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What This Guide Helps With
This guide helps troubleshoot COLL IRIS POTENTIOMETER ERROR - PRESS ANY KEY on the GE Healthcare OEC 9900 Series C-Arm. This error indicates that the system is not receiving valid collimator iris position feedback. When this feedback is missing, incorrect, fixed, or unreliable, generator functions including X-rays may be disabled because the system cannot confirm proper collimator iris position.
Because collimation affects image field size and radiation exposure area, this error should be treated as a safety-related imaging control issue, not just a nuisance message.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Remove the C-Arm from patient use if X-rays are disabled or collimator operation is questionable.
- Do not troubleshoot this error while the device is actively being used for a patient procedure.
- If imaging is needed immediately, have clinical staff switch to another C-Arm or approved imaging method.
- Do not attempt repeated X-ray operation while collimator iris position feedback is unreliable.
Verify the Reported Error and Behavior
- Confirm the display shows COLL IRIS POTENTIOMETER ERROR - PRESS ANY KEY.
- Note whether the error appears during startup, during collimator adjustment, or intermittently during use.
- Confirm whether generator functions or X-ray operation are disabled while the error is active.
- Press any C-Arm key and observe whether the message clears or immediately returns.
Check for Obvious External or Mechanical Problems
- Inspect the collimator area for signs of impact, loose covers, contamination, or visible damage.
- Look for anything that may restrict iris movement.
- Check whether the iris mechanism appears stuck, restricted, or physically damaged.
- Do not force the iris mechanism.
Check Collimator Iris Movement
- If the system allows it, attempt to adjust the collimator iris using normal controls.
- Observe whether the iris moves smoothly, moves only partially, or does not move at all.
- Listen for abnormal motor noise, clicking, grinding, or stalled movement.
- If movement is abnormal, remove the device from service if the issue cannot be corrected through approved external checks.
Inspect Potentiometer Wiring and Connector Seating
- Inspect accessible wiring related to the collimator iris potentiometer.
- Check for loose connector seating, bent pins, damaged insulation, pinched wiring, corrosion, contamination, or signs of prior service strain.
- Reseat accessible connectors only if allowed by facility procedure.
- Do not perform internal disassembly beyond approved service access.
Check Whether the COLL_IRIS_POSN Signal Changes
- Check the COLL_IRIS_POSN signal on the Fluoro Functions PCB according to site procedure and service-level access.
- Move the iris through its range if possible.
- Confirm whether the signal changes smoothly as the iris moves.
- If the signal is missing, fixed, erratic, or out of expected range, suspect the iris potentiometer, wiring, connector path, iris mechanics, or Fluoro Functions PCB input circuit.
Isolate the Likely Feedback Path Cause
- If the iris moves mechanically but the signal does not change, focus on the potentiometer and wiring.
- If the signal changes at the potentiometer but not at the Fluoro Functions PCB, suspect a harness or connector issue.
- If the signal reaches the Fluoro Functions PCB but the system still reports the error, suspect board-level input processing or related control circuitry.
- Avoid jumping directly to board replacement until simple mechanical, connector, and wiring causes have been checked.
Clear the Error and Recheck Operation
- After correcting any external, wiring, or mechanical issue, power cycle the system if required.
- Confirm whether the error returns.
- Adjust the iris through its range and verify normal response.
- Confirm generator functions and X-ray operation are restored only after required operational and safety checks are completed.
If the Problem Persists
If the error continues after checking iris movement, visible mechanical condition, potentiometer wiring, connector seating, and COLL_IRIS_POSN signal behavior, external and common causes have been ruled out.
A persistent COLL IRIS POTENTIOMETER ERROR - PRESS ANY KEY may indicate a failed collimator iris potentiometer, wiring harness fault, Fluoro Functions PCB issue, or internal collimator control failure.
The device should be removed from service, labeled Out of Service, and sent for repair or bench evaluation.
Clinical Use Tip
Never troubleshoot this error on an active patient. Move the patient to a backup device or approved alternate imaging method first. A C-Arm with unresolved collimator feedback problems may disable X-rays or create uncertainty about field size control.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"GE Healthcare OEC 9900 Series C-Arm displayed COLL IRIS POTENTIOMETER ERROR - PRESS ANY KEY. User reported X-rays or generator functions were disabled and collimator iris operation could not be confirmed."
Cause
What was observed during troubleshooting.
Example:
"Collimator iris position feedback fault observed. COLL_IRIS_POSN signal did not change normally with iris movement, indicating possible iris potentiometer, wiring, connector, mechanical iris, or Fluoro Functions PCB feedback issue."
Resolution
What action was taken.
Example:
"Removed C-Arm from service. Inspected collimator iris mechanics, potentiometer wiring, connector seating, and feedback signal path. Error persisted after external checks. Unit labeled Out of Service and escalated for repair or bench evaluation."
Helpful Details to Include (If Known)
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
The COLL IRIS POTENTIOMETER ERROR should be handled as a collimator position feedback failure. Start with patient safety, confirm the exact message, check external and mechanical causes first, inspect wiring and connector seating, then isolate whether the issue is potentiometer, harness, or board-related. If the feedback signal cannot be verified, removing the C-Arm from service is the correct decision.
That is successful troubleshooting.