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What This Guide Helps With
This guide helps troubleshoot CONMED System 2450 / 5000 Series Error Err 387, where POST detects that the HVDC supply intended for the 140V startup check is too high. This can prevent the electrosurgical generator from completing startup self-test, lock out activation, and indicate an internal high-voltage power supply regulation or controller feedback problem.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Stop using the ESU if Err 387 appears during setup, startup, or use.
- Notify clinical staff that the generator failed its startup self-test.
- Provide a backup electrosurgical generator if the procedure requires electrosurgery.
- Do not keep attempting activation on a unit with an unresolved high-voltage supply fault.
Verify the Reported Error and Behavior
- Confirm the exact displayed error is Err 387.
- Power the unit on and observe the startup POST sequence.
- Note whether the error appears every time or only intermittently.
- Document whether the unit completes startup, locks out operation, alarms, or prevents activation.
- Ask staff whether the issue occurred at startup, during setup, after the unit was moved, or after a power event.
Power Cycle the System
- Turn the ESU off.
- Disconnect it from AC power for at least 30 seconds.
- Reconnect the unit to a known-good hospital-grade outlet.
- Power the unit back on and observe whether POST completes normally.
- If Err 387 clears, complete required safety and performance checks before returning the unit to service.
Check the Power Source
- Plug the ESU directly into a known-good wall outlet.
- Avoid questionable extension cords, power strips, or temporary shared power sources.
- Check that the outlet is not loose, damaged, or intermittently losing power.
- Inspect the power cord and plug for damage, heat marks, arcing, bent blades, or looseness.
Remove External Accessories
- Disconnect patient accessories before retesting the generator.
- Remove active pencils, footswitches, return electrode cables, adapters, and active cords.
- Restart the ESU with only AC power connected.
- Confirm whether Err 387 remains with accessories removed.
Inspect External Condition
- Inspect the case, display, controls, rear panel, power inlet, and visible connectors.
- Look for fluid intrusion, impact damage, missing hardware, contamination, or a burning smell.
- Do not open the unit in the clinical area.
- If damage or contamination is found, remove the device from service for bench evaluation.
Confirm the Fault Is Internal to the Generator
- If Err 387 remains after power cycling, accessory removal, and known-good AC power testing, treat the fault as internal.
- Record whether the fault occurs immediately, after a delay, or during a specific part of POST.
- Do not repeatedly power cycle the generator beyond reasonable confirmation.
- Remove the ESU from clinical use and send it for qualified bench evaluation.
Bench Evaluation Only
- Configure the system for test mode only if performed by qualified service personnel using approved procedures.
- Verify HVPS control signals from the controller while the unit is being commanded.
- Verify HVPS operation during the failed POST condition.
- Inspect internal cabling only to the level allowed by facility policy, training, and service documentation.
- Use test findings to determine whether the controller is commanding incorrectly, the HVPS is regulating incorrectly, or the feedback path is failing.
Determine the Repair Path
- Suspect the HVPS or Controller assembly based on bench test findings.
- Repair or replace the HVPS if it is not regulating correctly.
- Replace the Controller assembly if control signals, command logic, or monitoring feedback are incorrect.
- Perform required post-repair electrical safety, functional, and ESU performance testing before returning the unit to service.
If the Problem Persists
If Err 387 continues after power cycling, removing external accessories, checking the power cord, and testing from a known-good AC outlet, the common external causes have been ruled out.
A persistent Err 387 strongly indicates an internal generator issue involving HVPS regulation, controller command or feedback, or related internal cabling.
The device should be removed from service, labeled Out of Service, and sent for repair or bench evaluation.
Clinical Use Tip
Never troubleshoot an ESU with Err 387 on an active patient or during an active procedure. Move the patient or procedure to a backup generator first, then evaluate the failed unit away from clinical use.
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 387 during startup and failed POST. Unit was not available for clinical use."
Cause
What was observed during troubleshooting.
Example:
"Err 387 repeated during startup after power cycle and known-good outlet check. Accessories were removed and fault remained. External causes ruled out. Fault indicates likely internal HVPS regulation, controller command, or feedback issue."
Resolution
What action was taken.
Example:
"Removed ESU from service and labeled Out of Service. Sent for bench evaluation. Test mode verification of HVPS control signals and HVPS operation required. Repair path includes Controller assembly replacement or HVPS repair/replacement based on bench findings."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Err 387 should be treated as a serious ESU startup fault because the generator is reporting that the 140V HVDC supply is too high during POST. Start with patient safety, confirm the exact error, rule out simple external causes, then escalate when the fault remains. Clear documentation shows that Clinical Engineering isolated the problem logically and removed the device from service when internal failure was likely.
That is successful troubleshooting.