Mindray 5150: aperture voltage alarm not cleared by rinsing
What happened
On a Mindray 5150 hematology analyzer the RBC aperture kept flagging abnormal aperture voltage; repeated aperture rinsing, reported in the case, did not clear the message.
What was checked
- Repeat aperture rinses and watch the message timing — the engineers found it came back every time.
- Inspect the aperture electrodes for buildup and correct seating.
- Measure the diluent volume actually delivered to and drained from the aperture bath against the expected fill and drain.
- Check that all covers and shields close and seat fully.
- On the 30s variant, check the chamber for moisture — in a separate case a wet chamber gave the same fault.
Cause
The cause reported in the case was diluent underfill into the aperture bath, traced to the diluent valve not delivering the full volume — reported as valve No. 13 on the 5150. In a separate 30s case the same message came from a wet chamber.
What was done
Confirm the fill volume, then service or replace the underfilling valve (valve No. 13 in the case), make sure every cover and shield seats fully, and in the wet-chamber scenario dry the chamber completely. The fault was reported cleared after this.
Safety
Treat all fluid paths and spills as potentially infectious, and after any aperture or valve work run decontamination and quality control before the analyzer goes back to patient samples.
Lesson: An aperture voltage alarm describes the conductivity around the aperture, so prove diluent volume, cover closure and chamber dryness before suspecting the aperture itself.
Covered in the course: Lab Analyser 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.