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•
Charge
the battery
pack with
the power-off
charge
procedure.
•
1f the
voltage
is not
correct
after the
battery
pack
is
charged, replace
it.
•
If the
voltage
is
correct,
suspect
a
short
circuit or
failure in the
computer.
Go to the
"System
Power
Problems"
on page 17.
•
lf the system starts up with the AC Adapter
connected,
the battery pack removed, and the voltage
of
the battery pack correct, replace the DC/DC
card
and check
if the
system starts
up with only the
battery pack
installed.
If the
system
starts
up,
the
original
DC/DC
card
is
fai ling;
if
the
system still
does
not
start up with the good DC/DC
and
with the
original
battery,
replace the battery pack and confirm
the
system
starts up with the new
battery
and with
the
original
DC/DC
card.
Do
the
following
to
check
to see if the
therrnal
protection
has
tripped:
J.
Meas
ure the resistance between terminal
(-)
and (T).
2.
The
resistance should be from
2
kQ lo
50
kQ. If
the measured resistance is not
in
this
range, replace
the battery pack. If the
resistance
is between 2 kQ
to
5
kQ,
the temperature
of
the battery
pack
is too
high
for
the battery pack to be
charged.
Do
not
charge the battery pack
until
its
resistance is more
than
5.5
kQ.
16
ThinkPad Power
Series 820
System Power Problems
Do the following to
analyze
a short or an open circuit
in
the
computer:
1. Disconnect
both
the battery pack and the AC
Adapter;
then
reconnect them
(see note).
2. Disconnect
and
then reconnect all external
devices
from
the computer
one
by
one and see
if the
same
symptom appears. If
you find a problem
with an
external
device
or
its associated cables, follow
the
maintenance
procedure for
that
device.
3. If
the
same
symptom
remains
with no
external
devices connected,
the
problem
is
in the computer.
Visually
check
the
cables,
wires,
connecters, and
cards for
short
circuits,
open
wires,
or
loose
or
damaged
wires.
Also
check
to
see if
there are any
foreign metal material
in
the
computer. Isolate
the
fai ling part in the
computer
by changing the
FRUs
one
by
one
until
you
find the problem.
Replace
the
DC/DC
card and
the
system
board first.
lf the battery power
becomes
low
quickly,
and all
tests run with no
errors
detected,
replace
the
ba11ery
pack.
4.
If the problem
remains
after
you
have
done all
of
the
preceding,
isolate the
failure
in the computer by
changing
the FRUs
one
by
o ne.
The most probable
faili ng
FRUs
are
the
DC/DC card and the system
board.
5.
If
the
battery
power becomes
low
immediately
after
power-on and no problems are
fo
und
in
other
parts
of the
computer and
all
imemal
tests run without
detecting
any errors,
replace the battery
pack.
Note:
If the power protection mechanism
works,
the
output
voltage from the DC/DC
card and
the
AC
Adapter
continues
to be
blocked.
To cancel
the
mechanism,
disconnect
the
battery pack
and
the
AC Adapter and then reconnect
them.
Hardware
Maintenance
Service
17
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