Lenovo 07632VU, Hardware Maintenance Manual

Page: 48 / 126

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 the Lenovo 3000 computer, this
problem is addressed with special nylon-coated screws that have the following
characteristics:
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They maintain tight connections.
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They do not easily come loose, even with shock or vibration.
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They are harder to tighten.
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Each one should be used only once.
Do the following when you service this machine:
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Keep the screw kit (for the P/N, see “Miscellaneous parts” on page 114) in your
tool bag.
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Always use new screws.
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Use a torque screwdriver if you have one.
Tighten screws as follows:
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Plastic to plastic
Turn an additional 90 degrees after the screw head touches the surface of the
plastic part:
90 degrees more
(Cross-section)
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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)
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Torque driver
If you have a torque driver, refer to the “Torque” column for each step.
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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.
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Ensure torque screwdrivers are calibrated correctly following country
specifications.
Retaining serial numbers
This section includes the following descriptions:
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“Restoring the serial number of the system unit” on page 43
FRU replacement notices
42
MT 0763 and 0764