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 136 on the CONMED System 2450 / 5000 Series Electrosurgical Unit when the A.R.M.™ circuit voltage drops below 0.4 V. This condition may indicate a return electrode monitoring signal issue, output assembly problem, signal path failure, or controller sensing failure.

Because A.R.M.™ monitoring is related to patient return electrode safety, this error should be treated as a patient safety concern until the device has been evaluated and verified safe for use.

Step-by-Step Troubleshooting

Ensure Patient Safety First

• Remove the ESU from patient use if Err 136 appears during setup, startup, activation, or clinical use.
• Have clinical staff switch to another approved electrosurgical generator if electrosurgery is still needed.
• Do not attempt repeated activation on a patient while the error is unresolved.
• Label the unit for Clinical Engineering evaluation if the error cannot be cleared safely.

Verify the Reported Error and Behavior

• Power the unit on in a safe non-patient-use setting.
• Confirm the exact displayed error is Err 136.
• Note whether the error appears during startup, during POST, when a return electrode is connected, during activation, or intermittently during movement.
• Check whether the unit allows operation or locks out activation.

Understand What the Error Means

• Err 136 means the A.R.M.™ circuit voltage dropped below 0.4 V.
• Treat this as an abnormally low monitoring feedback signal, not just a nuisance error.
• Do not clear and return the ESU to service unless the fault is corrected and the unit passes required functional testing.

Check Power Source and Basic Setup

• Verify the ESU is connected to a known-good hospital-grade outlet.
• Inspect the power cord for damage, loose fit, bent blades, or signs of overheating.
• Power-cycle the unit once using a normal shutdown and restart process.
• Avoid repeated resets if Err 136 returns.

Check External Accessories and Return Electrode Setup

• Remove connected pencils, footswitches, patient return electrodes, adapters, and active cables.
• Inspect the return electrode connection area for bent pins, contamination, fluid intrusion, debris, or damage.
• Reconnect only known-good accessories if testing requires them.
• Use a known-good return electrode or appropriate test setup if available.

Inspect the Output Connector Area

• Inspect the patient return electrode connector and output jack area.
• Look for damaged contacts, loose connector fit, broken housing, cleaning-fluid intrusion, burn marks, contamination, or debris inside the connector.
• Clean and dry the external connector area only if allowed by facility procedure and manufacturer guidance.

Check for Intermittent Behavior

• With the unit safely on the bench, observe whether Err 136 appears when accessories are connected or disconnected.
• Watch for changes when the return electrode connector area is lightly handled or when the unit is restarted.
• Do not strike, shake, or stress the unit.
• If the fault changes with movement, suspect a loose connection, damaged connector area, output assembly connection issue, or internal harness problem.

Isolate External Setup From Device Failure

• Test using a known-good outlet.
• Use a known-good power cord if the cord is removable.
• Use a known-good return electrode or approved test accessory.
• Remove unnecessary accessories from the generator.
• Confirm the connector area is clean, dry, and undamaged.
• If Err 136 remains after these checks, the problem is likely internal to the ESU.

Bench Evaluate the A.R.M.™ Signal Path

• During bench evaluation, verify the VARM signal entering the Controller assembly according to approved service procedures.
• If VARM entering the Controller assembly is faulty, suspect the Output assembly or signal path feeding the controller.
• If VARM entering the Controller assembly appears correct, suspect the Controller assembly.
• Do not replace parts blindly without first isolating whether the fault is coming from the output side or the controller sensing side.

Determine Corrective Action

• If the VARM signal entering the Controller assembly is faulty, repair or replace the Output assembly as appropriate.
• If the VARM signal appears correct entering the Controller assembly, replace the Controller assembly as appropriate.
• Verify all related cabling and connections are properly seated before final testing.
• After repair, perform required functional testing, ESU performance verification, and electrical safety testing before returning the unit to service.

Stop When Resolved

• Confirm the unit powers on without Err 136.
• Confirm return electrode monitoring behavior is acceptable.
• Confirm ESU output testing is acceptable per facility procedure.
• Return the device to service only after all required checks pass.

If the Problem Persists

If Err 136 continues after power, accessories, return electrode setup, connector condition, and other external causes have been ruled out, the condition strongly suggests an internal A.R.M.™ circuit, Output assembly, signal path, or Controller assembly failure.

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

Do not keep cycling power or returning the ESU to clinical use with Err 136 present.

Clinical Use Tip

Never troubleshoot an ESU with an active A.R.M.™ circuit error on a patient. Move the patient or procedure to a known-good backup ESU first, then evaluate the affected generator on the bench. A return electrode monitoring-related fault should always be treated as a patient safety concern until proven otherwise.

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 136 A.R.M.™ circuit voltage low error and was removed from service."

Cause

What was observed during troubleshooting.

Example:
"Err 136 confirmed during bench evaluation. External power, accessories, return electrode setup, and connector condition were checked. Fault persisted, indicating likely internal A.R.M.™ signal path, Output assembly, or Controller assembly failure."

Resolution

What action was taken.

Example:
"Removed unit from service and labeled Out of Service. Verified VARM signal path per service procedure. Unit requires Output assembly or Controller assembly repair based on VARM findings, followed by functional testing, ESU performance verification, and safety testing 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 136 should be approached as a safety-related monitoring circuit fault, not just a reset-and-return issue. Start with patient safety and simple external checks, then logically isolate the return electrode setup, connector condition, A.R.M.™ signal path, Output assembly, and Controller assembly. Clear CCR documentation helps the next technician understand what was ruled out and why the device was escalated or returned to service.

That is successful troubleshooting.