Nokia 6600 Service Manual 06b nhl10 rf trouble

Customer Care Solutions

Technical Documentation

6(b) - RF T roubleshooting and

Manual T uning Guide

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CCS Technical Documentation RF Troubleshooting

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Table of Contents

Page No

Introduction ...................................................................................................................5

General troubleshooting ................................................................................................6

RF Key Component Placement ..................................................................................... 7

Receiver Troubleshooting ............................................................................................. 9

General Description .................................................................................................... 9

General Instructions for RX Troubleshooting .......................................................... 10

Measuring RX I/Q signals using RSSI ...................................................................10

Measuring RX performance using SNR measurement ........................................... 11

Measuring the RX module manually using Oscilloscope and Spectrum Analyzer 12

GSM900 ..................................................................................................................12

GSM1800 ................................................................................................................14

GSM1900 ................................................................................................................15

Measurement points in the Receiver ...................................................................... 17

Tuning of the RX Using Phoenix ................................................................................19

RX Channel Select Filter Calibration .......................................................................19

RX Calibration .......................................................................................................... 19

RX Band Filter Response Compensation .................................................................. 22

Transmitter Troubleshooting .......................................................................................25

General Description .................................................................................................. 25

Preparation for Fault Finding .................................................................................... 26

Fault-finding chart: TX-BB interface and control signals ...................................... 28

Fault-finding chart: RF side of transmitter .............................................................29

Transmitter Tuning ...................................................................................................... 30

Introduction ...............................................................................................................30

TX IQ Tuning ............................................................................................................ 30

TX Power Level Tuning ........................................................................................... 34

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RF Troubleshooting CCS Technical Documentation

Introduction

This document describes the troubleshooting and RF tuning of Nokia 6600 (NHL-10). In gen­eral, two types of measurements have to be performed during the troubleshooting and repair
of phones:

• RF measurements shall be done with a spectrum analyzer, either connected directly
to the RF connector of the board (“antenna point”), or used together with a high-fre­quency probe to measure RF signals at points along the TX or RX chain.

• LF (Low-Frequency) and DC measurements shall be done either with a multimeter, or
with an oscilloscope together with a 10:1 probe.

All tuning must be done with Phoenix Service Software, version A9 2003.15.2.25, or later.
Always make sure that the measurement set-up has been calibrated when measuring RF pa-

rameters 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).

Mjølner RF ASIC is moisture sensitive. Therefore, Mjølner RF ASIC must be pre-baked prior
to soldering.

RF calibration done via Phoenix software is temperature sensitive because of calibra­tion of 26MHz reference oscillator (VCXO). According to the Mjølner specification, ambient

temperature has to be in the range of 22 to 36

o

C.

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CCS Technical Documentation RF Troubleshooting

General troubleshooting

The first step of fault-finding should always be a visual inspection. Carefully inspect the RF area
using a microscope and look for cracks, solder bridges, dry joints, missing components, com­ponents that have partially come off and other anomalies. Capacitors can be checked to see
that they are not short-circuited, and inductors that they are not open circuits. Also check that
power supply lines are not short-circuited, i.e. not 0Ω to ground.

Instruments needed for trouble-shooting (minimum requirement):

• Oscilloscope

• Multimeter

• Spectrum analyzer (SA)

Note:
Use an attenuator at the spectrum analyzer input to ensure that the SA will not become damaged by
excessive input power from the phone. Check the spectrum analyzer for maximum allowable input
power.

• Power supply that can deliver at least 2Adc

• Nokia 6600 module jig (also called test jig)

• PC with Phoenix installed

Note:
In this text the following terms are used interchangeably:
GSM900 = EGSM900 = EGSM
GSM1800 = DCS band
GSM1900 = PCS band

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RF Troubleshooting CCS Technical Documentation

RF Key Component Placement

The following figure shows the key components of the RF section.

Figure 1: RF Key Components

shows key components of the RF section.

