Nokia 6670, 7610 Service Manual 06b rh51 rf trouble

Nokia Customer Care

RH-51/52, RH-67/68 Series Cellular Phones

6(b) - RF Troubleshooting and

Manual Tuning Guide

Company Confidential

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

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Company Confidential RH-51/52, RH-67/68

Nokia Customer Care 6(b) - RF Troubleshooting

Table of contents

Page No

Introduction ...............................................................................................................................................7

General troubleshooting ..................................................................................................................... 7

RF key component placement...............................................................................................................9

Receiver troubleshooting......................................................................................................................10

General description ............................................................................................................................10

General instructions for RX troubleshooting ..............................................................................12

Measuring RX I/Q signals using RSSI..........................................................................................12

Measuring RX performance using SNR measurement ...........................................................14

Measuring the RX module manually using oscilloscope and spectrum analyzer...........15

GSM 900/850.....................................................................................................................................15

GSM1800 ............................................................................................................................................17

GSM1900 ............................................................................................................................................19

Measurement points in the receiver ...........................................................................................21

Tuning RX using Phoenix......................................................................................................................23

RX channel select filter calibration ...............................................................................................23

RX calibration ....................................................................................................................................23

RX band filter response compensation.......................................................................................25

Transmitter troubleshooting................................................................................................................27

General description ............................................................................................................................27

Preparation for troubleshooting .....................................................................................................28

Fault-finding chart: TX-BB interface and control signals.....................................................30

Fault-finding chart: RF side of transmitter...............................................................................31

Transmitter tuning..................................................................................................................................34

TX IQ tuning .........................................................................................................................................34

TX power level tuning ........................................................................................................................39

Synthesizer troubleshooting................................................................................................................43

General description ............................................................................................................................43

Assumption ...........................................................................................................................................45

Preparation for troubleshooting .....................................................................................................46

Measuring the synthesizer manually using spectrum analyzer ............................................47

Troubelshooting chart for synthesizer ..........................................................................................47

Bluetooth troubleshooting...................................................................................................................49

Bluetooth component placement ..................................................................................................49

Bluetooth settings for Phoenix ................................................................................................

Bluetooth troubleshooting diagram ..............................................................................................52

.......49

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Nokia Customer Care 6(b) - RF Troubleshooting

List of figures

Page No

Fig 1 RF key components.........................................................................................................................9

Fig 2 RF key components.........................................................................................................................9

Fig 3 Receiver signal path .................................................................................................................... 10

Fig 4 Troubleshooting chart for EGSM900 (GSM850).................................................................. 16

Fig 5 Probed RX I/Q signals J827, 828.............................................................................................. 17

Fig 6 Troubleshooting chart for GSM1800...................................................................................... 18

Fig 7 Troubleshooting chart for GSM1900...................................................................................... 20

Fig 8 Measurement points at RX frontend - part 1...................................................................... 21

Fig 9 Measurement points at RX frontend - part 2...................................................................... 21

Fig 10 Measurement points at baseband IQ................................................................................... 22

Fig 11 Measurement points at digital IQ......................................................................................... 22

Fig 12 TX RF block diagram.................................................................................................................. 27

Fig 13 Troubleshooting chart of TX-BB interface and control signals .................................... 30

Fig 14 Oscilloscope screen shots........................................................................................................ 30

Fig 15 Troubleshooting chart of RF side of transmitter............................................................... 31

Fig 16 Phoenix set-up (RF Controls menu)......................................................................................35

Fig 17 Phoenix set-up (Tx IQ Tuning menu).................................................................................... 35

Fig 18 Phoenix set-up (Tx IQ Tuning windows).............................................................................. 36

Fig 19 Spectrum analyzer screen shot when performing IQ tuning, part 1........................... 37

Fig 20 Spectrum analyzer screen shot when performing IQ tuning, part 2........................... 38

Fig 21 Phoenix menu select (Tx Power Level Tuning menu)....................................................... 39

Fig 22 Phoenix Power Level Tuning menu .......................................................................................40

Fig 23 Phoenix screen shot (Tx Power Level Tuning).................................................................... 41

Fig 24 Spectrum analyzer screen shot during power level tuning ........................................... 42

Fig 25 Synthesizer block diagram ...................................................................................................... 43

Fig 26 RF key component. .................................................................................................................... 45

Fig 27 Synthesizer key components without shielding frame ...................................................45

Fig 28 Preparation for troubleshooting using Phoenix – RF control setup............................ 46

Fig 29 Troubleshooting chart for synthesizer .................................................................................47

Fig 30 Measurement points for synthesizer. Layout shows HELGO/VCO compartment..... 48

Fig 31 Measurement points for synthesizer. Layout shows UEME compartment................ 48

Fig 32 RH-51/52, RH-67/68 Bluetooth component placement ................................................49

Fig 33 Phoenix settings for Bluetooth troubleshooting............................................................... 51

Fig 34 Bluetooth troubleshooting flowchart .................................................................................. 52

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Company Confidential RH-51/52, RH-67/68

Nokia Customer Care 6(b) - RF Troubleshooting

Introduction

This document describes troubleshooting and RF tuning of RH-51/52, RH-67/68. In general, two types of measurements have to be done during troubleshooting and repair of phones:

• RF measurements shall be done with a spectrum analyzer, either connected directly to the RF connector of the RF adapter board SA-29, or used together with a highfrequency 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 2004.32.2.58 or later.

