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
Page 2 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
[This page intentionally left blank.]

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

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 2 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
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
Company Confidential
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

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 2 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
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
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 3
Company Confidential
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.

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 4 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
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

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 5
Company Confidential
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

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

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 7
Company Confidential
Measurement points in the transmitter
Figure 5: Tx measurement points inside PA can
V802
900 Pre-
Amp
Z601
Antenna
Switch
N
801
Triple
Band PA
C815
Vbat Supply capacitor
C819
Vbat Supply capacitor
L801
Coupler
V801
Power Detector
L809
Vbat Supply inductor

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 8 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
Figure 6: Tx measurement points for TXC, TXP signals

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 9
Company Confidential
Receiver
General instructions for RX troubleshooting
Connect the phone to a PC with DAU-9S cable and dongle and follow the following
instructions:
Measuring RX I/Q signals using RSSI reading
Start Phoenix Service Software
Open the FBUS connection
Select Scan Product Ctrl-R
Wait until phone information shows in the window at the bottom of the screen.
Set operating mode to local mode
Phone information
Product Information
Software version

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 10 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
Select Testing Alt-S
RF Controls R
Wait until the RF Controls window pops up
Select Band GSM900 or GSM1800
Active unit RX
Operation mode Burst
RX/TX Channel 37 or 700
Select Testing Alt-S
RSSI reading G
The setup should now look like this:
Apply a signal with a frequency of
EGSM900: 942.467 MHz (channel 37 + 67.710kHz offset)
GSM1800: 1842.867 MHz (channel 700 +67.710kHz offset)
and a power level of -80dBm to the RF-connector (remember to compensate for cable
attenuation).
In RSSI reading click Start.

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 11
Company Confidential
The resulting RSSI level should be –80dBm in each band.
Measuring RX performance using SNR measurement
Start Phoenix Service Software
Open the FBUS connection
Select Scan Product Ctrl-R
Wait until phone information is shown in the lower window at the bottom of the screen.
Set operating mode to local mode
Select Testing Alt-S
RF Controls R
Wait until the RF Controls window pops up
Select Band GSM 900
Active unit RX
Operation mode Burst
RX/TX Channel 37
Select Testing Alt-S
SNR Measurement N
RSSI Reading

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 12 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
select Fast SNR Radio Button
The setup should now look like this:
Choose respective band (GSM900).
Press Start. A window pops up, e.g. for GSM900 band:
Connect an external signal generator to the RF connector of the phone and set the gen-
erator as told in the window, taking care for external cable losses.
Press ok and the window closes.
Read the SNR result. SNR should be: EGSM900 >20dB
GSM1800 >18dB
Measuring front end power levels using spectrum analyzer
Spectrum Analyzer (SA) level values depend on the probe type and should be vali-
dated using a good sample.

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 13
Company Confidential
The levels that are given here are measured using a resistive probe (50Ohm semi-rigid
cable).
Start Phoenix Service Software
Open the FBUS connection
Select Scan Product Ctrl-R
Wait until phone information shows in the lower right corner of the screen.
Set operating mode to local mode
Select Testing Alt-S
RF Controls R
Wait until the RF Controls window pops up
Select Band GSM 900 or DSC1800
Active unit RX
Operation mode Continuous
RX/TX Channel 37 or 700
Please refer to the troubleshooting chart for proper levels at different test points.