ᵱᵟᵵ

ᵐ

ᵥᵱ ᵫᵏᵖᵎᵎ

E-GSM900

ᵢᶓᵿᶊ

ᵡᶍᶓᶎᶊᶃᶐ

ᵟᶌᶒᶃᶌᶌᵿ

ᵱᶕᶇᶒᶁᶆ

ᵏ

ᵏᵑ

ᵠᶓᶄᶄᶃᶐ

ᵟᶋᶎᶊᶇᶄᶃ ᶐ

ᵮᶍᶕᶃᶐ

ᵟᶋᶎᶊᶇᶄᶃ ᶐ

ᵏᵎ

ᵱᵟᵵ

ᵑ

ᵥᵱ ᵫᵏᵗᵎᵎ

ᵱᵟᵵ

ᵒ

GSM1800

ᵣᵋ ᵥ ᵱᵫ ᵗᵎᵎ

ᵱᵟᵵ

ᵗ

ᵓ

ᵠᵟᵪᵳᵬ

ᵏᵒ

ᵡᶃ ᶊᶊᶓᶊᵿᶐ

ᵲᶐᵿᶌᶑᶁᶃᶇᶔᶃᶐ

ᵧᵡ

ᵔ

ᵠᶓᶄᶄᶃᶐ

ᵟᶋᶎᶊᶇᶄ ᶃᶐ

ᵏᵏ

ᵴᵡᵭ

ᵶᵲᵟᵪ

ᵕ

ᵖ

ᵠᶊᶓᶃᶒᶍᶍᶒᶆ

ᵲᶐᵿᶌᶑᶁᶃᶇᶔᶃᶐ

ᵏᵐ

Figure 2: RF Key Components

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CCS Technical Documentation RF Troubleshooting

Figure 3: RF Key Components

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RF Troubleshooting CCS Technical Documentation

Receiver Troubleshooting

General Description

Figure 4: Receiver Signal Path

The receiver is a direct conversion, triple-band linear receiver. NHL-10 uses Mjølner RFIC with
external VCO.

The received RF signal from the antenna/RF connector goes into the RF antenna switch where
the signal is fed to the E-GSM900, GSM1800 or GSM1900 path. For each band, a RX band­pass SAW filter with unbalanced input and balanced output follows. All blocks are specified as
50Ω single ended, only the SAW filter output to the Mjølner input is differentially matched to
LNA G
gain nominally 12 dB, the second one is about 30 dB below max. gain. The gain selection con­trol of the LNAs is done via the serial interface.

The differential RX signals are further amplified in the “pre-gain” stage and then mixed down to
baseband inside Mjølner using two Mixers with a 90° phase shift in the LO signal resulting in
an in- and quadrature phase paths. Local oscillator signal is generated with the external VCO.
The VCO signal is buffered and divided by 2 (DCS/PCS) or by 4 (EGSM). Accurate phasing is
generated in LO dividers.

The Rx BB chain incorporates AGC, channel select filter and DC compensation. The AGC is
adjusted in 6 dB steps in Mjølner. The DCN1 gain can be adjusted to +24/+18/+12/+6/0 dB.
The attenuator gain can step from 0/-6/-12/-18/-24/-30/-36/-42/-48dB. Other BB amplifiers have
a nominal summed gain of 58dB. The total dynamic range of AGC alone is 72dB. The 3
active channel filters in Mjølner defines the channel selectivity (flat response up to +/-90kHz
typical). Integrated base band filters are based on active RC filters with on-chip capacitors. The
baseband filters are distributed to following stages: BBAMP1, LPF1, LPF2. DC compensation
is split to DCN1 and DCN2. DCN1 is used to compensate DC offset from RF front-end imper-

. The LNAs are integrated in Mjølner and have two gain levels. The first one is max.

opt

rd

order

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CCS Technical Documentation RF Troubleshooting

fections. DCN2 centres the differential signal with respect to the common mode reference volt­age of 1.35V. Differential, filtered I/Q-signals are finally fed to the sigma-delta ADC’s in the
UEM. Further filtering in the digital domain occurs in the sinc decimation filter and DSP based
FIR filters

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

• Start Phoenix Service Software and establish a connection to the phone.

• Select File -> Scan Product Ctrl R.

• Wait until the phone software version is shown in the lower part of the screen.

• Select Testing -> RF controls.

• Select Band -> GSM900/GSM1800/GSM1900.

• Active unit -> RX.

