It was reported that the controller's display was malfunctioning.A controller was returned for evaluation.Various analyses were conducted and reviewed in order to evaluate the performance of the device in relation to the reported event.Failure analysis of the returned controller revealed that the device passed visual inspection and initially passed functional testing.It was noted that the controller contained a fairchild metal-oxide-semiconductor field-effect transistor (mosfet) on the power board.A controller with a fairchild mosfet may operate at a higher temperature, but still within the manufacturer's temperature operating range.Based on this observation, the controller was allowed to run for an extended period of time to determine if the heat generated by the mosfet may have contributed to the reported event.The results revealed that the display was visually dimmer, confirming the reported event.As a result, the most likely root cause of the reported event can be attributed to a fairchild mosfet that was operating at a higher temperature, causing the display to become dimmer.Heartware will submit a supplemental report when new facts arises which materially alters information submitted in a previous mdr report.
|