Renex ward X-ray unit (2020): unit down, high-voltage inverter fault
What happened
A ward X-ray unit was reported completely inoperative. The engineer first had to identify the inverter board from photographs and suspected a fault in the high-voltage inverter.
What was checked
- Identified the inverter board, then inspected and cleaned it.
- Checked the 100 Ω resistor reported in the case, standing in series with the inverter supply circuit.
- Tested the inverter transistors and diodes; the engineers found two failed transistors.
Cause
A cooling fan wire had come loose. Without forced airflow the inverter overheated and two of its switching transistors burned out.
What was done
The failed inverter transistors were replaced and the fan lead was reconnected and secured; the unit reportedly returned to normal operation after the repair.
Safety
Discharge and verify the high-voltage capacitors before touching the inverter, and carry out the electrical safety and X-ray output checks before the unit goes back into clinical use.
Lesson: A single loose cooling fan wire can destroy expensive inverter transistors, so whenever an inverter fails, check the fan connections and airflow, and secure the wiring properly before closing the unit up.
Covered in the course: X-ray 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.