• Operation mode -> Burst.

• RX/TX channel -> 37/700/661.

• Select RF Alt-M

Testing -> T
RSSI -> R

The set-up now looks like this:

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• Apply a signal with frequency of:
EGSM: 942.467MHz (channel 37 + 67.710KHz offset),
GSM1800: 1842.867MHz (channel 700 + 67.710KHz offset),
GSM1900: 1960.067MHz (channel 661 + 67.710KHz offset),
and a power level of –80dBm to the RF connector (remember to compensate for the
cable loss).

•In RSSI reading click Read now.

The resulting RSSI level should be –80dBm in each band.

Measuring RX performance using SNR measurement

Note: This measurement also provides an indication of the conducted sensitivity.

• Start Phoenix Service Software and establish a connection to the phone.

• Select File -> Scan Product Ctrl R.

• Wait until the phone software version is shown in the lower part of the screen.

• Select Testing -> RF controls.

• Select Band -> GSM900/GSM1800/GSM1900.

• Active unit -> RX.

• Operation mode -> Burst.

• RX/TX channel -> 37/700/661.

• Select Maintenance Alt-M

Testing -> T
SNR Measurement -> M

• Select Fast SNR.

• Choose the respective band (EGSM900, GSM1800, GSM1900).

• Press Measure.

• Follow the instructions for Signal generator set–up in the pop–up window.

• Press OK.

• Read the SNR result. The SNR should be: EGSM900: > 20dB

GSM1800: > 18dB
GSM1900: > 18dB

• Check the sensitivity value.

The set-up should now look as shown in the following figure. The icon also includes a pop-up
window for reference.

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Measuring the RX module manually using Oscilloscope and Spectrum Analyzer

Spectrum Analyzer level values depend on the probe type and should be validated using a
known good NHL-10 sample. The levels that are given here are measured using a high fre­quency probe.

Measuring with Oscilloscope on RXINN or RXQINN (J606 –608) and RXID or RXQD (J211 –
J212) is recommended only if RSSI reading does not provide enough information. No dedicat­ed test points exist for RX I/Q signals, however, they can be accessed by probing on a via hole
plating.

GSM900

• Start Phoenix Service Software and establish a connection to the phone.

• Select File -> Scan Product Ctrl R.

• Wait until the phone software version is shown in the lower part of the screen.

• Select Testing -> RF controls.

• Select Band -> GSM900.

• Active unit -> RX.

• Operation mode -> Continuous.

• RX/TX channel -> 7.

• AGC -> 9.

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RF Troubleshooting CCS Technical Documentation

The input freq/level of the signal generator is 942.467710MHz, -60dBm.

Figure 5: Fault finding chart for GSM900

Apply -60 dBm

942.4 MHz, offset

67.71 kHz

from generator to

antenna connector

YES

EGSM chain

functional

Check RSSI using

Phoenix Does it

match Sig Gen

Output level ?

NO

Replace UPP

YES

Is L.O running ?

YES

Probe J606 -609

RX I &Q Does

waveform look like

example given

earlier ?

YES

Probe J211 &J212

Is digital data

visable ?

visible

NO

Replace UEM

NO

Synthesiser Fault -

NO

Refer to

finding chart

Check RX/TX

switch at RX 900

Z601

Input -63 dBm

Output -63dbm

Spectrum analyzer

EGSM SAW filter

Z604

output -66 dBm

YES

Spectrum analyzer

Check signal after

inductors L606 and

L607

-66 dBm

YES

Oscilloscope

VRX 2.7 V on

Mjoelner

YES

NO NO

NO

NO

NO

Oscilloscope

check Vc1, Vc2,

Vc3 at Z601 signal

0V

Check RX/TX

switch

Check SAW filter

Check inductors

L606, L607

Check Base band

Z604

Check Mjoelner

YES

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Probed RX I/Q signals J606 - 609 with signal setting to 942.467710MHz, -60dBm. Note that
the display is the same for both GSM1800/1900 bands as well.

• Signal amplitude: 456mV

• DC offset: 1.36V

• Frequency: approx 67KHz

GSM1800

• Start Phoenix Service Software and establish a connection to the phone.

