General Rf Troubleshooting - Nokia RM-4 Troubleshooting Instructions

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RM-4/RM-5

Troubleshooting Instructions

General RF Troubleshooting

Two types of measurements are used in the following. It will be specified if the measurement

type is "RF" or "LF".

•

RF measurements are done with a Spectrum Analyser and a high-

frequency 500 ohm passive probe, for example HP54006A. (Note that

when measuring with the 500 ohm probe the signal will be around 20 dB

attenuated. The values in the following will have these 20 dB subtracted

and represent the real value seen on the spectrum analyser).

Note that the testjig have some losses which must be taken into consideration when calibrating

the test system.

•

LF (Low frequency) and DC measurements should be done with a 10:1

probe and an oscilloscope. The probe used in the following is 10 Mohm,

8pF passive probe. If using another probe then bear in mind that the

voltages displayed may be slightly different.

Always make sure the measurement set-up is calibrated when measuring RF parameters on

the antenna pad. Remember to include the loss in the module repair jig when realigning the

phone.

Most RF semiconductors are static discharge sensitive. So, ESD protection must be ap-

plied during repair (ground straps and ESD soldering irons). Mjoelner and Bifrost is moisture

sensitive so parts must be pre-baked prior to soldering.

Apart from key-components described in this document there are a lot of discrete components

(resistors, inductors and capacitors) for which troubleshooting is done by checking if soldering

of the component is done properly and checking if the component is missing from PWB. Ca-

pacitors can be checked for short-circuiting and resistors for value by means of an ohmmeter,

but be aware in-circuit measurements should be evaluated carefully.

ISSUE 1 02/2004

COMPANY CONFIDENTIAL

CCS Technical Documentation

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Rm-5