Power
system
checkout
To
verify
a
symptom,
do
the
following:
1.
Turn
off
the
computer.
2.
Remove
the
battery
pack.
3.
Connect
the
ac
adapter.
4.
Check
that
power
is
supplied
when
you
turn
on
the
computer.
5.
Turn
off
the
computer.
6.
Disconnect
the
ac
adapter
and
install
the
charged
battery
pack.
7.
Check
that
the
battery
pack
supplies
power
when
you
turn
on
the
computer.
If
you
suspect
a
power
problem,
see
the
appropriate
one
of
the
following
power
supply
checkouts:
v
“Checking
the
ac
adapter”
v
“Checking
operational
charging”
on
page
30
v
“Checking
the
battery
pack”
on
page
30
v
“Checking
the
backup
battery”
on
page
31
Checking
the
ac
adapter
You
are
here
because
the
computer
fails
only
when
the
ac
adapter
is
used.
v
If
the
power
problem
occurs
only
when
the
ThinkPad
Essential
Port
Replicator
is
used,
replace
the
port
replicator.
v
If
the
power-on
indicator
does
not
turn
on,
check
the
power
cord
of
the
ac
adapter
for
correct
continuity
and
installation.
v
If
the
computer
does
not
charge
during
operation,
go
to
“Checking
operational
charging”
on
page
30
To
check
the
ac
adapter,
do
the
following:
1.
Unplug
the
ac
adapter
cable
from
the
computer.
2.
Measure
the
output
voltage
at
the
plug
of
the
ac
adapter
cable.
See
the
following
figure:
1
2
3
(20V)
Pin
Voltage
(V
dc)
1
+20
2
0
3
Ground
Note:
Output
voltage
of
pin
no.2
of
the
ac
adapter
may
different
from
the
one
you
are
servicing.
3.
If
the
voltage
is
not
correct,
replace
the
ac
adapter.
4.
If
the
voltage
is
acceptable,
do
the
following:
v
Replace
the
system
board.
v
If
the
problem
persists,
go
to
“ThinkPad
T400
and
R400
(14.1-inch
widescreen)”
on
page
47.
Note:
Noise
from
the
ac
adapter
does
not
always
indicate
a
defect.
General
checkout
29
Summary of Contents for XT904UT
Page 1: ...ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
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Page 3: ...ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
Page 8: ...vi ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
Page 24: ...16 ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
Page 30: ...22 ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
Page 40: ...32 ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
Page 232: ...224 ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
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