Nokia 8208 Service Manual page 92

General RF troubleshooting
Introduction to RF troubleshooting
Most RF semiconductors are static discharge sensitive
ESD protection must be applied during repair (ground straps and ESD soldering irons).
Pre-baking
These parts are moisture sensitive and must be pre-baked prior to soldering:
RFIC: Qualcomm MSM6800A at U301
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PA: AWT6307R at U201,AWT6308R at U204
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Discrete components
In addition to the key-components, there are a number of discrete components (resistors, inductors and
capacitors) for which troubleshooting is done mainly by visual inspection .
Capacitors: check for short circuits.
Resistors: check value with an ohm meter.
Note: In-circuit measurements should be evaluated carefully
Measuring equipment
All measurements should be done using:
An oscilloscope for low frequency and DC measurements. Recommended probe: 10:1, 10Mohm//8pF.Title of
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the Document + Issue Number/Date of publication
A radio communication tester including RF generator and spectrum analyser, for example Rohde & Schwarz
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CMU200. (Alternatively a spectrum analyser and an RF generator can be used. Some tests in this guide are not
possible to perform if this solution is chosen).
Note: All measurements with an RF coupler should be performed in an RF-shielded environment because
nearby base stations can disturb sensitive receiver measurements. If there is no possibility to use RF
shielded environment, testing at frequencies of nearby base stations should be avoided.
Level of repair
The scope of this guideline is to enable repairs at key-component level. Some key-components are not
accessible, i.e. not replaceable.
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RF Troubleshooting
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