Always make sure that the measurement set-up has been 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).

Helgo RF ASIC is moisture sensitive. Therefore, Helgo RF ASIC must be pre-baked prior to soldering unless it is stored in a sealed moisture barrier bag.

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

the ambient temperature has to be in the range of 22 to 36°C.

General troubleshooting

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

The first step of fault-finding should always be a visual inspection. Carefully inspect the RF area using a microscope and look for solder bridges, missing components, short circuits, 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 troubleshooting (minimum requirement):

• oscilloscope

• multimeter

• spectrum analyzer (SA)

Note: Always 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.

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

For example, when transmitting in the EGSM band at max power level, the output power will be around +33dBm. By using a 10dB attenuator the actual input to the SA will then be +23dBm. Also adjust the internal attenuator so that the transmitted signal is reduced to less than around -10dBm in order to avoid saturation of SA input stage.

• power supply that can deliver at least 2Adc

• Nokia MJ-25 module jig (also called test jig)

•RF adapter SA-29

• PC with Phoenix installed

• PKD-1 deskey dongle for Phoenix

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Nokia Customer Care 6(b) - RF Troubleshooting

RF key component placement

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

Figure 1: RF key components

Z800

Antenna

Switch

N700

Power

Amplifer

Z801

SAW

EGSM900/GSM850

Figure 2: RF key components

V800

LNA

Z191

SAW

GSM1900

GSM1800

13 14

T800

BALUN

Z802

SAW

Z803

SAW

Z700

SAW

T700

BALUN

Z192

BALUN

G500

VCO

N500

Cellular

Transceiver

ASIC

HELGO

G501

TCXO

D190

Bluetooth

Transceiver

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

Receiver troubleshooting

General description

Figure 3: Receiver signal path

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Nokia Customer Care 6(b) - RF Troubleshooting

Each receiver path is a direct conversion linear receiver. From the antenna, the received RF signal is fed to a front end module where a diplexer first divides the signal to two separate paths according to the band of operation: either lower, GSM850/EGSM900 or upper, GSM1800/1900 path. At each of the paths follows a pin-diode switch, which is used to select either a receive- or transmit mode. At the upper band in the receive mode either GSM1800 or 1900 path is further selected by another pin-diode switch. The selections are controlled by Helgo, which obtains the mode/band and timing information through the RFBus. After the switches an external bandpass filter follows each receiver paths. Thereafter, the signal is fed to the LNA's. GSM850/EGSM900 and GSM1800 LNA's are integrated in Helgo, while the GSM1900 LNA is a discrete component placed between SAW filter and balun. In GSM1900, the amplified signal is fed to a pre-gain stage of the mixer. GSM850/EGSM900 and GSM1800 LNA's are connected directly to the pregain stages. The pregain stages as well as all the following receiver blocks are integrated in Helgo. The LNA's have three gain levels. The first one is the maximum gain, the second one is about 30 dB below the maximum, and the last one is the off state.

After the pregain stages there are demodulator mixers at each signal path to convert the RF signal directly down to baseband I and Q signals. Local oscillator signals for the mixers are generated by an external VCO. The frequency is divided by two in GSM1800 and GSM1900 and by four in GSM850/EGSM900. Those frequency dividers are integrated in Helgo and in addition to the division they also provide accurate phase shifting by 90 degrees which is needed for the demodulator mixers.

The demodulator output signals are all differential. After the demodulators there are amplifiers called DtoS (differential to single ended) which convert the differential signals to single ended. Before that, they combine the signals from the three demodulators to a single path which means that from the output of the demodulators to the baseband interface are just two signal paths (I and Q), which are common to all the frequency bands of operation. In addition, the DtoS amplifiers perform the first part of the channel filtering and AGC (automatic gain control). They have two gain stages, the first one with a constant gain of 12 dB and -3 dB bandwidth of 85 kHz and the second one with a switchable gain of ±6 dB. The filters in the DtoS blocks are active RC filters. The rest of the analog channel filtering is provided by blocks called BIQUAD which include modified Sallen-Key biquad filters.

