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:
•
Juno D2800
•
Front End Module N7500
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.
Inductors: check for open circuits.
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.
•
A radio communication tester including RF generator and spectrum analyser, for example Rohde & Schwarz
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. Please refer to the list of Non-replaceable RF components.
Note: After the RF shielding can is removed (for measurement or repair), it must be replaced with
a new one and cannot be reused.
RM-497
RF troubleshooting
Issue 1 COMPANY CONFIDENTIAL Page 4 – 5
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