Nokia RM-94 Guide

Issue 1 04/2005 COMPANY CONFIDENTIAL
Copyright © 2005 Nokia. All Rights Reserved.
Nokia Customer Care
6(b) - RF Troubleshooting
Instructions

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Nokia Customer Care 6(b) - RF Troubleshooting Instructions
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RM-94
6(b) - RF Troubleshooting Instructions Nokia Customer Care
Table of Contents Page No
General Information on RF Troubleshooting ................................................... 5
Test environment............................................................................................... 5
Test conditions................................................................................................... 5
Receiver Verification and Troubleshooting...................................................... 7
General instructions for RX troubleshooting ...................................................... 7
Measuring RX I/Q signals using RSSI reading .................................................. 7
Measuring RX performance using SNR measurement .................................... 8
Measuring front-end power levels using spectrum analyzer ............................ 9
Measuring analogue RX I/Q signals using oscilloscope ................................ 10
Fault finding chart of the receiver..................................................................... 11
Transmitter ........................................................................................................ 18
General instructions for TX troubleshooting..................................................... 18
GSM900 transmitter......................................................................................... 18
General instructions for GSM900 TX troubleshooting ................................... 18
Fault finding chart for GSM900 transmitter .................................................... 20
GSM1800 transmitter....................................................................................... 22
General instructions for GSM1800 TX troubleshooting ................................. 22
Fault finding chart for GSM1800 transmitter .................................................. 24
GSM1900 transmitter....................................................................................... 26
General instructions for GSM1900 TX troubleshooting ................................. 26
Fault finding chart for GSM1900 transmitter .................................................. 28
Synthesizer........................................................................................................ 31
General instructions for synthesizer troubleshooting....................................... 31
Checking synthesizer operation....................................................................... 31
Fault finding chart for PLL synthesizer............................................................. 34
Frequency tables ............................................................................................. 36
GSM900 (including EGSM900) ...................................................................... 36
GSM1800 ....................................................................................................... 37
GSM1900 ....................................................................................................... 38
DC Supply Voltage Check ................................................................................ 39
Receiver test points ......................................................................................... 42
Transmitter test points ..................................................................................... 44
Synthesizer test points..................................................................................... 47

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Nokia Customer Care 6(b) - RF Troubleshooting Instructions
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RM-94
6(b) - RF Troubleshooting Nokia Customer Care
General Information on RF Troubleshooting
Notes:
Several bills of material (BOM): There are two different kinds of VCOs, VCTXOs, RF-PAs, SAW-
filters and Antenna Switches (ASM) assembled. They may only be replaced with the same type
as the original component (from the same manufacturer).
Phoenix version: In this document there are example measurements being depicted with pic-
tures of AMS-Phoenix,version A 2004.06.1.69. In later versionspictures of menus and windows
may look differently.
Layout version: The drawings of test points and component placement in this version of thedoc-
ument are taken from build B4.0 layout (1gqa_41a). If you use the document for newer layout
versions, make sure to use the corresponding assembly and test point drawings.
■ Test environment
It is assumed, that the phones are disassembled and tested with a repair jig MJ-22R.
The following measurements have to be done for repairing the phone boards:
•RF measurements shall be done using a spectrum analyzer together with a high-
frequency probe. Note that the signal will be significantly attenuated. Correct atten-
uation can be checked using a “good” phone board for example.
•LF (low frequency) and DC measurements shall be carried out with an oscillo-
scope together with a 10:1 probe.
• For receiver measurements, a signal generator specified for frequencies up to
2000 MHz is required. The signal generator is connected to the antenna port of the
repair jig.
Most of the radio communication testers, like CMU200, can be used as a signal gen-
erator, but make sure to have a continuous (CW) signal without modulation for align-
ment purposes.
•Transmitter output level measurements shall be done with a power meter
which is connected to the antenna port of the repair jig.
Always make sure that the measurement set-up is calibrated when measuring RF parameters
at the antenna port. Remember to put the correct losses of the module repair jig and the con-
necting cable in Phoenix or in the set-up programs of the RF generators when realigning the
phone.
Apart from key-components described in this document, there are a lot of discrete components
(resistors, inductors and capacitors) for which troubleshooting has to be done by checking its
proper soldering and complete assembly on the PWB. Capacitors and resistors can be
checked by means of an ohm-meter, but be aware in-circuit measurements should be evaluat-
ed carefully.
■ Test conditions
Rx tuning of the 26 MHz reference oscillator (VCTCXO) is temperature sensitive because
of the estimations of <AFC_value> and <AFC_slope>. According to the Production Test Spec-
ification DCS02294-EN-0.5, the ambient temperature has to be within a temperature range of
22°C to 28°C.

