Nokia N-GageQD Service Manual 6b rh29 rf troubleshooting

Nokia Customer Care

RH-29 Series Cellular Phones

6b - RF Troubleshooting

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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 ...........................................................................................................

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

....... 39

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DCS1800............................................................................................................................................ 56

TX power tuning ..................................................................................................................................62

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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

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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 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 parameters 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 calibration 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 components (resistors, inductors and capacitors) for which troubleshooting is done by checking 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

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

Name

Reference number

Name

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Reference number

G701 3.7 GHz VCO

T702 VCO Balun

Name

RF measurement points

RF supply points

Reference number

Name

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.

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Measurement points in the receiver

Figure 3: Rx measurement points in antenna switch.

GSM900 antenna switch output

DCS1800 antenna switch output

Antenna Switch input

Figure 4: Rx measurement points at Rx SAW filters and Mjoelner RF ASIC

DCS1800 SAW Output/Mjoelner Input

GSM900 SAW Output/Mjoelner Input

Z602 DCS RX SAW Input

Z604 GSM RX SAW Input

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Measurement points in the transmitter

Figure 5: Tx measurement points inside PA can

V802 900 PreAmp

801 Triple Band PA

V801 Power Detector

C815 Vbat Supply capacitor

L809 Vbat Supply inductor

L801 Coupler

Z601 Antenna

C819 Vbat Supply capacitor

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Figure 6: Tx measurement points for TXC, TXP signals

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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

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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.

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

RSSI Reading

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

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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 generator 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 validated using a good sample.

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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.

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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.

Check Antenna Switch Cont. lines. Do they match the results

in the table?

YES NO

Inspect RF

C650.

Connector. OK?

YES NO

Replace Antenna

C650.

Switch

Replace RF Connector

Check L701, L702

OK?

L703. OK?

YES

Check Antenna Switch Test Point. Signal OK?

YES

Check PI Filter & SAW Components. OK?

YES

Replace SAW Filter

Replace all 3 Components

Replace Inductor

KEY

Test With Spectrum Analyzer

Check SAW

Output / Mjoelner Input for band. OK?

Measure Vge at same point. 0.2V?

Inspect PI filter & SAW for S/c. S/C?

YES

Rectify S/C

Test With Oscilloscope

Refer to Synth. Flow Chart.

YES

Check Mjoelner Voltage Supplies & RFBUS lines. All OK?

Check RSSI using Phoenix. Does it match Sig. Gen Output level?

Is LO Running?

Probe J606-609 for RX I & Q

Does Waveform

YES

look like example?

YES

Probe J211 &

Probe J200 and J202, is

J212. Is digital data visible?

digital data visible?

YES

Replace UEMReplace UPP

YES

Replace Mjoelner

Inspect / Check

Replace

Refer to BB

UEM.

Fault Finding

End Action

YES

Receiver is working correctly.

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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

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(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 upconversion 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 suppresses 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

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shows the possible different states.

Vcont1 [Volt]

0 0 X

0 2.7 X

2.7 0 X

Vcont2 [Volt]

900 Rx DCS Rx 900 Tx DCS Tx

Phone information Product Information Software version

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Figure 7: TX Digital I & Q Test Points

J203 TXQD

J202 TXID

Figure 8: TX Digital I & Q Data, J202 and J203

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+ 51 hidden pages

Nokia N-GageQD Service Manual 6b rh29 rf troubleshooting

Specifications and Main Features

Frequently Asked Questions

User Manual

6b - RF Troubleshooting

RF Troubleshooting

Abbreviations in troubleshooting charts

Introduction

RF Key component placement

RF measurement points

RF supply points

Measurement points in the receiver

Measurement points in the transmitter

Receiver

General instructions for RX troubleshooting

Measuring RX I/Q signals using RSSI reading

Measuring RX performance using SNR measurement

Measuring front end power levels using spectrum analyzer

Receiver troubleshooting

GSM900 Transmitter

General instructions for GSM900 TX troubleshooting

TX Path of the transmitted GSM900 signal

GSM900 TX path of Mjoelner RF ASIC

GSM900 TX path of the Power Amplifier (PA)

Antenna Switch (TX/RX switch)