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PAMS
Technical Documentation
Introduction
RF–measurements must be done using a spectrum analyzer and an high–
frequency probe. (Local and reference frequencies and RF power levels in
the intermediate stages of the chain) Oscilloscope is used to measure DC–
voltages and low frequency signals. Multimeter is also a useful measure-
ment equipment in fault finding.
The external RF connector must be used when reasonable to improve the
reliability of the measurement results.
The RF–section is mainly built around the PLUSSA IC (N750). The RF block
has separate external filters, UHF synthesizer, Power Amplifier , TX Driver,
frontend and upconverter circuit for both frequency bands.
TDMA1900 mode the external regulator is used to provide supply voltage for
RF parts.
Before changing single ASICs or components, please check the following :
1. The soldering and connections of pins of the ASICS are OK
2. Supply voltages and control signals are OK
3.Signals of the synthesizers are coming to ASICS. This to prevent the un-
necessary changing of the ASICS.
NOTE! Grounding of the PA–IC is directly underneath so it is hard to check.
The PA–module is static discharge sensitive! So ESD protection must be
used when dealing with PA–IC (ground straps and ESD soldering tools). The
PA is also a moisture sensitive components and it is important to follow addi-
tional information about handling the component.
There are still lots of discrete components (resistors, inductors and capaci-
tors) troubleshooting of which comprises just checking that the component
is soldered or it is not missing from PCB.
Abbreviations in RF–fault finding charts
TP
BB
f:
LO
P:
PA
PCB
PLL
RF
RX
T:
TX
UHF
V:
VCO
VHF
AF:
Original 11/99
Disassembly & Troubleshooting Instructions
Test Point
Baseband
Frequency of signal (measured with spectrum analyzer)
Local Oscillator
Power of signal in desibels (dB)
(measured with spectrum analyzer)
Power Amplifier
Printed Circuit Board
Phase Locked Loop
Radio Frequency
Receiver
Time between pulses
Transmitter
Ultra High Frequency
Voltage of signal (measured with oscilloscope)
Voltage controlled oscillator
Very High Frequency
Audio Frequency
NSC/W–1/3
In the
Page 5
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Table of Contents
Troubleshooting
