Siemens Artis zee: intermittent position errors force work stops
What happened
Periodic position errors interrupted the work, and the engineers had to press stop before continuing. The reference voltage shown by the service diagnostics (about 9.82 V, as reported in the case) did not match the multimeter reading taken directly on the potentiometer (about 9.96 V).
What was checked
- Reviewed the error history through the manufacturer's service diagnostics to separate a potentiometer fault from a calibration problem.
- Compared the reference voltage reported by the service diagnostics with a direct multimeter measurement on the potentiometer; the mismatch (about 9.82 V vs about 9.96 V, as reported in the case) pointed to the potentiometer itself rather than calibration alone.
Cause
Probable in this case: a worn or drifting position potentiometer giving intermittent out-of-spec feedback — the engineers noted these potentiometers are considered a weak point on this platform.
The cause is probable and was not fully confirmed.
What was done
The engineers cycled the potentiometer from stop to stop a few times and ran the linearity and end-position calibration — a procedure from the manufacturer's service documentation, done by authorised personnel. Since the errors tended to recur, a replacement potentiometer was ordered; the outcome in this case was considered probable.
Safety
Work on position sensors of a counterbalanced C-arm involves stored mechanical energy and possible unexpected motion, and the room is a radiation area: isolate as required by the service documentation, keep hands and the patient side clear of moving parts, and verify motion, stops and interlocks before returning the system to clinical use.
Lesson: When the service diagnostics and a multimeter disagree on a position sensor's reference value, suspect the potentiometer itself: recalibration only buys time, so plan the replacement before nuisance stops turn into a case-stopping failure.
Covered in the course: Angiography and C-arm Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.