I can see no model numbers, but the remotes look identical (the default codes definitely are), ergo I see no reason why the one from the 1900 should not control the 3900 (and vice-versa). Note, however, the caveat under the default codes . . . "You may not be able to operate your Yamaha component even if a Yamaha control code is preset as listed above. In this case, try setting another Yamaha remote control code."
The manuals, by the way, can be had from here . . . [Link: yamaha.co.jp]