Dell 5100cn Color Laser Printer - Manual (Page 221)

8. Reattach the paper tray cover to the back of the printer.
Removing the Optional Multi Protocol Card
1. Make sure that the printer is turned off and unplug all cables including the power cord from the rear of the printer.
2. Pull the paper tray cover so that the top edge tilts out, then lift the paper tray cover off its hinges.
3. Remove the three screws on the controller card from the back side of the printer.