Rf Troubleshooting; Introduction; Abbreviations In Fault Finding Charts - Nokia NPM-2NX Troubleshooting Manual

NPM-2NX
Troubleshooting

RF Troubleshooting

Introduction

Measurements should be done using spectrum analyzer and high-frequency probe (Local
and reference frequencies and RF-power levels in intermediate stages of chain). Oscillo-
scope is used to measure DC-voltages and low frequency signals. Multimeter is also use-
ful measurement equipment in faultfinding. Also cellular tester is needed in order to
perform tests mentioned in this document.
External RF connector is implemented to design improving reliability of the measurement
results and should be in use when it is reasonable.
RF-section is mainly build around of SAFARI GTE3.2 IC (N801). The RF block has separate
external filters, UHF and VHF synthesizer, Power Amplifier, front-end and up converter
circuit for both frequency band.
To simplifying troubleshooting, this RF troubleshooting document is divides into three
bigger sections: Receiver-, Transmitter and Synthesizer parts. The tolerance is specified
for critical signals/voltages.
Before changing single ASICS or components, please check the following things:
1. The soldering and alignment marks of the ASICS
2. Supply voltages and control signals are OK
The PA-module is static discharge sensitive! So ESD protection must be used when
dealing with PA-IC (ground straps and ESD soldering irons). The PA is also moisture sen-
sitive components and it is important to follow additional information about handling
the component. So it is recommended to wear EDS protected clothes and shoes when-
ever handling radio module unit! Also wrist-grounding strap should be used.
The shield lid must be always replaced with new one after it is opened. Plate bands under
shield lid could be cut but always bend plate ends downwards after repairing. Plate ends
should NOT touch shield lid after lid is installed. Note also that there are no short circuits
caused by plate ends on PWB.

Abbreviations in fault finding charts

BB
BPF
f:
HB
LB
LO
P:
PA
PWB
Page 26
Base band
Band pass filter
Frequency of signal (measured with spectrum analyzer)
High band
Low band
Local Oscillator
Power of signal in decibels (dB) (measured with spectrum analyzer)
Power Amplifier
Printed Wiring Board
ãNokia Corporation
CCS Technical Documentation
Issue 1 07/02