turn the ESU off.
- Disconnect the unit from AC power.
- Wait briefly for the system to fully reset.
- Reconnect power and restart the unit.
- Observe whether Err 385 clears or repeats during POST.
- If the error clears, perform required operational and safety checks before returning the unit to service.
- If the error repeats, keep the unit out of service and continue bench evaluation.
Configure the Unit for Test Mode
- Set the ESU up for test mode according to approved service procedures.
- Use proper ESU test equipment and follow facility safety policy.
- Do not perform internal testing unless you are qualified and authorized to service the generator.
- Keep the unit out of clinical use during testing.
Verify HVPS Control Signals From the Controller
- In test mode, verify the HVPS control signals from the controller while activated as required by the service procedure.
- Check for missing, incorrect, unstable, or abnormal control signals.
- Inspect accessible internal cabling and connectors between the controller and HVPS for looseness, damage, or poor seating.
- If control signals are abnormal, suspect the Controller assembly or control-side connection path.
- If control signals are correct, continue checking HVPS operation.
Verify HVPS Operation
- Evaluate HVPS behavior according to the approved service procedure.
- Confirm whether the HVPS output is regulating correctly during the 30V POST-related check.
- Look for output that is too high, unstable, or not responding correctly to controller commands.
- If control signals are correct but the HVPS output remains too high, suspect the HVPS.
Isolate the Failure Path
- Suspect a controller-related issue if HVPS control signals are incorrect.
- Suspect an HVPS-related issue if control signals appear correct but HVPS output remains too high.
- Suspect a cabling or connection issue if the error changes after connectors are inspected or reseated.
- Repair or replace the Controller assembly, HVPS, or related internal cabling as indicated by testing.
Verify Repair Before Returning to Service
- Confirm the ESU completes POST without Err 385.
- Perform required ESU performance testing according to facility policy.
- Verify output and safety checks pass before returning the unit to clinical use.
- Document the final device status clearly in the work order.
If the Problem Persists
If Err 385 continues after checking the power source, power cycling the unit, inspecting the exterior, configuring test mode, checking HVPS control signals, verifying HVPS operation, and checking related internal cabling, external and common causes have been ruled out.
A persistent Err 385 strongly indicates an internal failure involving the HVPS, Controller assembly, or related internal control path.
The device should be removed from service, labeled Out of Service, and sent for repair or bench evaluation. Do not return the ESU to clinical use until repair is completed and the unit passes required performance and safety testing.
Clinical Use Tip
Never troubleshoot an ESU with an active power supply POST fault on an active patient. Move the patient to a backup device first. An unresolved HVDC fault can affect RF output control and should be treated as a patient safety concern.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"CONMED System 2450 / 5000 Series ESU displayed Err 385 during startup and failed to complete normal POST."
Cause
What was observed during troubleshooting.
Example:
"Confirmed Err 385 during power-on self-test. External power source and basic external condition checked. Fault indicates HVDC 30V POST level too high, with likely HVPS regulation issue, controller signal issue, or internal connection path fault."
Resolution
What action was taken.
Example:
"Power cycled unit and retested. Removed ESU from service for bench evaluation. Verified need to check HVPS control signals and HVPS operation. Unit remained out of service pending repair of Controller assembly, HVPS, or related internal cabling as indicated."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Err 385 should be treated as a real ESU power supply control fault until proven otherwise. Start with patient safety, confirm the exact displayed error, rule out simple external causes, then isolate whether the failure is related to controller command signals, HVPS regulation, or internal connections. Clear escalation and CCR documentation protect patients, staff, and the repair process.
That is successful troubleshooting.