IBM F50 RS/6000 7025 - Manual (Page 156)

6. If you have a modem or fax machine attached to the system, disconnect the
telephone line.
7. Unplug all power cords (cables) from electrical outlets.
Note the location of the following; then disconnect them from the back of the
system:
Power cord
Display cable
Keyboard cable
Any other cables and cords
The back of your system looks similar to the following.
5-12 IBM RS/6000 7025 F50 Series User's Guide