User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 8
Original 11/97
Baseband Troubleshooting
Overview
Baseband oriented failures are usually found out during Flash updating of
the phone, the phone should be started to minimum mode and current
consumption measured. If current consumption is within acceptable limits
and MBUS registration is OK, flash is programmed. If flash programming
fails, service software can be used to activate MCU self tests. During the
MCU self tests all the major components of the baseband are tested.
Every test returns number of the test and result ( OK / failed ).
If phone can be flashed and all self tests performed, the baseband is
mainly OK.
In case of current consumption/MBUS registration failure, the phone must
be taken to more specific measurements of voltages, clocking signals and
states of reset signals.
The flow diagrams give the overview of the blocks. The purpose is to
proceed through the flow diagram so that, if answer is YES for the asked
question, go straight to the next level, but if answer is NO, take the
sub–branch.
Required servicing equipment:
Service software
Power supply (1.0 A)
Digital multimeter
Oscilloscope
Modular cable
RS232/MBUS adapter
Soldering iron and related tools.
Current consumption failures in flash station
Current consumption can fail in three ways. Typical to all these failures is
that phone can not be programmed or tested via MBUS. The most
common failure is that phone takes normal current during startup and
after a few seconds all circuits are powered down. The reason for this
could be in power, clock or reset distribution of the phone. In cases where
phone does not take current at all or phone takes all available current the
reason could be defective PSL_+3V(N500) or bad soldering (short or
open) around PSL_+3V(N500).