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MostRF semiconductors are staticdischarge sensitive. ESDprotection mustbetakeninto
account during repair (ground straps and ESD soldering irons).
The RF ASIC Helgo is moisture sensitive. Therefore, the ASIC must be pre-baked prior to
soldering.

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RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Receiver Verification and Troubleshooting
■ General instructions for RX troubleshooting
Connect the phone to a PC, which has Phoenix Service Software and a dongle installed, using
either
• repair jig and DAU-9S (RS232) cable or
• repair jig and XCS-4 cable via FPS-8 Flash Box or
• DAU-9T cable (RS232).
Connect the phone to a power supply (DC voltage: 3.6V, max. current: 3A) and an RF signal
generator. Switch the phone on.
Start Phoenix Service Software and open FBUS connection.
Select Scan Product Ctrl-R
and wait until the phone information (RM-94) is shown in the lower right corner of the screen.
Follow the instructions below.
■ Measuring RX I/Q signals using RSSI reading
Start Phoenix Service Software and open FBUS connection.
Select Scan Product Ctrl-R
Wait until the phone information is shown in the lower right corner of the screen.
Set the operating mode to local mode
Select Testing T
RF Controls F
Select Band GSM 900 or GSM1800 or GSM1900
Active unit RX
Operation mode Burst
RX/TX Channel 37 or 700 or 661
Select Testing T
RSSI reading R
In the RSSI Reading window, the <measuring mode> shall be set on Sum vector and the
<reading mode> on Continuous.
The set up should now look like this:

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(The example below shows a screen shot in GSM900!)
Make the following settings on your signal generator:
Frequencies:
• GSM 900: 942.46771 MHz (channel 37+ 67.710 kHz offset)
• GSM 1800: 842.86771 MHz (channel 700 + 67.710 kHz offset)
• GSM 1900: 1960.06771 MHz (channel 661+ 67.710 kHz offset)
RF power level:
• – 80 dBm @ the antenna connector of the phone/ test jig
(remembering to compensate for the cable and jig attenuation).
Click on <Read now> in RSSI reading.
The resulting RSSI level shall be – 80 dBm +/– 0.5 dB in each band.
Measuring RX performance using SNR measurement
Start Phoenix Service Software and open FBUS connection.
Select Scan Product Ctrl-R
Wait until the phone information is shown in the lower right corner of the screen.
Set operating mode to <local mode>.
Select Testing T
RF Controls F
Select Band GSM 900 or GSM1800 or GSM1900
Active unit RX

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RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Operation mode Burst
RX/TX Channel 37 or 700 or 661
Select Testing T
SNR Measurement M
Select Measuring mode Fast SNR (Radio Button)
Press Start
The window <Signal Measurement> pops up informing on frequency and power level of the
signal generator to be set. Follow the command <Turn ON the RF generator>.
Press <ok> and the window will close.
Read the SNR result from the window SNR Measurement. The value shall exceed:
• GSM 900: > 20 dB
• GSM 1800: > 18 dB
• GSM 1900: > 18 dB
The set up should now look like this:
(The example below shows a screen shot in GSM900!)
Choose the remaining GSM bands and measure accordingly the procedure described above.
Measuring front-end power levels using spectrum analyzer
Spectrum analyzer (SA) level values depend on the probe type and shall be verified by a prop-
erly working phone sample. The levels that are given in this document are measured with a re-
sistive probe (50 Ohm semi-rigid cable).
Start Phoenix Service Software and open FBUS connection.

