Introduction To Rf Troubleshooting - Nokia RM-164 Service Manual

Table of Contents

RM-164

RF Troubleshooting and Manual Tuning Guide

Introduction to RF troubleshooting

On the following pages you will find a step-by-step troubleshooting procedure and reference measurements

at the relevant signal points. For functional descriptions, please refer to the System module section.

Notes on reference measurements

All measurements must be done using:

• spectrum analyser with a high-frequency high-impedance passive probe (LO-/reference frequencies and

RF power levels)

• oscilloscope with a 10:1 probe (DC-voltages and low frequency signals)

Important:

or where there are no transmissions on the same frequencies. This may disturb sensitive receiver

measurements.

Repairing this phone - important

The RF section of the phone is built around one RF ASIC. Before changing the RF ASIC, please make sure that

supply voltages and serial communication coming from baseband to RF are OK.

Please note that the grounding of the FEM module is directly below the FEM module. Therefore, it is difficult

to check or change the module.

Most RF semiconductors are static discharge sensitive! ESD protection must be taken care of during repair

(ground straps and ESD soldering irons). The RF ASIC and FEM are moisture sensitive, so parts must be pre-

baked prior to soldering.

In addition to key components, there are lot of discrete components (resistors, inductors and capacitors)

which troubleshooting is done mainly by checking if the soldering of the component is done properly.

Capacitor can be checked for shorts and resistors for value by means of an ohmmeter, but be aware in-circuit

measurements should be evaluated carefully.

Keep in mind that all measured voltages or RF levels depicted in the service manual are rough figures.

Especially RF levels vary because of different measuring equipment or different grounding of the probe used.

When using an RF probe, use a pair of metallic tweezers to connect the probe ground to the PWB ground as

close to the measurement point as possible. If measurements are performed in a product specific module

jig, then "GND" pads should be used for the probe ground.

Issue 1

All measurements with an RF coupler must be performed in an RF shielded environment,

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