Introduction - Nokia RH-29 Series Manual

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Introduction

Two types of measurements have to be done for repair of the phone boards:
• RF measurements shall be done using a Spectrum Analyzer together
with a high-frequency probe. (Note, that signal will be significantly atten-
uated). Correct attenuation can be checked by using a "good" phone
board, for example.
• LF (Low frequency) and DC measurements shall be done with a an
oscilloscope together with an 10:1 probe.
Always make sure that the measurement set-up is calibrated when measuring RF param-
eters at the RF connector. Remember to include the correct losses in the module repair
jig and the connecting cable when realigning the phone.
Most RF semiconductors are static discharge sensitive. ESD protection must be taken
into account during repair (ground straps and ESD soldering irons).
Mjoelner RF ASIC is moisture sensitive. Therefore, Mjoelner RF ASIC must be pre-baked
prior to soldering.
Rx calibration done via Phoenix software is temperature sensitive because of cali-
bration of 26 MHz reference oscillator (VCXO). According to Mjoelner specification
ambient temperature has to be in a range from 22°C to 36°C.
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 ohm-meter, but be aware in-circuit measurements should be evaluated
carefully.
Issue 1 05/2004
Company Confidential
Copyright © 2004 Nokia Corporation
Company Confidential
RH-29
6b - RF Troubleshooting
Page 3