Editing IBM 5120 Maintenance Guide (section)

== Opening the System Unit ==

Tools: Philips #2 screwdriver, T15 / T20 Torx, anti-static strap, high-voltage probe.

# Power off and unplug all cables (mains, keyboard, printer, communications).
# Remove the cover fasteners around the back of the chassis (typically 4–6 screws).
# Lift the cover — '''the 9-inch CRT and deflection sub-chassis remain attached to the lower chassis''', unlike the 5100 / 5110 where the CRT is in the upper shell.
# Inside layout (looking from the front):
:: '''9-inch CRT''' centred behind the front bezel; deflection board mounted to the side of the CRT cradle.
:: '''2 × 8-inch floppy drives''' below the CRT, mounted vertically in a drive cage.
:: '''Main PSU''' at the rear left.
:: '''PALM board''' and ROS / RWS cards on a backplane behind the drive cage.
:: '''Keyboard connector''' on the front edge.