OKay so we're all up with the time machine plot.
And about the reason, although tripping over a cord sounds like something teenagers would do while horsing around. Randomly setting it to 1692 seems a bit...Well random.
How about this;
After the scientists have finished perfecting the time machine, they start a discussion that soon turns to an argument about where they should go and if they should interfere with certain horrific events, like the Holocaust or Slavery. However a few scientists argue that tampering with those unfortunate key events would most likely change something in the future, so another scientists suggests an event that was still terrible but was less likely to mess up the future (present day).
The scientist (let's call him Tim) suggests 1692 and another argument ensues, because they still think its risky. Finally the team decide to take a break, and cool their heads. And as they leave, Tim hangs back, he seems to be having an internal battle with himself, as they key in the year. Tim wants to go back and save someone, anyone. Their finger hovers above the 'Launch' button, but before they can act, another scientist calls them to 'Come on and eat already!' and they go.