Opera T90: contactor will not pull in at startup
What happened
At startup the console hung on code 099 (as reported in the case), the contactor in the cabinet would not pull in, and 220 V was not fed to the transformer.
What was checked
- The engineers checked the emergency stop buttons first — the common weak point on these units, as noted in the case.
- They rang out the limit switches in the chain with a meter.
- They went through the limit switches on the X-ray stand (URI); one switch that read as good on the meter turned out to be the one breaking the circuit.
Cause
The engineers found a faulty limit switch on the X-ray stand (URI): it showed continuity on a static meter test but broke the chain under real conditions, so the contactor did not pull in and no power reached the transformer (as reported in the case).
What was done
The fault was localised to that switch; the fix was a procedure from the manufacturer's service documentation, done by authorised personnel, and the faulty limit switch was put in for replacement — as reported, the unit ran again afterwards, with the switch replacement still pending.
Safety
Isolate the cabinet before working on the contactor circuit, and never return the unit to clinical use while any limit switch or interlock remains out of circuit — restore and verify the full protective chain first.
Lesson: A limit switch that passes a static continuity test can still fail in service, so load-test or substitute the suspect switch before condemning the rest of the chain.
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.