JCV are provided in different resolution (high&low) to fit different displays, the one posted in the first page has a low resolution, not good for new series devices like 37xx . Should work in 850, but better to test it in simulation mode.
I've not had a chance to personally test it yet, but I was able to independently confirm that its SHA signature matches that of an "official" one for the 850, so I'm 99.9% sure it will work.
Bookmarks