Fru Replacement Notices; Screw Notices - Lenovo ThinkPad L412 Hardware Maintenance Manual

FRU replacement notices

This chapter presents notices related to removing and replacing parts. Read this
chapter carefully before replacing any FRU.

Screw notices

Loose screws can cause a reliability problem. In the ThinkPad Notebook, 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 Each one 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 215) in your
v Always use new screws.
v Use a torque screwdriver if you have one.
Tighten screws as follows:
v Plastic to plastic
v Logic card to plastic
v Torque driver
v Make sure that you use the correct screw. If you have a torque screwdriver,
v Ensure torque screw drivers are calibrated correctly following country
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tool bag.
Turn an additional 90 degrees after the screw head touches the surface of the
plastic part:
Turn an additional 180 degrees after the screw head touches the surface of the
logic card:
If you have a torque driver, refer to the "Torque" column for each step.
tighten all screws firmly to the torque shown in the table. Never use a screw
that you removed. Use a new one. Make sure that all of the screws are
tightened firmly.
specifications.
90 degrees more
(Cross-section)
180 degrees more
(Cross-section)
75