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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
4.
Remove
the
backup
battery
(see
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.
32
ThinkPad
T61
and
T61p
(14.1-inch)
Hardware
Maintenance
Manual