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Select Scan Product Ctrl-R
Wait until the phone information is shown in the lower right corner of the screen.
Set <operating mode> to <local mode>.
Select Testing T
RF Controls F
Select Band GSM 900 or GSM1800 or GSM1900
Active unit RX
Operation mode Continuous
RX/TX Channel 37 or 700 or 661
Please refer to the fault finding chart and Appendix for proper levels at different test points.
Measuring analogue RX I/Q signals using oscilloscope
Measuring with an oscilloscope RX I and RX Q signals on the test points <RXI> respectively
<RXQ> is recommended only if the RSSI reading does not provide enough information. Input
level = -60dBm.
Start Phoenix Service Software and open FBUS connection.
Select Scan Product Ctrl-R
Wait until phone information is shown in the lower right corner of the screen.
Set operating mode to <local mode>.
Select Testing T
RF Controls F
Wait until the RF Controls window pops up.
Select Band GSM 900 or GSM1800 or GSM1900
Active unit RX
Operation mode Continuous
RX/TX Channel 37 or 700 or 661
AGC 10
The following picture should be displayed on an oscilloscope's screen if the receiver is working
properly:

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Copyright © 2005 Nokia. All Rights Reserved.
RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Signal amplitude 1.40Vpp
DC offset ª 1.28V as the offset is floating, switch to the operating mode
<Burst> in Phoenix and read the DC offset
Frequency 67kHz
■ Fault finding chart of the receiver
During fault finding, the calibration procedure is used to find out, whether all bands are affected
(error in common part of the Rx chain) or only one band (error in a Rx part of the failed band).
Take care not to save calibration values to the phone memory, which are out of limits.
Find the error first and repair it.
When a defective phone has been calibrated, a possible error in RX front-end might be
masked. In that case, one can get a reasonable RSSI reading, although the front-end shows
excessive losses. If it is not sure that incorrect re-calibration has been made, following steps
shall be carried out:
• Check if AGC calibration is within limits.
• Check if SNR reading is o.k.
Use an oscilloscope to check levels of “RXI” and “RXQ”.
The RF ASIC generates only single ended I and Q signals (RXI, RXQ). As the A/D converter
in UEM requires two differential signals, an artificial mid voltage is generated from VrefRF02.
The phone layout has dedicated test points for the analogue RX I and Q signals (J512, J513).
The BB part is used to measure those signals by means of RSSI reading. This works only if
correct calibration has been carried out in production.

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RSSIreading [dBm] = 20log(UBB/ULSB) - AGCcalibrated
In order to check the levels and frequencies of RF signals, the following probe can be used
(note that only the core lead contacts the test point, the shielding of the coaxial cable does not
contact GND during the measurement):
Connect this probe via a coaxial cable and a DC block to a spectrum analyzer. The DC block
is important to protect the spectrum analyzer from DC levels, which superpose the RF signal
at several test points.
If both RX and TX path seem to be faulty, it has to be checked if the synthesizer is working.

Issue 1 04/2005 COMPANY CONFIDENTIAL 13
Copyright © 2005 Nokia. All Rights Reserved.
RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Make sure that
Synthesizer is working
see
Synthesizer Fault
Finding Tree
Receiver
Fault Finding Tree
part 1
Rx chain is functional
and calibrated
Selected band is working and
calibrated.
A
re all 3 bands measured?
Yes
No
Yes
Signal Generator:
Level: –80dBm
Frequency: calculated from
Phoenix + 67.71kHz
No
Phoenix:
Phone: local mode
Open
RF Controls
:
Active Unit: Rx
Op. Mode: Burst
Rx/Tx channel: default (mid)
All 3 bands
Phoenix:
Open
RSSI reading
Check RSSI Level = -80dBm
Yes next bandNo
= To be done in all
three bands.
Execute Rx Calibration in selected
band, refer to chapter 9.2.1
A
re calibration results within limits?
Yes
No
A
re all 3 bands measured? No
Yes
Continue with single
band fault finding.
Yes
Receiver
Fault Finding Tree
part 2
Are all 3 bands defective? No
No
Check supply filter
components (C2233,
C7519, C7520) and UEM
Oscilloscope:
Check supply voltages of RF ASIC:
VR4 = 2.8V ? (TP: VR4)
Yes
Receiver
Fault Finding Tree
part 3
Oscilloscope:
Check supply voltages of RF ASIC:
VR6 = 2.8V ? (TP:VR6)
Yes
No
Check supply filter
components (C2231,
C7521) and UEM

