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U31-70 Hardware Maintenance Manual
FRU replacement notices
This section presents 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 the Lenovo computer, 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 in your tool bag.
• Carefully remove screws for reuse when replacing FRUs.
• Use a torque screwdriver if you have one.
Tighten screws as follows:
•
Plastic to plastic
Turn an additional 90° after the screw head touches the surface of the
plastic part:
more than 90°
(Cross-section)
•
Logic card to plastic
Turn an additional 180° after the screw head touches the surface of the
logic card:
more than 180°
(Cross-section)
•
Torque driver
If you have a torque screwdriver , refer to the “Torque” column for each step.
• Make sure that you use the correct screws. If you have a torque screwdriver,
tighten all screws firmly to the torque shown in the table.
Carefully remove
screws for reuse when replacing FRUs. Make sure that all screws are
tightened firmly.
• Ensure torque screwdrivers are calibrated correctly following country
specifications.
