Lenovo 2516ADU, Hardware Maintenance Manual, Page: 87 / 203

Chapter 7. 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:
• They maintain tight connections.
• They do not easily come loose, even with shock or vibration.
• They are harder to tighten.
• Each one should be used only once.
Do the following when you service this machine:
• Keep the screw kit (for the P/N, see “Miscellaneous parts” on page 177) in your tool bag.
• Always use new screws.
• Use a torque screwdriver if you have one.
Tighten screws as follows:
• Plastic to plastic
Turn an additional 90 degrees after the screw head touches the surface of the plastic part:
90 degrees more
(Cross-section)
• 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)
• Torque driver
If you have a torque driver, refer to the “Torque” column for each step.
• Make sure that you use the correct screw. If you have a torque screwdriver, 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.
• Ensure torque screw drivers are calibrated correctly following country specifications.
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