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Checking the Car Battery Adapter (700
only): If the output voltage from the cigarette lighter
socket of the car is less than 10.5 V dc, the power-on
indicator on the car battery adapter blinks and a noise can
be heard continuously.
1. Unplug the car battery adapter cable from the
connector, if connected.
2. Plug the car battery adapter into the cigarette lighter
socket.
Note: If the adapter is already plugged in, be sure to
unplug the adapter from the cigarette lighter
socket, then plug it into the socket again.
3. Measure the output voltage of the car battery adapter
cable. See the following figure.
1
2
If the voltage is correct and the power-on
indicator on the car battery adapter is on all the
time, the car battery is working correctly.
Replace the voltage converter. If the problem is
not resolved when the voltage converter is
replaced, go to “Checking the Voltage Converter
(700, 700C)” on page 77 or “Checking the
Voltage Converter (720, 720C)” on page 78.
If the voltage is outside the normal voltage
range, do one of the following:
– Try the above test procedures using a
different car, if one is available.
– Replace the car battery adapter if the
computer works with the AC adapter but
does not work with the car battery adapter.
Note: If the output voltage from the cigarette lighter
socket of the car is less than 10.5 V dc, the
power-on indicator on the car battery adapter blinks
and a continuous noise can be heard. Have the
car battery serviced.
Pin Voltage (V dc)
1 +19.0 to +21.0
2 Ground
ThinkPad 700, 700C, 720, 720C (9552) 73