Nokia 2255 Manual

Also see for 2255: User guide User guide Antenna Description and Troubleshooting Baseband Description and Troubleshooting Disassembly/Assembly

Contents

2255 (RM-97)RF Description and Troubleshooting Nokia Customer CarePage 4 ©2005 Nokia Corporation Company Confidential ISSUE 1 10/2005Preliminary RF TroubleshootingThe following sections identify steps to troubleshoot some common RF issues.Mobile Terminal Cannot Make a CallVerify the following if the mobile terminal cannot make a call:1. The mobile terminal is in Normal Mode (i.e., the mobile terminal is searching fora signal, net server is on).2. The Preferred Roaming List (PRL) is loaded into the mobile terminal.3. The mobile terminal is tuned and has passed tuning. Read the tuning parametersusing the Batch Tune component in Phoenix. An untuned mobile terminal has allzeros in the tuning file.4. The call box channel is set for a channel in PRL.5. The SID is correct and entered into the mobile terminal.6. The VCTCXO is centered as described in the "VCTCXO Manual Tuning" section onpage 34.7. The transmitter and receiver are working properly in Local Mode. See"Transmitter Troubleshooting" on page 8 and "ReceiverTroubleshooting" on page 16 for detailed information.Tx Power LowComplete the following steps if Tx power is low:1. Use Phoenix to turn on the transmitter in Local Mode.2. Perform a visual inspection of the PWB under a microscope to check for theproper placement, rotation, and soldering of components.3. Look for the presence of a Tx signal on a spectrum analyzer at the correctfrequency.• If a signal is present but off-frequency, check the synthesizers for properfrequency and amplitude. One of the synthesizers may be unlocked or theVCO has no output signal.• If a signal is not present or is present but is low in amplitude, check theprobing diagrams to determine where in the chain the fault occurs.)4. Ensure that the power supplies to the Tx have the correct voltage.5. Ensure that the AGC PDMs are set for the desired Tx power and that the AGCvoltages are correct.