Philips Intera 1.5: no RF signal, resonance frequency not found during scan
What happened
During a patient scan the system reported it could not determine the resonance frequency and gave no signal at all. The standard tests (bdas, gradients, maxkv, pmu) all passed and f0 was determined in the test; after running the tests, the error message changed its wording. Reported in the case, one machine.
What was checked
- Checked for metal objects near the coil.
- Identified the RF amplifier type (S23 in this case).
- Ran the two coil peak measurement tests.
- Considered the VSWR test: the engineers expected the pickup coil trip level and VSWR to fail if the fault were in the RF chain.
Cause
A software fault: the tuned-hardware configuration file (hw_tuned.dat) was corrupted or contained incorrect data, so the RF tuning information did not match the system even though the hardware passed every test. The engineers found this in this one case.
What was done
The engineers restored hw_tuned.dat from a known-good backup copy, and the fault cleared completely. Work with system configuration files should follow the manufacturer's service documentation and be done by authorised personnel.
Safety
Before working near the bore, check all tools for ferromagnetic parts and respect the magnetic field, and after any intervention in the RF chain run the electrical safety tests before returning the scanner to patient use.
Lesson: A no-signal RF fault is not always hardware: when every hardware test passes, check the integrity of the system's tuning and configuration files before ordering parts.
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.