• Select File -> Scan Product Ctrl R.

• Wait until the phone software version is shown in the lower part of the screen.

• Select Testing -> RF controls.

• Select Band -> GSM1800.

• Active unit -> RX.

• Operation mode -> Continuous.

• RX/TX channel -> 700.

• AGC -> 9.

The input freq/level of the signal generator is 1842.867710MHz, -60dBm.

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RF Troubleshooting CCS Technical Documentation

Figure 6: Fault finding chart for GSM1800

Apply -60 dBm

1842.8 MHz, offset

67.71 kHz

from generator to

antenna connector

YES

EGSM chain

functional

Check RSSI using

Phoenix Does it

match Sig Gen

Output le vel ?

NO

Replace UPP

YES

Is L.O running ?

YES

Probe J606 -609

RX I &Q Does

waveform look like

example given

earlier ?

YES

Probe J211 &J212

Is digital data

visible

visable ?

NO

Replace UEM

NO

Synthesiser Fault -

NO

Refer to

finding chart

Check RX/TX

switch at RX 1800

Z601

Input -63 dBm

Output -65dBm

Spectrum analyzer

EGSM SAW filter

Z602

output -70 dBm

YES

Spectrum analyzer

Check signal after

inductors L603 and

L604

-73 dBm

YES

Oscilloscope

VRX 2.7 V on

Mjoelner

YES

NO NO

NO

NO

NO

Oscilloscope

check Vc1, Vc2,

Vc3 at Z601 signal

0V

Check RX/TX

switch

Check SAW filter

Check inductors

L603, L604

Check Base band

Z602

Check Mjoelner

YES

GSM1900

• Start Phoenix Service Software and establish a connection to the phone.

• Select File -> Scan Product Ctrl R.

• Wait until the phone software version is shown in the lower part of the screen.

• Select Testing -> RF controls.

• Select Band -> GSM1900.

• Active unit -> RX.

• Operation mode -> Continuous.

• RX/TX channel -> 661.

• AGC -> 9.

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CCS Technical Documentation RF Troubleshooting

The input freq/level of signal generator is 1960.067710MHz, -60dBm

Figure 7: Fault finding chart for GSM1900

Apply -60 dBm

1960 MHz, offset

67.71 kHz

from generator to

antenna connector

YES

EGSM chain

functional

Check RSSI using

Phoenix Does it
match Sig Gen

Output level ?

NO

Replace UPP

YES

Is L.O running ?

YES

Probe J606 -609

RX I &Q Does

waveform look like

example given

earlier ?

YES

Probe J211 &J212

Is digital data

visable ?

visible

NO

Replace UEM

NO

Synthesiser Fault -

NO

Refer to

finding chart

Check RX/TX

switch at RX 1900

Z601

Input -63 dBm

Output -65 dBm

Spectrum analyzer

EGSM SAW filter

Z603

output -70 dBm

YES

Spectrum analyzer

Check signal after

inductors L608 and

L609

-73 dBm

YES

Oscilloscope

VRX 2.7 V on

Mjoelner

YES

NO NO

NO

NO

NO

Oscilloscope

check Vc1, Vc2,

Vc3 at Z601 signal

Vc1, Vc3 =0V

Vc2=2.7V

Check RX/TX

switch

Check SAW filter

Check inductors

L608, L609

Check Base band

Z603

Check Mjoelner

YES

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Measurement points in the Receiver

Figure 8: Measurement points at the RX SAW filters –Z602, Z603, Z604

Figure 9: Measurement points for I/Q baseband signals

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Figure 10: Measurement points for RX I/Q digital signals

Figure 11: Measurement points at the Antenna switch

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Tuning of the RX Using Phoenix

RX Channel Select Filter Calibration

This calibration is calibrating the Baseband filter inside Mjølner ASIC. It is done by internally
measuring a prototype filter, for this reason the calibration is done once, not separately for all
three bands.

• Select Tuning -> RX Channel Select Filter Calibration.

• Press Tune.

RX channel select filter calibration is finished.

RX Calibration

The RX Calibration is used to determine the gain at different gain settings for the front-end and
the Mjølner ASIC and needs to be done in all three bands.

RX-calibration requires an external signal generator.

