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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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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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

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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 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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Figure 3: RF Key Components

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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

order

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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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