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 14 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
Receiver troubleshooting
Set up Phoenix as if doing RSSI measurements.
Ascertain which Rx band is faulty.
Refer to Rx troubleshooting flowchart.
Set signal generator frequency to 942.46771MHz for EGSM900 or 1847.86771MHz for
DCS1800.
Set signal generator amplitude to -60dBm.
Select Receive Band
For Testing.
Probe J606-609 for RX I & Q
Does Waveform
look like example?
Check RSSI using Phoenix.
Does it match Sig. Gen Output level?
Receiver is working
correctly.
Probe J211 &
J212. Is digital
data visible?
Replace UEMReplace UPP
Check SAW
Output / Mjoelner
Input for band. OK?
Check Mjoelner
Voltage Supplies &
RFBUS lines.
All OK?
Refer to BB
Fault Finding
Replace
Mjoelner
Check Antenna
Switch Test Point.
Signal OK?
Check PI Filter & SAW
Components. OK?
Replace all 3
Components
Replace
SAW Filter
Check Antenna
Switch Cont.
lines. Do they
match the results
in the table?
Replace
Antenna
Switch Check
L701, L702
L703. OK? Replace
Inductor
YES
NO
YES
NO
YES
NO
YES
YES
NO
NO
YES
NO
YES
NO
YES NO
NO
YES
Test With
Oscilloscope
Test With
Spectrum Analyzer End Action
KEY
Measure Vge at
same point. 0.2V?
Inspect PI filter &
SAW for S/c. S/C?
Rectify S/C
YES
NO
YES
NO
Inspect RF
Connector.
OK?
Replace RF
Connector
YES NO
Inspect /
Check
Is LO Running?
Refer to Synth.
Flow Chart.
NO
YES
YES
C650.
C650.
.
Probe J200 and J202, is
digital data visible?
OK? Replace
UEM.

Nokia Customer Care 6b - RF Troubleshooting
Company Confidential RH-29
Issue 1 05/2004 Copyright ©2004 Nokia Corporation Page 15
Company Confidential
GSM900 Transmitter
General instructions for GSM900 TX troubleshooting
Apply an RF-cable to the RF-connector to allow the transmitted signal to act normally.
The RF-cable should be connected to measurement equipment (GSM Test equipment,
Power meter, Spectrum Analyzer, or similar). Be sure to use at least a 10-dB attenuator,
otherwise the analyzer may be overloaded.
Connect the phone to a PC with DAU-9P cable and dongle and follow the following
instructions:
Connect the phone to a power supply (3.5... 4V).
Open Phoenix and select Fbus connection.
Select ‘File’ and ‘Scan Product’ from the pull down menus.
Select ‘Testing’, ‘RF controls’ from the pull down menu.
Chose Transmit Band for testing, Use the automatically selected channel.
Set Operation Mode to ‘Burst’.
Choose the Power level you want the phone to operate at.
Set spectrum analyzer center frequency, 897.4MHz for EGSM900 and 1747,8MHz for
DCS1800 and set Span to 1MHz.
Set Amplitude of spectrum analyzer reference level to one that you can clearly see the
transmit pulse according to the kind of test probe you are using.
Diagnose as per troubleshooting flowchart.
Note:Be careful when selecting the operation mode, if ‘Continuous’ is selected prolonged transmission
may damage the phone
TX Path of the transmitted GSM900 signal
For easy error tracing it is important to know the signal path of the GSM900 transmitter.
The components can be grouped into blocks and drawn as shown below. Note that the
following picture shows both GSM900 transmitter (bottom) and GSM1800 transmitter

RH-29 Company Confidential
6b - RF Troubleshooting Nokia Customer Care
Page 16 Copyright ©2004 Nokia Corporation Issue 1 05/2004
Company Confidential
(top).
GSM900 TX path of Mjoelner RF ASIC
The balanced TX signal is provided by the base band and is coming to the Mjoelner RF
ASIC. The TX paths of the Mjoelner RF ASIC include mainly two RF modulators for up-
conversion of the base band signals, one for GSM900 and one for GSM1800. The base
band signal is modulated with the LO signal corresponding to the wanted TX channel.
The GSM TX output of the Mjoelner RF ASIC is a balanced signal.
From the output of the Mjoelner RFASIC the signal is fed through the 900 TX SAW filter
(Balanced to single ended), the 900 MHz buffer, and a 5 dB pad to the PA input.
GSM900 TX path of the Power Amplifier (PA)
The PA GSM900 part has a minimum stable output power of app. 35 dBm. Voltage supply
is coming directly from the Battery connectors.
The GSM900 output is controlled by the power control loop. From the GSM900 output of
the PA the RF signal is fed through the directional coupler (one of the power control loop
components) to the antenna switch.
Antenna Switch (TX/RX switch)
The antenna Switch works as a diplexer for the RX and TX signals. Moreover, it sup-
presses the TX harmonics generated by the PA. The antenna switch is controlled by the
Mjoelner RF ASIC using the control signals Vcont1 and Vcont2. The following table