Toshiba Excelart: start-up error in the gradient cabinet, reset does not always take
What happened
At power-up the scanner reports a gradient-related error. It can be cleared with the reset control on the status page, but in this case not always on the first attempt.
What was checked
- Identify the faulty gradient axis from the digit indicators lit on the upper board of the gradient cabinet.
- Localise the faulty sub-unit using the LED indicators on the modules.
- Continuity-check the fuses inside the affected unit.
- Watch the live status line on the console computer for the current fault message.
- Check the chiller temperature (reported around 21 °C in this case) and confirm the air dryer works, since humidity at the gradients affects reliability.
Cause
In this case the suspected cause was breakdown of tantalum capacitors, 20 µF / 15 V (the engineers reported about eight in a row) in the gradient unit, with the associated 2 A fuse blown. This was a probable cause, not a confirmed one from the case alone.
The cause is probable and was not fully confirmed.
What was done
Replace the failed tantalum capacitors and the blown 2 A fuse in the affected block. Fault isolation was done per the gradient troubleshooting section near the end of the manufacturer's service documentation.
Safety
De-energise and lock out the system, allow the storage capacitors of the gradient amplifier to discharge and verify absence of voltage before working inside the cabinet; repeat the electrical safety tests before the scanner returns to clinical use.
Lesson: When a start-up fault resets but keeps coming back, work from the cabinet's own indicators down to the fuses before changing boards — and treat cooling and humidity as prime suspects in gradient electronics failures.
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.