• Select Tuning -> RX calibration.

• Select band: GSM900.

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CCS Technical Documentation RF Troubleshooting

• Press Start.

• Follow the instructions in the pop–up window.

• Press OK.

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RF Troubleshooting CCS Technical Documentation

• Press Save & Continue.

• Press OK and continue.

For GSM1900 just repeat the same procedure as for GSM900/GSM1800. If the calibration is
OK, you should see “RX calibration was completed successfully” on the display.

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CCS Technical Documentation RF Troubleshooting

RX Band Filter Response Compensation

The Rx Band Filter Response Compensation has nine steps for each band.
The RF Band Filter Response Compensation requires an external signal generator.

• Select Tuning -> RX Band Filter Response Compensation.

• Select Manual.

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RF Troubleshooting CCS Technical Documentation

• Follow the instructions given in the following pop-up window . There are nine steps in
all.

• After completing the nine steps of calibration at nine frequencies, press Save & Con-
tinue.

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Repeat all steps as for GSM900 for the GSM1800 band. Follow all the instructions in the pop­up window. Repeat the procedure for GSM1900.

The tuning is completed.

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RF Troubleshooting CCS Technical Documentation

Transmitter Troubleshooting

General Description

A simple block diagram of the TX part of the phone is shown in the fo llowing figure. The voice
or data signals to be transmitted come from the UEME IC in the BB (Base Band) area, and go
to the Mjølner IC, where they are up-converted to RF. The TX signals going from UEME to Mjøl­ner are called the IQ signals, and consist of two balanced signals { TXIN, TXIP } and { TXQN,
TXQP }, i.e. a total of four signal lines. In addition to the IQ-signals, there are also control sig­nals going between BB and RF.

Figure 1: TX RF Block Diagram

BB-RF

Interface

Signals:

From UEME:

TXIQ

TXC

From UPP:

TXP

RFBUSCLK

RFBUSEN1

RFBUSDA

RESET

Mjølner

4

4

1/2

4

1/4

2

1800 / 1900MHz

900MHz

SAW

2

VPD_900

VPD_1800

V_BAT

VTXB_900 (BUFFER BIAS)

Discrete

TX buffer/amp

PA

Coupler Ant-Switch

VBD (DIODE BIAS)

Power
Detect

Power Loop Filter

DET

Synthesizer

LO

(LO=Local Oscillator)

The picture below shows the two shielding cans where the TX circuitry is located (the lid has
been removed). The shielding can on the right side contains BB-RF interface cir cuitry, the Mjøl­ner RF system IC, a SAW filter for the EGSM band, and a balun for the DCS/PCS band. The
shielding can on the left side contains the power amplifier (PA), the EGSM pre-amplifier, the
directional coupler, the power detector, and the Antenna Switch Module (ASM).

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CCS Technical Documentation RF Troubleshooting

Figure 2: GSM RF area

Directional

Coupler

Power

Detector

Circuit

Power

Amplifier

Preparation for Fault Finding

1 Place phone (mechanics removed) on module jig.
2 Connect the module jig to the PC via a DAU-9S cable.
3 Connect the module jig to the power supply (4.2V).

ASM

EGSM

Pre-Amp

DCS/PCS

Balun

Up-mixer bias

networks

(EGSM/DCS/PCS)

EGSM

SAW Filter

Mjolner

4 Connect the RF output to a spectrum analyzer or another measurement instru-

ment.

Use a 10dB attenuator at the input to spectrum analyzer to avoid damaging it.
5 Make sure the dongle is connected and start Phoenix.
6 In Phoenix, select File -> Open Product -> NHL-10 6600 Product Menu.
7 Select Testing -> RF Controls.
8 From the toolbar, set Operating Mode to Local.
9 Select band: GSM900, GSM1800 or GSM1900.
10 Set Operation Mode to Burst.
11 Set Active Unit to TX.
12 Set TX Data Type to All1.

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RF Troubleshooting CCS Technical Documentation

13 Set RX/TX Channel to 37 for GSM900, 700 for GSM1800 or 661 for GSM1900.
14 Set TX PA Mode to Free.
15 Set TX Power Level to 5 in GSM900, otherwise to 0.

