Siemens Essenza 1.5T: frequency calibration fault at scan start after software restore
What happened
After a software reinstall with an old master backup restored, the system booted without errors, but every scan attempt stopped with a frequency calibration fault and no image.
What was checked
- Verified the fault appeared only at scan start while the system itself booted clean — pointing to calibration data rather than RF hardware.
- Tried retuning and manual frequency adjustment; per the case, these alone were not enough.
- Concluded the resonance frequency had drifted since the backup was taken and ran the RF Characterization calibration from the service documentation.
Cause
The engineers found that the main field — and with it the resonance frequency — had drifted since the old backup was made, so the restored calibration data no longer matched the actual system and the scanner flagged a frequency calibration fault.
What was done
The RF Characterization procedure from the manufacturer's service documentation, performed by authorised personnel, was run; per the case, the error cleared and images returned, with final verification on patients still planned before routine clinical use.
Safety
The superconducting magnet is always energised and stores large amounts of energy — keep magnet and cryogen safety rules in force during any work on the RF chain, and complete the manufacturer's QA verification before returning the scanner to clinical use.
Lesson: An old backup carries old calibration data — after any software restore, expect to re-run frequency/RF calibration, because the field keeps drifting in the meantime.
Covered in the course: MRI 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.