Nokia RH-29 Series User manual

Nokia Customer Care
RH-29 Series Cellular Phones
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 1
Company Confidential
6b - RF Troubleshooting

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
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Company Confidential
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Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 1
Company Confidential
RF Troubleshooting.................................................................................................................................. 3
Abbreviations in troubleshooting charts .......................................................................................3
Introduction ...........................................................................................................................................5
RF Key component placement ..........................................................................................................6
RF measurement points ......................................................................................................................7
RF supply points................................................................................................................................. 7
Measurement points in the receiver ............................................................................................ 8
Measurement points in the transmitter...................................................................................... 9
Receiver................................................................................................................................................... 11
General instructions for RX troubleshooting ..............................................................................11
Measuring RX I/Q signals using RSSI reading ........................................................................ 11
Measuring RX performance using SNR measurement ......................................................... 13
Measuring front end power levels using spectrum analyzer ............................................. 14
Receiver RSSI readings from Phoenix ...........................................................................................16
Receiver troubleshooting .................................................................................................................18
GSM900 Transmitter............................................................................................................................ 19
General instructions for GSM900 TX troubleshooting .............................................................19
900 Tx troubleshooting flowchart ............................................................................................. 29
GSM1800 Transmitter......................................................................................................................... 30
General instructions for GSM1800 TX troubleshooting ..........................................................30
DCS1800 Tx troubleshooting flowchart .......................................................................................30
Path of the transmitted 1800 signal ............................................................................................30
The path of Mjoelner RF ASIC..................................................................................................... 31
The path of the PA.......................................................................................................................... 31
Antenna Switch............................................................................................................................... 31
Troubleshooting chart for GSM1800 transmitter .....................................................................33
RH-29 Synthesizer................................................................................................................................ 35
General instructions for synthesizer troubleshooting ..............................................................35
26 MHz reference oscillator (VCXO) .............................................................................................37
VCO .........................................................................................................................................................38
troubleshooting chart for PLL Synthesizer ..................................................................................38
PLL power supply ................................................................................................................................39
Loop Filter ......................................................................................................................................... 39
VCO and power supply .................................................................................................................. 39
26MHz Bluetooth buffer .............................................................................................................. 40
Antenna................................................................................................................................................... 40
Instructions for antenna troubleshooting ...................................................................................40
Phoenix Tuning...................................................................................................................................... 41
RF tuning after repairs ......................................................................................................................41
RX channel select filter calibration ...............................................................................................41
RX calibration (incl. VCXO Calibration) ........................................................................................42
EGSM900 and DCS1800 ............................................................................................................... 43
RX AGC limits ......................................................................................................................................47
RX band filter response compensation .........................................................................................47
EGSM900........................................................................................................................................... 47
DCS1800............................................................................................................................................ 50
TX I/Q tuning ........................................................................................................................................51
EGSM900........................................................................................................................................... 51

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DCS1800............................................................................................................................................ 56
TX power tuning ..................................................................................................................................62

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 1
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RF Troubleshooting
Abbreviations in troubleshooting charts
AFC Automatic Frequency Control
AGC Automatic Gain Control
ADC Analog Digital Converter
ASIC Application Specific Integrated Circuit
BB Base band
DC Direct Current
GSM Global System for Mobile Communication
HB High Band
LB Low Band
LNA Low Noise Amplifier
LO Local Oscillator
LPF Loop Filter
PA Power Amplifier
DCS Digital Cellular System
PLL Phase Locked Loop
PWB Printed Wired Board
RH-29 Project Type Designator
RF Radio Frequency
RX Receiver
SA Spectrum analyzer
TX Transmitter
UEM Universal Energy Management

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UHF Ultra High Frequency
UPP Universal Phone Processor
VCO Voltage-controlled oscillator
VCXO Voltage-controlled Crystal Oscillator
VHF Very High Frequency

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
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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.

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RF Key component placement
Figure 1: RF key component placement
Table 1: Key components
Reference
number Name Reference number Name
N601 Mjoelner RF ASIC
B601 26 MHz Xtal
Z602 GSM1800 RX SAW
Z604 900 RX SAW filter L801 Directional Coupler
Z701 900 TX SAW filter V801 Detector Diode
T701 GSM1800 TX Balun Z601 Antenna switch
V802 900 TX buffer N801 Power Amplifier

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RF measurement points
RF supply points
Figure 2: RF Supply points inside Mjoelner can
RF power supplies are generated in the UEM and can be measured either in the Mjoelner
can or in the baseband can. Arrows mark the measurement points inside the pictures.
G701 3.7 GHz VCO
T702 VCO Balun
Reference
number Name Reference number Name

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Measurement points in the receiver
Figure 3: Rx measurement points in antenna switch.
Figure 4: Rx measurement points at Rx SAW filters and Mjoelner RF ASIC
DCS1800 antenna
switch output
GSM900 antenna
switch output
Antenna
Switch input
DCS1800 SAW
Output/Mjoelner
Input
GSM900 SAW
Output/Mjoelner
Input
Z602
DCS RX
SAW Input
Z604
GSM RX
SAW Input