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No
Check supply filter
components (R7511,
C7524) and UEM
Oscilloscope:
Check reference voltages of RF part:
VrefRF01 = 1.35V ?
(TP: VrefRF01*)
Yes
Receiver
Fault Finding Tree
part 4
Oscilloscope:
Check reference voltages of RF part:
VrefRF02 = 1.35V ?
(TPs: VrefRF02* and VrefRF02**)
Yes
No
Check supply filter
components (R2900,
R2901, C2900, C2901)
and UEM
Spectrum Analyzer:
1)
Check Rx/Tx Switch (Diplexer)
Depending on selected band, check level at TPs:
GSM900 output Rx1 Pref -1.5dB ?
GSM1800 output Rx2 Pref -2.0dB ?
GSM1900 output Rx3 Pref -2.5dB ?
Yes
Change Z7800
No
Note 1):
RF levels are dependent on RF probe and have to be validated
with a known good sample.
Receive
r
Fault Finding Tree
part 5
Signal Generator:
To be tuned that input power at spectrum
analyzer: –60dBm
(power at probe:
Pref = approx. -63 dBm)
Frequency: calculated from Phoenix
offset: 67.71kHz
Phoenix:
Phone: local mode
RF Controls
:
Active Unit: Rx
Op. Mode: Continuous
Rx/Tx channel: default (mid)
AGC: 14
Yes
BB error:
Check UPP
Oscilloscope:
RF-BB serial interface ok?
(TPs: RFBusData, RFBusClk, RFBusEna1)
Oscilloscope:
RX IQ levels ok (TPs: RXI, RXQ) ?
No Change RF
ASIC (Helgo)
Change RF
ASIC (Helgo)
Yes
Receiver
Fault Finding Tree
part 6
No

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RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Yes
Signal Generator:
Level: –92dBm
Frequency: calculated from Phoenix
Phoenix:
SNR measurement ok?
(SNR > 18.37dB)?
No
Front end is ok.
Receiver
Fault Finding Tree
part 7
Phoenix:
open
SNR Measurement
Meas. Mode: Fast SNR
Press
Measure
.
Single band fault finding
Select faulty band in Phoenix and continue measurements on dedicated Rx part.
Signal Generator:
Level: –60dBm
Frequency: calculated from Phoenix
offset: 67.71kHz
Phoenix:
Phone: local mode
RF Controls
:
Active Unit: Rx
Op. Mode: Continuous
Rx/Tx channel: default (mid)
AGC: 10
Continue with Rx Fault Finding part 6.
Spectrum Analyzer: 1)
Center Freq: calculated from Phoenix
RBW 20kHz
Change Rx SAW filters (Z7802,
Z7803) or component(s) of
matching network depending on
selected band
No
Yes
Note
1)
:
RF levels are dependent on RF probe and have to be validated
with a known good sample.
Receiver
Fault Finding Tree
part 8
Signal Generator:
To be tuned that input power at spectrum
analyser: –60dBm
power at probe: Pref =approx. -63dBm)
Frequency: calculated from Phoenix
offset: 67.71kHz
Phoenix:
Phone: local mode
RF Controls
:
Active Unit: Rx
Op. Mode: Continuous
Rx/Tx channel: default (mid)
AGC: 14
Check Rx SAW filter and matching
network of selected band:
GSM900 TPs: INM_G_RX / INP_G_RX
both output levels > Pref -3.5dB ?
GSM1800 TPs: INM_D_RX / INP_D_RX
both output levels > Pref -6dB ?

