Mercury Elite Pro Dual (U3/FW800): FireWire 800 and Yosemite

Created on: November 8, 2016
Last updated: November 8, 2016

If a customer has a Mercury Elite Pro Dual (OWCMED3FR---), and the device will not mount when connected to a Mac that is running 10.10 Yosemite, there may not be anything wrong with the enclosure. We have seen this behavior with a number of FireWire 800 enclosures but only intermittently — it does not always occur. The easy workaround is to have the customer restart Yosemite while the FireWire 800 enclosure is connected. Make sure the dedicated power supply is also connected and that the power switch is set to ON.

Please follow these steps before setting up an RMA. We have seen units come back that passed testing because this simple fix was not attempted.

To our knowledge this issue does not occur with either 10.9 or 10.11 or later.