An ohmmeter will tell you what you need to know..Is the transformer a single voltage primary? It may have a 110v and 120v primary, I have one like that , and you can wire it for either, the output will be slightly higher if you feed 120v in on the 110 winding. It probably a safe bet that one of the primary connections is the white, using an ohmmeter connect from white to brown. Then connect from white to black, the higher resistance should be the 120v, the lower resistance 110v. If one lead is ground you should read continuity from the case to this wire..If it's a
120/240 primary the high resistance connection will produce only about 7v
on the secondary..