Backup Battery Troubleshooting - Nokia RM-51 Service Manual

Nokia Customer Care
Reading
VBAT SCAL
VCHAR
lCHAR
BSI
Btemp

Backup battery troubleshooting

A symptom of a backup battery fault is that Real Time Clock loses the correct time during short battery removal.
The same symptom can also be seen when the backup battery is empty. About 30 minutes is needed to fully
charge the backup battery in the device.
Note: The backup battery is only charged at the same time as the main battery or when the device is
in the LOCAL or TEST mode.
Always check the backup battery visually for any leakage or any other visual defect.
Check that the backup battery is correctly mounted in the device before closing the cover.
Check with Phoenix that the backup battery is OK.
Measure the voltage of the backup battery.
• Normal operation when the voltage is > 2.0V.
• Fully charged when the voltage is about 3.2V.
Enable the backup battery charging (start to charge the main battery or boot the device to LOCAL or TEST mode).
Measure the voltage of the backup battery during charging, it should rise if it is not 3.2V yet.
When the voltage is over 2.0V for certain, check the backup battery with Phoenix.
Page 6–18
Figure 95 ADC reading window in Phoenix
Table 4 Maximum tolerances
Check point
4.2V
8.4V
500mA
75k (BL-5B)
273K (47k)
Company Confidential
Copyright ©2005 Nokia. All Rights Reserved.
Baseband troubleshooting
Tolerance
±25mV
±40mV
±20mV
±1.3kohm
+5K
9238460 (Issue 1)
RM-51