Checking
the
backup
battery
Do
the
following:
1.
Power
off
the
computer,
and
unplug
the
ac
adapter
from
it.
2.
Turn
the
computer
upside
down.
3.
Remove
the
battery
pack
(see
“1010
Battery
pack”
on
page
63).
4.
Remove
the
backup
battery
(see
“1060
Backup
battery”
on
page
72).
5.
Measure
the
voltage
of
the
backup
battery.
See
the
following
figure.
Red (+)
Black (-)
Wire
Voltage
(V
dc)
Red
+2.5
to
+3.2
Black
Ground
v
If
the
voltage
is
correct,
replace
the
system
board.
v
If
the
voltage
is
not
correct,
replace
the
backup
battery.
v
If
the
backup
battery
discharges
quickly
after
replacement,
replace
the
system
board.
General
checkout
31
Summary of Contents for XT904UT
Page 1: ...ThinkPad T400 and R400 14 1 inch widescreen Hardware Maintenance Manual ...
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