Consider these conditions and the safety hazards they present:
• Electrical hazards, especially primary power (primary voltage on the frame can cause serious or fatal
electrical shock)
• Explosive hazards, such as a damaged CRT face or a bulging capacitor
• Mechanical hazards, such as loose or missing hardware
To determine whether there are any potentially unsafe conditions, use the following checklist at the beginning
of every service task. Begin the checks with the power off, and the power cord disconnected.
Checklist:
1.
Check
exterior
covers
for
damage
(loose,
broken,
or
sharp
edges).
2.
Power
off
the
computer.
Disconnect
the
power
cord.
3.
Check
the
power
cord
for:
a.
A
third-wire
ground
connector
in
good
condition.
Use
a
meter
to
measure
third-wire
ground
continuity
for
0.1
ohm
or
less
between
the
external
ground
pin
and
the
frame
ground.
b.
The
power
cord
should
be
the
authorized
type
specified
for
your
computer.
c.
Insulation
must
not
be
frayed
or
worn.
4.
Check
for
cracked
or
bulging
batteries.
5.
Remove
the
cover.
6.
Check
for
any
obvious
non-ThinkPad
alterations.
Use
good
judgment
as
to
the
safety
of
any
non-ThinkPad
alterations.
7.
Check
inside
the
unit
for
any
obvious
unsafe
conditions,
such
as
metal
filings,
contamination,
water
or
other
liquids,
or
signs
of
fire
or
smoke
damage.
8.
Check
for
worn,
frayed,
or
pinched
cables.
9.
Check
that
the
power-supply
cover
fasteners
(screws
or
rivets)
have
not
been
removed
or
tampered
with.A
Handling devices that are sensitive to electrostatic discharge
Any computer part containing transistors or integrated circuits (ICs) should be considered sensitive to
electrostatic discharge (ESD.) ESD damage can occur when there is a difference in charge between objects.
Protect against ESD damage by equalizing the charge so that the machine, the part, the work mat, and the
person handling the part are all at the same charge.
Notes:
1. Use product-specific ESD procedures when they exceed the requirements noted here.
2. Make sure that the ESD protective devices you use have been certified (ISO 9000) as fully effective.
When handling ESD-sensitive parts:
• Keep the parts in protective packages until they are inserted into the product.
• Avoid contact with other people.
• Wear a grounded wrist strap against your skin to eliminate static on your body.
• Prevent the part from touching your clothing. Most clothing is insulative and retains a charge even
when you are wearing a wrist strap.
• Use a grounded work mat to provide a static-free work surface. The mat is especially useful when
handling ESD-sensitive devices.
• Select a grounding system, such as those listed below, to provide protection that meets the specific
service requirement.
Note:
The use of a grounding system to guard against ESD damage is desirable but not necessary.
– Attach the ESD ground clip to any frame ground, ground braid, or green-wire ground.
Chapter 1
.
Safety information
3
