Nokia Customer Care
Abbreviations in fault finding charts
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 attenuated). 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).
Rx calibration done via Phoenix software is temperature dependent 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. In the following both, the name EGSM and EGSM900 will be used for the low
Issue 2.0 Mar/2005
Electro Static Discharge
General Packed Radio Service
High Speed Circuit Switched Data
Printed Wired Board
Phase Locked Loop
Ultra High Frequency
Voltage controlled oscillator
Very High Frequency
Copyright © 2005 Nokia Corporation.
TF4 Technical Information