How did you make the dump? If you just did it from the OB-6's front panel without running anything on your computer to capture it, it would have gone nowhere.
A librarian program like the Soundtower editor can receive the dump and organize the patches within it for you and let you edit them on your PC. Or if you just want a backup, something like Midi-OX can do it (if you have a Mac, there are similar programs to this, I'm not familiar with them as I'm a PC guy). If you use Midi-OX, you'd set it up to receive a sysex file from your synth, then you'd send it from the OB-6, and once it's received, you can save it to wherever you'd like.
I don't know offhand how Cubase handles sysex dumps. I think it can record them into a midi track, and "play" them back into the synth, but saving as a .syx file is simpler.