User Guide

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 fills up. Normal behaviour of the voltage is

described in the figures below.

Figure 38 Charging backup battery

Figure 39 Discharging backup battery

If the voltage rises and falls quickly, check whether 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, RETU

is faulty. Replace RETU.

RM-198

BB Troubleshooting and Manual Tuning Guide Nokia Customer Care

Issue 1 COMPANY CONFIDENTIAL Page 6 –15