User Guide

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.
FRU replacement notices
56 ThinkPad T20, T21, T22, T23 (MT 2647/2648)