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CCS Technical Documentation
General RF Troubleshooting
Two types of measurements are used in the following. It will be specified if the measure-
ment 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 fol-
lowing 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 10MW/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
applied 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 com-
ponents (resistors, inductors and capacitors) for which troubleshooting is done by check-
ing if soldering of the component is done properly and checking if the component is
missing from PWB. Capacitors 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.
In the following both the name EGSM and GSM850 will be used for the lower band and
both PCN and GSM1900 will be used for the upper band.
Issue 1 10/03
Company confidential
Nokia Corporation.
RH-18/36/38
Page 17
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Table of Contents
Troubleshooting