Phoenix should now look as shown in the following figure.

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CCS Technical Documentation RF Troubleshooting

Fault-finding chart: TX-BB interface and control signals

Figure 3: Fault finding chart of BB-TX interface & some control signals

Start

Using a multimeter, check power supply lines to Mjolner:

Line

VR1a 4.75V J612

VR2 2.78V J613
VR3 2.78V J614 (J601)
VR5 2.78V J616
VR6 2.78V J617
VR7 2.78V J618

Using the oscilloscope, check TXC and TX IQ lines from UEME to Mjolner:

TXIOUTP R715 1.1Vdc 0.4Vp-p 67kHz
TXIOUTN R715 1.1Vdc 0.4Vp-p 67kHz

TXQOUTP R716 1.1Vdc 0.4Vp-p 67kHz

TXQOUTN R716 1.1Vdc 0.4Vp-p 67kHz

Using the oscilloscope, check TXP from UPP:

Using the oscilloscope, check control signals from Mjolner to ASM1:

1

Testpoint DC Voltage AC Voltage Frequency

Line

TXC J611 Depends on the power level 217Hz

Line
TXP J610 1.8V 217Hz

Testpoint GSM900 GSM1800 GSM1900 Period

Line
Cont1 R702 0V 2.7V 2.7V 4.615ms
Cont2 R703 0V 2.7V 2.7V 4.615ms
Cont3 R701 2.7V 0V 0V 4.615ms

=

Use Phoenix to set TX_Data_Type to 'Random'

Voltage Test Points

OK

OK

Testpoint Vpp Frequency

OK

OK

and to set TX Power Level to '5'

Not OK

Check UEME

(D190) in BB area

Not OK

Not OK

(D100) in BB area

Not OK

Check UEME

(D190) in BB area

Check UPP

Check serial

interface between

Mjolner & UPP

VR3

VR6

Mjolner output

bias network

VR7

VR2

TXIOUTP

TXIOUTN

VR5

VR1A

TXC

TXQOUTP

TXQOUTN

Cont1Cont2Cont3

TXP

Use the oscilloscope to check the voltage supply line to

the transistorized pre-amplifier: VTXB_900

Typical oscilloscope plots

of the four TXIQ-lines:

TXC-signal

EGSM900

channel = 37

PL = 5

Check serial

Not OK

interface between

Mjolner & UPP

Figure 4: Oscilloscope screen shots

zoom

1.1Vdc

~67kHz

TXP-signal

6

0.5Vpp

waveform for all 1's

4.615ms

VTXB_900

2.7V

Ctrl signals to ASM:

( DCS/PCS )

Cont1

Cont2

4.615ms

2.7V

4.615ms

4.

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Fault-finding chart: RF side of transmitter

In Phoenix select:
Active unit=TX, Operation Mode=Burst, TxPA Mode=Free,
TxData Type=Random, and for each band:
GSM900, channel=37, PL5
GSM1800, channel=700, PL0
GSM1900, channel=661, PL0

Measure power at RF connec tor:

GSM900: Power between 31 & 35dBm

GSM1800 & GSM1900: Power between 28 & 32dBm

NOK

Signal found?

Yes

Check power

control loop

OK

Correct signal at

ASM output?

No

Correct signal at

ASM input?

No

Correct signal at

directional coupler

input?

No

Correct signal at
power amplifier

input?

EGSM => check pre-amp & SAW

Check bias network at output of Mjolner IC

(Discrete components: R's, L's & C's)

Check fault finding chart of

No

DCS/PCS => check balun

OK

OK

TX-BB interface

OK

Mjolner broken?

Replace it & retune RF

Search for output signal with

No

500MHz span. Signal found

on incorrect frequency?

Yes

RF connector broken?

Yes

ASM broken?

Yes

Yes

directional coupler broken?

Yes

Check power

control loop

Spectrum analyzer screen shots

Measurements done at RF connector

OK

Transmitter is OK

OK

Check all

power levels

OK

power amplifier broken?

