CONMED System 2450 / 5000 Series

Asset Type

Electrosurgical Unit (ESU)

Manufacturer

CONMED

Model

System 2450 / 5000 Series

What This Guide Helps With

This guide helps troubleshoot Err 118 on a CONMED System 2450 / 5000 Series electrosurgical unit. Err 118 indicates the ESU is detecting the internal 5.0 V supply as too high, which may prevent normal startup or safe operation.

A voltage-related fault can affect internal logic, monitoring circuits, controls, and generator safety functions. Treat this as a device fault until the unit has been evaluated and verified safe.

Step-by-Step Troubleshooting

Ensure Patient Safety First

• Remove the ESU from patient use if Err 118 is displayed or if the generator does not operate normally.
• Stop use of the ESU.
• Have clinical staff switch to another electrosurgical generator if the procedure requires electrosurgery.
• Do not continue using the unit with an unresolved voltage-related error.
• Label the unit appropriately if the error cannot be cleared.

Expected outcome: Patient care continues with a working ESU.

Why it matters: A low-voltage supply fault may affect control logic, monitoring circuits, user controls, alarms, and safe generator operation.

Verify the Reported Error and Behavior

• Power the unit on and confirm the exact displayed error is Err 118.
• Note whether the error appears immediately at startup, during POST, intermittently, or after the unit warms up.
• Confirm whether the ESU completes startup or remains locked out.
• Listen for abnormal sounds and check for unusual heat or smell.

Expected outcome: Err 118 is reproducible or clearly confirmed.

Why it matters: This confirms a true system-reported voltage fault instead of a user-reported issue with unclear symptoms.

Translate the Error Into a Real-World Condition

Err 118 indicates the ESU is detecting the internal 5.0 V supply as too high.

In practical terms, this means the generator’s low-voltage power system or Controller voltage monitoring circuit is reporting an over-voltage condition.

• Low-voltage power supply output above acceptable limits
• Controller assembly sensing or ADC reference issue
• Incorrect voltage reference on the Controller
• Internal power regulation failure

Expected outcome: The issue is treated as a power/control fault, not an accessory or output cable problem.

Check the Power Source First

• Verify the ESU is connected to a known-good hospital-grade outlet.
• Check that the power cord is fully seated and undamaged.
• Inspect the plug, cord, strain relief, and inlet for damage, looseness, burning, or contamination.
• If safe and allowed by facility policy, test the unit on another known-good outlet.

Expected outcome: The unit receives stable AC input power and the error behavior does not change due to the outlet or cord.

Why it matters: Basic power issues should be ruled out before suspecting internal assemblies.

Inspect the Exterior Condition

• Check the ESU for signs of fluid intrusion, impact damage, cracked housing, missing screws, damaged controls, or contamination.
• Inspect the display and front panel for abnormal behavior.
• Confirm the unit has not recently been dropped, cleaned excessively, or exposed to liquid.

Expected outcome: No external condition explains the fault.

Why it matters: Fluid or impact damage can create internal power regulation and controller issues.

Cycle Power and Recheck

• Turn the ESU off.
• Disconnect power for a short period.
• Reconnect power and restart the unit.
• Confirm whether Err 118 returns.

Expected outcome: If the error was temporary, the unit starts normally. If Err 118 returns, continue troubleshooting.

Why it matters: A repeated Err 118 suggests an active voltage fault rather than a one-time startup glitch.

Remove Accessories From the Equation

• Disconnect handpieces, footswitches, patient return electrode cables, bipolar accessories, and any external accessories.
• Power the unit on with only the power cord connected.
• Observe whether Err 118 still appears.

Expected outcome: Err 118 remains present if the problem is internal to the ESU.

Why it matters: Although Err 118 points to an internal voltage condition, removing accessories prevents chasing a secondary or unrelated issue.

Check for Configuration or Use-Related Clues

• Ask staff what happened before the error appeared.
• Determine whether the error occurred after cleaning, transport, storage, a power event, or a previous repair.
• Confirm whether the error is constant or intermittent.

