Dräger 760: fails power-on self-test on the O2 solenoid test
What happened
On power-up the anaesthesia machine kept failing its power-on self-test (POST) at the O2 solenoid test, so it would not come ready for use.
What was checked
- The engineers first attempted the inlet oxygen pressure regulator calibration (a manufacturer service procedure) — it would not complete.
- They then checked the O2 sensor and found it out of calibration.
Cause
An out-of-calibration O2 sensor: because of it, the inlet oxygen pressure regulator calibration could not pass, and the O2 solenoid test failed as a result.
What was done
The O2 sensor was recalibrated and the inlet oxygen pressure regulator calibration completed — procedures from the manufacturer's service documentation, done by authorised personnel. After that POST was re-run and, in this case, all tests passed.
Safety
Before any work on the pneumatic circuit, isolate and vent the oxygen and air supplies — oxygen-enriched surroundings sharply raise fire risk, and the machine should return to clinical use only after a full self-test.
Lesson: A failing O2 solenoid test often traces back to a drifted O2 sensor, so recalibrate the sensor before suspecting valves or other hardware.
Covered in the course: Anaesthesia Machine 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.