Tune TX power

synthesizer

4.615ms

OK

VPD_900 R818

Check power

control loop

Check power

control loop

Testpoint

Line
VBD R801
DET R802

Note:

2.7V

NOK NOK

Yes

Trouble-shoot

Using the oscilloscope, check power control loop signals
(Compare to oscilloscope screen plots shown below)

When using the SA to check if a signal is 'correct' at a certain

point (at input/output of ASM, directional coupler, PA, SAW-

filter, balun, etc.), the best way to do so is to compare with the

signal of a working sample of a phone. The reason for this is

that the level seen on the SA screen will vary depending on the

type of probe, the impedance of the measurement point, etc.

VBD: bias to pwr detector

EGSM

input

EGSM

output

PA

VPD_900

SAW

VPD_1800

DCS/PCS

PA

input

DCS/PCS

VTXB_900

(pre-amp bias)

Balun

output

ASM

DCS/PCS

input

ASM

TX

output

EGSM
output

PA

DCS/PCS

output

PA

ASM

EGSM

input

DET

VBD

Span = 3MHz

EGSM900

channel = 37

PL = 5

Span = 0Hz

DET: output of pwr detector

GSM900, PL=5

VPD_900: input voltage ctrl signal to PA

GSM900, PL=5

ISSUE 2 01/2004 COMPANY CONFIDENTIAL 29

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NHL-10

CCS Technical Documentation RF Troubleshooting

Transmitter Tuning

Introduction

In the transmitter, there are two kinds of tunings that can be performed. These are IQ-tuning
and power level tuning. In general, different repairs require different tunings. In order to decide
which tuning is necessary after a repair, it is important to understand well the functionality of
the repaired circuit. In general, it is recommended that if any TX component is changed, both
these tunings are done.

Note: All tunings are done in local mode using Phoenix to control the phone.

TX IQ Tuning

The tuning must be carried out in all three bands. In addition to Phoenix, a spectrum analyzer
(SA) is needed. Connect the SA to the RF connector of the module jig. The settings of the spec­trum analyzer will depend on the band to be tuned. The following table summarizes the settings
for each of the three bands.

Center frequency
Frequency span
Resolution

Bandwidth
Video Bandwidth
Sweep Time
Trace Type
Detector Type
Reference Level
Marker 1

Table 1: Spectrum Analyzer Settings

EGSM900 GSM1800 GSM1900

897.4MHz 1747.8MHz 1880MHz
300kHz 300kHz 300kHz
3kHz 3kHz 3kHz

3kHz 3kHz 3kHz
3 sec 3 sec 3 sec
Clear/Write Clear/Write Clear/Write
Max Peak Max Peak Max Peak
35dBm 35dBm 35dBm

897.33229 MHz 1747.73229 MHz 1879.93229 MHz

Marker 2
Marker 3

For this tuning, two windows of Phoenix must be open: (1) Testing -> RF Controls, and (2)
Tuning -> TX IQ Tuning, as seen in figures below.

30 COMPANY CONFIDENTIAL ISSUE 2 01/2004

897.4MHz 1747.8MHz 1880MHz

897.46771MHz 1747.86771MHz 1880.06771MHz

Copyright © 2003 Nokia. All Rights Reserved.

NHL-10
RF Troubleshooting CCS Technical Documentation

Figure 1: Phoenix set-up

Figure 2: Phoenix set-up

After opening the two before-mentioned windows, Phoenix should look as shown in the follow­ing figure.

ISSUE 2 01/2004 COMPANY CONFIDENTIAL 31

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CCS Technical Documentation RF Troubleshooting

Figure 3: Phoenix set-up

The following table summarises the settings of the RF control window for the IQ tuning of the
three bands.

Table 2: RF Control Window Settings

Band

TX Data

Type

TX Power

Level

RX/TX

Channel

GSM900 All 1 5 37
GSM1800 All 1 0 700
GSM1900 All 1 0 661

To start the IQ tuning, press Start in the IQ Tuning window.

32 COMPANY CONFIDENTIAL ISSUE 2 01/2004

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A

5

5

RF Troubleshooting CCS Technical Documentation

The spectrum analyzer screen should now look similar to that of the figure below (GSM900
case).