Expected outcome: Any pattern is documented for repair evaluation.

Why it matters: Intermittent voltage faults may be related to heat, vibration, damaged wiring, or unstable internal power supply behavior.

Bench Evaluate the Low-Voltage Supply

• Remove the unit from clinical use and evaluate it on the bench.
• Check the output of the low-voltage power supply according to service procedure and facility safety practices.
• Verify whether the 5.0 V output is above the acceptable range.

Expected outcome: The low-voltage supply output is either within limits or confirmed too high.

Why it matters: Err 118 specifically points toward the 5.0 V supply being detected above range.

Verify Controller Reference Voltage

• If the low-voltage power supply output appears within limits, verify the ADC reference voltages on the Controller.
• Confirm the Controller reference voltage is approximately 2.5 V where applicable.
• Look for unstable, incorrect, or missing reference voltage behavior.

Expected outcome: ADC reference voltage is stable and correct.

Why it matters: If the 5.0 V supply is actually normal but the Controller reference is incorrect, the Controller may falsely interpret the voltage as too high.

Isolate Power Supply Versus Controller

• If the 5.0 V supply output is out of limits, suspect the low-voltage power supply.
• If the 5.0 V supply output is within limits but Err 118 remains, suspect the Controller assembly or voltage sensing/reference circuit.
• Do not return the ESU to service unless the error is cleared and the device passes required testing.

Expected outcome: The fault is narrowed to either the low-voltage power supply or Controller assembly.

Why it matters: Replacing parts without confirming the supply condition can lead to unnecessary repair cost and repeat failure.

Stop When Resolved

• Confirm Err 118 no longer appears.
• Verify the ESU completes startup normally.
• Perform required operational and safety testing per facility procedure.
• Confirm the unit is safe for clinical use.
• Return the device to service only after successful testing.

Expected outcome: The ESU powers on normally, no Err 118 is displayed, and required checks pass.

If the Problem Persists

If Err 118 remains after external power, accessories, physical condition, and basic bench checks are ruled out, the fault strongly indicates an internal power supply or Controller-related failure.

The device should be removed from service, labeled Out of Service, and sent for repair or deeper bench evaluation.

Likely corrective actions include replacing the low-voltage power supply if the 5.0 V output is out of limits, or replacing the Controller assembly if the supply voltage is within limits but the error persists.

Knowing when to stop is proper troubleshooting. A voltage regulation fault inside an ESU should not be treated as a user-level problem.

Clinical Use Tip

Never troubleshoot an ESU on an active patient. If Err 118 appears during setup or clinical use, move the patient or procedure to a known-good backup ESU first, then troubleshoot the affected generator away from patient 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 reported with Err 118 5.0 volt too high. Unit would not complete normal operation and was removed from clinical use."

Cause

What was observed during troubleshooting.

Example:
"Confirmed Err 118 during startup/bench check. External power source, power cord, accessories, and visible physical condition checked. Error indicates internal 5.0 V supply over-limit condition or Controller voltage sensing/reference issue."

Resolution

What action was taken.

Example:
"Removed unit from service. Bench evaluation performed. Low-voltage power supply output and Controller ADC reference voltage require verification. If 5.0 V supply is out of limits, replace low-voltage power supply. If supply is within limits and fault persists, replace Controller assembly. Final return to service requires successful startup, operational verification, and required safety testing."

Helpful Details to Include (If Known)

• Alarm behavior
• Accessories swapped
• Power behavior
• Environmental factors
• Indicator lights
• Final device status

Final Thought

Err 118 should be handled as a real internal voltage-related fault until proven otherwise. Start with patient safety and simple external checks, then move logically toward power supply and Controller isolation. Do not keep an ESU in service with an unresolved voltage error. Good documentation helps show what was ruled out, what was confirmed, and why escalation or repair was appropriate.

That is successful troubleshooting.