The replaced printed circuit board of the user interface (pcb mobi 1) was available for investigation.During a functional test in a laboratory device the reported behavior could be confirmed.The internal communication master processor (coma) was no longer functional.Root cause was a failure of a capacitor in the power supply of the printed circuit board.The above mentioned processor is monitored by another processor on the pcb-mobi, which detected the coma failure and responded as specified for this situation with a shutdown of the gas mixer and the ventilator together with a corresponding gas + vent.Fail alarm.If the function of the lp-mobi is disturbed in a way that it is not possible to generate the acoustic alarm via the loudspeaker, the acoustic alarm is generated by the piezo-buzzer of the power supply.In any case, manual ventilation with up to 12l/min o2 and anesthetic gas dosing remains available.The pcb-mobi1 was replaced and the device was finally tested according to dräger specification.Further measures are not required.The number of similar cases, related to the same root cause, is within the expected range of the respective risk assessment and thus accepted.
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