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[SK-3500 Super-S3] USB 3.0 interface not working on El Capitan

We have received some reports from users having problems with the SK-3500 Super-S3 and its USB 3.0 interface after upgrading to El Capitan (Mac OS X 10.11). It seems that not everyone is affected by this problem and the solution differs from user to user. A common workaround to this problem is using a USB 2.0 cable instead. The current firmware update on our website does address the compatibility with Mac computers but it's not related to El Capitan. Still, if you haven't updated the firmware yet, try this first.

To further troubleshoot this issue, we have collected a list of tips to narrow down the problem and fix this issue.

  1. Disconnect and reconnect the USB cable while the device and the computer is turned on.
  2. Restart the system.
  3. Update the OS to the latest version.
  4. Reset SMC, see https://support.apple.com/en-us/HT201295.
  5. Reset NVRAM, see https://support.apple.com/en-us/HT204063.
  6. If the NTFS Paragon driver is used, uninstall or reinstall the latest version. To uninstall, click on Apple > System Preferences > Paragon NTFS for Mac OS X. Click the Info tab and select uninstall. Reboot the Mac. Then test without or download and install the updated version.
  7. Use the disk utility and mount the drive manually.
  8. Use the command 'diskutil info -all' to list all drives, then mount the USB drive manually with 'diskutil mount [device identifier]'.
  9. Boot to safe mode, then leave safe mode by restarting normally. See https://support.apple.com/en-us/HT201262
  10. Use a USB hub in between the computer and the USB device, instead of connecting the USB device directly to the computer.
  11. Install a fresh copy of El Capitan on an external drive and boot from that to see if that makes any difference. If necessary, re-install the system.

If none of the above helps and you have access to a Windows based PC, we have prepared the advanced firmware utility for the USB interface at http://www.inxtron.com/files/ISIS_v1.59.zip. Please download it, store it on your Windows computer and unzip the file. To install it, double-click on "RemoteCommsInstaller_V1_25_0001.msi". Once the driver has been installed, run the installer (*.exe) for either the 32-bit or the 64-bit Operating System.

Please be aware that updating and changing the firmware might, in the worst case, fail and brick your unit. inXtron cannot be held responsible for any damage caused by misuse of this utility! Only continue with the following instructions if you understand these risks.

  1. Connect the external drive using the USB interface (USB 2.0 or USB 3.0) and turn on the power. The drive does not have to be installed for this procedure.
  2. Start the "Flash Editor".
  3. Select "Advanced".
  4. On the left side under "Firmware", you should now be able to see your device and the current firmware version on the device. If not, try disconnecting and re-connecting the USB cable.
  5. On the right side under Device Configuration >> USB Details, check if the option "Support UAS + Streams" is enabled or disabled. If it's currently enabled, disable it and continue. If it's already disabled, stop and abort at this point.
  6. Click the "Write" button beside Device Configuration to upload the changes.
  7. Close the firmware utility and restart the external drive.
  8. Test the drive on the Mac again now.

If disabling the UAS option did not fix the problem or if the option is greyed out and you are unable to disable it, erase the firmware and upload an older version as described below.

  1. Use the same firmware utility as seen above and make screenshots of all your current settings. This will be used for reference later.
  2. Download the ZIP file at http://www.inxtron.com/files/U3100_20110318_Release.zip and store the *.pfw file inside it on your Windows computer.
  3. Connect the SK-3500 via USB, turn it on and start the firmware utility.
  4. Make sure the device has been recognized and then click on "Erase" to erase the current firmware.
  5. On the left side under Firmware, load the *.pfw file and then click "Write" to upload the firmware.
  6. Once the firmware update has completed, your device should be running the same firmware version but with an older date (March 18, 2011).
  7. On the right side under USB Details, disable the support for UAS and then click on "Write" beside device configuration to upload the change.
  8. After erasing and uploading the firmware, you will find that some of settings are different from before (e.g. manufacturer string, vendor ID, device name, etc.). Use the screenshots from earlier to find the differences and change the settings accordingly. Click "Write" to upload the changes.
  9. Test the SK-3500 on your Mac again now.