Chuck
An IOS router such as the 1700 does not have a default IP address. Some of the IOS routers have SDM installed and the installation of SDM does provide an IP address as a starting place. If youi "inherited" this 1700 does that imply that it has been in use? If so I doubt that even if it has SDM that it would still use the beginning address from SDM.
The best way to access the 1700 to make config changes is not through a network interface but is through the console port. You connect to the router console port using a PC serial interface and a console cable and some terminal emulation software such as Hyperterm.
Note that whether you access the 1700 by network interface or by console port you will probably need passwords to get into the 1700. If you do not have passwords then there is a password recovery procedure which you can use. This requires connection through the console port.
HTH
Rick
HTH
Rick