General instructions for cellular RF troubleshooting
Most RF semiconductors are static sensitive
ESD protection must be applied during repair (ground straps and ESD soldering irons).
Measuring equipment
All measurements should be done using Willtek/Aeroflex 440x/3100, Rohde & Schwarz CMU-200 or CMW-500
radio communication tester.
Note:
A mobile phone WCDMA transmitter should never be tested with full TX power (permitted
only if measurements and tests are performed in an RF-shielded environment). Even low power
WCDMA transmitters may disturb nearby WCDMA networks and cause problems to 3G cellular
communication in a wide area.
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 an RF-shielded environment, testing at frequencies of nearby base stations should be avoided.
Note:
All communication test set screen dumps are from CMU-200. Other testers are different.
RF auto tune
RF auto tune is not available for WP8 devices.
RF shield cans
All RF shield cans are solid and should not be opened in service centers.
Level of repair
The scope of this guideline is to verify functionality of the cellular RF block as well as possible without
removing RF shields.
RM-824; RM-825; RM-826
Cellular RF troubleshooting
Issue 2
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