Lenovo B575 FRU replacement notices, Screw notices, Plastic to plastic, Logic card to plastic

Lenovo B575 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.

•Always use new screws.

•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. Never use a screw that you removed. Use a new one. Make sure that all screws are tightened firmly.

•Ensure torque screwdrivers are calibrated correctly following country specifications.

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