User Guide

PAMS Technical Documentation Disassembly and Troubleshooting
TME-3
Issue 3 10/03 Nokia Corporation. Page 9
RF Troubleshooting
Introduction to RF troubleshooting
The RF-section of the RL7 module is build around one RF-ASIC (HAGAR, N600). For easier
troubleshooting, the instructions are divided into three sections: transmitter, receiver
and synthesizer.
Component notes:
Apart from key components described in this document here are several discrete compo-
nents (resistors, inductors and capacitors), the troubleshooting of which is done by
checking whether the soldering of each component is OK.
Capacitors can be checked for short circuits and resistors for value by means of an ohm-
meter, but be aware that in-circuit measurements must be evaluated carefully.
Before replacing HAGAR, please check following: are the supply voltages and serial com-
munication signals (coming from baseband to HAGAR) correct?
Please note that the grounding of the PA module is directly below the PA-module so it is
difficult to check or change.
Component handling:
Most RF semiconductors are static discharge sensitive! ESD protection must be taken
care of during repair (use ground straps and ESD soldering irons).
HAGAR and PA are moisture sensitive components; parts must be pre-baked prior to sol-
dering.
Measurement notes:
Measurements must be done using spectrum analyzer with high-frequency high-imped-
ance passive probe (LO-/reference frequencies and RF power levels) and oscilloscope
with a 10:1 probe (DC-voltages and low frequency signals)
Please be aware that all measured voltages or RF levels in this document are rough fig-
ures. Especially RF levels vary due to different measuring equipment or different ground-
ing of the used probe. When using RF probe usually a good way is to use metallic
tweezers to connect probe ground to PWB ground as close to measurement point as pos-
sible.