Figure 4: Spectrum analyzer screen shot when performing IQ tuning

Ref Lvl

Ref Lvl

35 dBm

35 dBm

3

27.5 dB Offset

30

20

10

0

-10

-20

-30

-40

-50

Marker 1 [T1]

33.35 dBm

897.33229000 MHz

1

RBW 3 kHz

VBW 3 kHz

SWT 3 s

2

RF Att 30 dB

Unit dBm

1 [T1] 33.35 dBm

897.33229000 MHz

2 [T1] -6.76 dBm

897.40000000 MHz

3 [T1] -10.74 dBm

897.46771000 MHz

3

A

1M

-60

-6

30 kHz/Center 897.4 MHz Span 300 kHz

Date: 14.JAN.2002 13:11:55

The purpose of this tuning is to reduce the frequency components at marker 2 (carrier leakage)
and marker 3 (+67kHz / upper sideband) as much as possible. Adjust the TXI DC Offset and
the TXQ DC Offset buttons in the TX IQ Tuning window so that the carrier level (marker 2)
reaches a minimum. After this adjustment, the carrier (marker 2) should be at least 40dB below
the lower side band (marker 1).

Next, use the Amplitude difference and the Phase difference buttons in the TX IQ Tuning
window to adjust the upper side band (marker 3) to a minimum. Now, marker 3 should also be
at least 40dB below marker 1.

At this point, the spectrum analyzer screen should look similar to that of the figure below.

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CCS Technical Documentation RF Troubleshooting

After reducing the amplitude of the frequency components at marker 2 and 3 to a minimum,
press Save & Continue. The EGSM tuning has now been completed.

Now, using the spectrum analyzer settings of Table 1, and the RF control settings of Table 2,
follow exactly the same procedure to perform IQ tuning in the GSM1800 and GSM1900 bands.

TX Power Level Tuning

This tuning is done separately in all three bands, and requires a spectrum analyzer to measure
the burst power of the GSM RF signal. When measuring the RF output (burst) power on a spec­trum analyzer, use the settings found in the following table:

34 COMPANY CONFIDENTIAL ISSUE 2 01/2004

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RF Troubleshooting CCS Technical Documentation

Table 3: Spectrum Analyzer Settings

EGSM900 GSM1800 GSM1900
Center frequency 897.4MHz 1747.8MHz 1880MHz
Frequency span Zero-span Zero-span Zero-span
Resolution Bandwidth 1MHz 1MHz 1MHz
Video Bandwidth 1MHz 1MHz 1MHz
Sweep Time 1ms 1ms 1ms
Trigger Type Video Video Video
Trace Type Clear/Write Clear/Write Clear/Write
Detector Type Max Peak Max Peak Max Peak

In Phoenix, select Tuning -> TX Power Level Tuning.

Figure 5: Phoenix menu select

Phoenix should now as shown in the figure below.

ISSUE 2 01/2004 COMPANY CONFIDENTIAL 35

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CCS Technical Documentation RF Troubleshooting

Figure 6: Phoenix power level tuning menu

Connect the module jig RF output to the measurement instrument. In the EGSM band the pow­er must be tuned in both high and low TX PA mode. In the two upper bands (GSM1800 and
GSM1900) there is only one mode.

For each band, tune the power by adjusting the coefficient in the Tx Power Level Tuning win­dow in Phoenix until the target level is reached (measured on the spectrum analyzer). Re mem­ber to take into account the external power loss, i.e. the loss of the cable and the external
attenuator at the spectrum analyzer input. The coefficient must be tuned for the base level and
other levels, marked with bold letters in Phoenix (GSM900: PL19/15/7/5, GSM1800/1900:
PL15, 11, 0).

When the tuning has been completed, press Save & Continue to save the new tuning values
into the phone memory.

The following figure shows the power level tuning at the GSM900 band.

36 COMPANY CONFIDENTIAL ISSUE 2 01/2004

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RF Troubleshooting CCS Technical Documentation

Figure 7: Phoenix screen shot

The next figure shows the spectrum analyzer screen shot associated with the above Phoenix
screen shot.

Figure 8: Spectrum analyzer screen short during power level tuning

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CCS Technical Documentation RF Troubleshooting

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38 COMPANY CONFIDENTIAL ISSUE 2 01/2004

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