Lenovo 3000 N200 - Manual (Page 48)

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:
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 152) in your
tool bag.
v
Always use new screws.
v Use a torque screwdriver if you have one.
Tighten screws as follows:
v Plastic to plastic
Turn an additional 90 degrees after the screw head touches the surface of the
plastic part:
90 degrees more
(Cross-section)
v
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)
v
Torque driver
If you have a torque driver, refer to the “Torque” column for each step.
v
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.
v
Ensure torque screwdrivers are calibrated correctly following country
specifications.
Retaining serial numbers
This section includes the following descriptions:
v
“Restoring the serial number of the system unit” on page 43
FRU replacement notices
42
MT 0689, 0768, and 0769