Backup Battery Troubleshooting - Nokia n81 Service Manual

RM-179; RM-223
Baseband Troubleshooting

Backup battery troubleshooting

Verify that the backup battery is empty (U<1V). Switch the phone on. Measure voltage of the battery when
the main battery is connected to the phone and the phone is switched on.
Wait a few minutes and monitor that the backup battery voltage rises. Switch off the phone, disconnect the
main battery and monitor that the voltage of the backup battery decreases. Normal behaviour of the voltage
is described in the figures below.
Figure 15 Charging backup battery
Figure 16 Discharging backup battery
If the voltage rises and falls quickly, check whether either G2200 or C2233 is broken or short-circuited. Backup
battery can be also dead. If the voltage stays ~0V, check resistance VBACK against GND. If there is no short
circuit, AVILMA is faulty. Replace AVILMA.
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