User Guide

Backup battery troubleshooting

Verify that the backup battery is empty (U<1V). 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 is rised. Switch off the phone and disconnect

the main battery and monitor that voltage of backup battery is filled. Normal behaviour of the voltage is

described pictures.

Figure 38 Charging backup battery

Figure 39 Discharging backup battery

If the voltage rises and falls quickly, battery is dead. If the voltage stays 0V, check resistance VBACK<-> GND:

If there is no short circuit, Retu is faulty. Replace Retu.

RM-86

BB Troubleshooting and Manual Tuning Guide Nokia Customer Care

Issue 1 COMPANY CONFIDENTIAL Page 6 –15