IBM T23 Hardware Maintenance Manual - Page 62

FRU replacement notices FRU replacement notices This section contains notices related to removing and replacing parts. Read this section carefully before replacing any FRU. Screw notices Loose screws can cause a reliability problem. In IBM ThinkPad computer, this problem is addressed with special nylon-coated screws that have the following characteristics: v They maintain tight connections. v They do not easily come loose, even with shock or vibration. v They are harder to tighten. v They should be used only once. Do the following when you service this machine: v Keep the screw kit (for the P/N, see "Miscellaneous parts" on page 167) in your tool bag. v Always use new screws. v Use a torque screwdriver if you have one. Tighten screws as follows: v Plastic to plastic Turn an additional 90 degrees after the screw head touches the surface of the plastic part: 90 degrees more (Cross-section) v Logic card to plastic Turn an additional 180 degrees after the screw head touches the surface of the logic card: 180 degrees more (Cross-section) v Torque driver If you have a torque driver, refer to the "Torque" column for each step. 56 ThinkPad T20, T21, T22, T23 (MT 2647/2648)