Great question. I found an article from 2011: http://www.theglobeandmail.com/sports/hockey/globe-on-hockey/how-the-conn-smythe-voting-shakes-down/article615167/ "It's generally three voters per representative city in the final [...] and then the rest of the votes are divided among writers who have covered most or all of the playoffs up to that point."
Re: Ask Meme
From: (Anonymous)"It's generally three voters per representative city in the final [...] and then the rest of the votes are divided among writers who have covered most or all of the playoffs up to that point."