After the DtoS and BIQUAD blocks, there is another AGC-amplifier which provides a gain control range of 42 dB in 6 dB steps. The correlation between the gain steps and the absolute received power levels is found by a calibration routine in the production for each assembled phone.

In addition to the AGC steps, the last AGC stage also performs the real time DC offset compensation, which is needed in a direct conversion receiver to cancel out the effect of the local oscillator leakage. DC offset compensation is performed during an operation called DCN1. DCN1 is carried out by charging capacitors at the input of the last AGC stages to a voltage, which causes a zero DC offset. To improve the accuracy a DC level alignment possibility has been added to Helgo.

After the last AGC stages the single ended and filtered I- and Q-signals are fed to the RX

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

ADCs. The maximum peak-to-peak voltage swing for the ADCs is 1.45 V.

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 connection to the phone

Select File -> Open Product

RH-51, -52, -67 or -68

Select Testing ->RF controls

Select Band ->GSM850 / GSM900 / GSM1800 / GSM1900

Active unit ->RX

Operation mode ->Burst

RX/TX channel -> EGSM900: 37

GSM850: 190

GSM1800: 700

GSM1900: 661

Select

Testing (T)

RSSI Reading (R)

Set –up now looks like this:

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Nokia Customer Care 6(b) - RF Troubleshooting

Apply a signal with frequency of

EGSM900:942.4677MHz (channel 37 + 67.7KHz offset)

GSM850: 881.667MHz (channel 190 + 67.7KHz offset)

GSM1800:1842.8677MHz (channel 700 + 67.7KHz offset)

GSM1900:1960.0677MHz (channel 661 + 67.7KHz offset)

and a power level of –80dBm to the RF connector (remember to compensate for cable loss).

In RSSI reading, click Read now.

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

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

Measuring RX performance using SNR measurement

Note: This measurements also provides an indication of the conducted sensitivity

Start Phoenix Service Software and establish connection to the phone

Select File ->Open Product

RH-51, -52, -67 or -68

Select Testing ->RF controls

Select Band ->GSM850 / GSM900 / GSM1800 / GSM1900

Active unit ->RX

Operation mode ->Burst

RX/TX channel -> EGSM900: 37

GSM850: 190

GSM1800: 700

GSM1900: 661

Select Testing (T)

SNR Measurement (M)

select Both

Choose respective band (GSM850, EGSM900, GSM1800, GSM1900).

Press Start.

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

Press OK.

Read the SNR result. SNR should be: >18dB.

Check the sensitivity value.

The set–up should now look like this; the icon also includes pop–up window for reference:

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Nokia Customer Care 6(b) - RF Troubleshooting

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 sample. The levels that are given here are measured using a high frequency probe.

Measuring with oscilloscope at test point RXI (J827) or RXQ (J828) ) and RXID (J261) or RXQD (J262) is recommended only if RSSI reading does not provide enough information.

GSM 900/850

Start Phoenix Service Software and establish connection to the phone

Select File Open Product

RH-51, -52, -67 or -68

Select Testing RF controls

Select Band GSM900 (GSM850)

Active unit RX

Operation mode Continuous *

RX/TX channel 37 (190 for GSM850)

AGC 12

RH-51/52, RH-67/68 Company Confidential 6(b) - RF Troubleshooting Nokia Customer Care

Input freq/level of signal generator is 942.4677MHz, -60dBm

(881.6677MHz for GSM850)

Note: Because DC compensation doesn’t work during continuous mode, DC offset level at RXI and RXQ will gradually shift from the optimized level. To have most reliable result, it is highly advisable to set operation mode from burst to continuous just before measuring values and complete measurement within no longer than 30 seconds.

Figure 4: Troubleshooting chart for EGSM900 (GSM850)

EGSM900 (GSM850)

chain functional

Replace UPP

D370

942.4677 MHz (881.6677 MHz for GSM850)

YES

Apply -60 dBm

from generator to antenna connector

Check RSSI using

Phoenix Does it

match Sig Gen

Output level ?

Is L.O running at

3769.6MHz

(3526.4MHz for

GSM850?

YES

Probe J827, 828

RX I &Q Does waveform

look like example given

earlier ?

YES

Probe J261 &J263 Is digital data visable ?

Replace UEM

D250

Refer to Synthesiser

Fault -finding chart

Check RX/TX switch

at RX 900 Z800

Input -63 dBm

Output -63dbm

YES

Spectrum analyzer

EGSM SAW filter

Z803

output -66 dBm

YES

NO NO

Oscilloscope

check Vc1, Vc2, Vc3

at Z800 signal 0V

YES

Check

RX/TX switch

Z800

Check SAW filter

Z803

Check HELGO

N500

Spectrum analyzer

Check signal after

inductors L804 and

L805

-66 dBm YES

Oscilloscope

VR4 2.7 V

on N500

YES

Check inductors

L804, L805

Check UEM

D250

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