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No
No
Check supply
filter components
around V7800
and RF ASIC
If selected band = GSM1900
Oscilloscope:
Check voltages for V7800:
Voltage at C7802 = 2.5V ?
Volta
g
e at C7800 = 0V ?
Yes
Spectrum Analyzer: 1)
Check external LNA V7800:
TP: OUT-V7800
Output signal > Pref +14dB
No
Yes
Receiver
Fault Finding Tree
part 9
Note
1)
:
RF levels are dependent on RF probe and have to be validated
with a known good sample.
RF ASIC N7500 seems to be
defective. Exchange N7500.
Spectrum Analyzer:
1)
Check balun T7800 and matching network:
TPs: INM_P_RX / INP_P_RX
Both output signals > Pref +12dB
No
Yes
No
Yes
Yes
Change T7800
Yes
Spectrum Analyzer: 1)
Check SAW filter Z7801:
TP: OUT-Z7801
Output signal > Pref - 3.5dB
Change Z7801
No

Issue 1 04/2005 COMPANY CONFIDENTIAL 17
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RM-94
6(b) - RF Troubleshooting Nokia Customer Care
Signal Generator:
Level: –60dBm
Frequency: 942.4MHz
Offset: 67.71kHz
Oscilloscope:
RF-BB filter signals ok?
TPs: CM_F_Q & CM_F_I
CM_DTOS_Q & CM_DTOS_I
Yes
Re-solder capacitor array C7523
Receiver
Fault Finding Tree
part 10
Channel select filter fault finding
Continue measurement only when channel select filter calibration failed
Change RF
ASIC (Helgo)
Phoenix:
Phone: local mode
RF Controls
:
Active Unit: Rx
Op. Mode: Burst
Rx/Tx channel: default (mid)
AGC: 14
NoYes
No
Repair finished
Re-calibrate
Channel Select Filter
Calibration ok ?
Make sure that Synthesizer is
working and supply voltages of
RF ASIC are ok
Make following tunings/calibrations
x Tx power level tuning
x Tx IQ tuning
x Rx calibration
x Rx Band Filter Response Calib.

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Transmitter
■ General instructions for TX troubleshooting
Connect the phone to a PC, which has Phoenix Service Software and a dongle installed, using
either
• repair jig and DAU-9S (RS232) cable or
• repair jig and XCS-4 cable via FPS-8 Flash Box or
• DAU-9T cable (RS232)
Connect the phone to a power supply (DC voltage of 3.6V) and switch the phone on. The value
of the DC voltage of 3.6V at the phone battery connector is crucial.
Connect an RF cable between the test jig and the measurement equipment (GSM test equip-
ment, power meter, spectrum analyzer, or similar).
Make use of an adequate attenuator at the input of your measurement equipment (10dB to
20dB are recommended for a spectrum analyzer or a power meter). Additionally, a DC block is
recommended. Assure not to overload or destroy the equipment.
It is strongly recommended to use TXP as external trigger for all TX tunings.External triggering
gives the following advantages:
• trigger for spectrum analyzer (gated sweep)
• trigger for oscilloscope
• trigger for power meter (avoid exchanging of attenuator and getting better accu-
racy in power measurements)
Start Phoenix Service Software and open FBUS connection:
Select Scan Product Ctrl-R
and wait until the phone information is shown in the lower right corner of the screen.
Follow the instructions in the chapters below.
■ GSM900 transmitter
General instructions for GSM900 TX troubleshooting
Start the preparations as described in chapter “General instructions for TX troubleshooting”.
GMSK
Set operating mode to local mode.
Select Testing RF Controls
Wait until the RF Controls window pops up
Select Band GSM 900
Active unit TX

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Operation mode Burst
RX/TX Channel 37
TX Power Level 10
TX Data Type Random
Edge Off
The setup should now look like this:
Now the measurement equipment should detect the following output signal of the phone:
Pout = +23dBm @ 897.4 MHz
If this is not the case, go to the GMSK fault finding chart for the GSM900 transmitter.
EDGE
Set operating mode to local mode.
Select Testing RF Controls
Wait until the RF Controls window pops up.
Select Band GSM 900
Active unit TX
Operation mode Burst

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RX/TX Channel 37
TX Power Level 10
TX Data Type All1
Edge On
The setup should now look like this:
Now the measurement equipment should detect the following output signal of the phone:
Pout = +24.5 dBm @ 897.4 MHz
If this is not the case, go to the EDGE fault finding chart for GSM900 transmitter.
Fault finding chart for GSM900 transmitter
In the following, it is assumed that the TXP signal is used as trigger signal. For that, a TXP test
point is provided.