LG MD120 Service Manual

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Table Of Contents

1.INTRODUCTION

1.1 Purpose ........................... .. .................................................................. .................................. 3

1.2 Regulatory Information............................................................................ ..............................3

1.3 Abbreviations .................................................... ........................... ........................... ...............6

2..Circuit Description

2.1 RF Transmit/Receive Part...... ... ..................................................... ......... ...............................8

2.2 Description of Receive Part Circuit......................................................... .............................10

2.3 Description of Transmit Part Circuit…………………………………...................……......11

2.4 Description of Frequency Synthesizer Circuit……………………...................………... ...14

2.5. Digital/Voice Processing Part………………………………………...................……..….14

2.6 Configuration………………………………………………...................……………..…...14

2.7 Briefly Circuit Description……………………………………....................………….…...15

2.8 Power Supply Part…………………………………………………...................……..……17

2.9 Logic Part…………………………………………………...................………………..….18

3. TROUBLE SHOOTING

3.1 RF Component............................................................................ .........................................21

3.2 RX Trouble.............................................................................. .............................................22

3.3 TX Trouble ........... ............. ....... ......... ......... ...... ......... ......... ....... .......... ....... ......... ................28

3.4 Power On Trouble....................................................................... .........................................35

3.5 Charging Trouble .................................................................. ...............................................37

3.6 V ibrator T rouble ....................................................... ...........................................................39

3.7 LCD Trouble........................................................................... .............................................40

3.8 Speaker Trouble .................................................................. .................................................43

3.9 Earphone Trouble ..... . .............................................................. ............................................45

3.10 KEY backlight Trouble .................................................. ...................................................47

3.11 ReceiverTrouble………………………………………………………..…....................…49

3.12 Microphone Trouble............................................................................. ..............................50

3.17 Folder on/off Trouble.................................................................... .....................................53

................................................................................................................ 3

................................................................................. ..............................8

.................................................... .............................................21

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4. APPENDIX

Total Ass

Circuit Diagram…………………………………………………………...................……..…56

PCB Layout……………………………………………………………...................……..…...60

BOM LIST………………………………………………………………..................……...….62

…………………………………………………………..................………......55

embly…………………………………………………………….....................……55

1. INTRODUCTION

1.1 Purpose

This manual provides the information necessary to repair, calibration, description

and download the features of this model.

1.2 Regulatory Information A. Security

Toll fraud, the unauthorized use of telecommunications system by an

unauthorized part (for example, persons other than your company’s employees,

agents, subcontractors, or person working on your company’s behalf) can result in

substantial additional charges for your telecommunications services. System users

are responsible for the security of own system. There are may be risks of toll fraud

associated with your telecommunications system. System users are responsible for

programming and configuring the equipment to prevent unauthorized use. The

manufacturer does not warrant that this product is immune from the above case but

will prevent unauthorized use of common-carrier telecommunication service of

facilities accessed through or connected to it. The manufacturer will not be

responsible for any charges that result from such unauthorized use.

B. Incidence of Harm

If a telephone company determines that the equipment provided to customer is

faulty and possibly causing harm or interruption in service to the telephone

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1.INTRODUCTION

network, it should disconnect telephone service until repair can be done. A

telephone company may temporarily disconnect service as long as repair is not

done.

C. Changes in Service

A local telephone company may make changes in its communications facilities or

procedure. If these changes could reasonably be expected to affect the use of the

this phone or compatibility with the network, the telephone company is required to

give advanced written notice to the user, allowing the user to take appropriate steps

to maintain telephone service.

D. Maintenance Limitations

Maintenance limitations on this model must be performed only by the

manufacturer or its authorized agent. The user may not make any changes and/or

repairs expect as specifically noted in this manual. Therefore, note that

unauthorized alternations or repair may affect the regulatory status of the system

and may void any remaining warranty.

E. Notice of Radiated Emissions

This model complies with rules regarding radiation and radio frequency emission

as defined by local regulatory agencies. In accordance with these agencies, you may

be required to provide information such as the following to the end user.

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F. Pictures

The pictures in this manual are for illustrative purposes only; your actual

1.INTRODUCTION

hardware may look slightly different.

G. Interfer ence and Attenuation

Phone may interfere with sensitive laboratory equipment, medical equipment,

etc.Interference from unsuppressed engines or electric motors may cause problems.

H. Electrostatic Sensitive Devices

ATTENTION

Boards, which contain Electrostatic Sensitive Device (ESD), are

indicated

.Service personnel should ground themselves by using a wrist strap when

exchange system boards.

. When repairs are made to a system board, they should spread the floor with

anti-static mat which is also grounded.

. Use a suitable, grounded soldering iron.

. Keep sensitive parts in these protective packages until these are used.

. When returning system boards or parts like EEPROM to the factory, use the

protective package as described.

by the sign. Following information is ESD handling:

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1.INTRODUCTION

1.3 Abbreviations

For the purposes of this manual, following abbreviations apply:

APC Automatic Power Control

AGC Automatic Gain Control

BB Baseband

BER Bit Error Ratio

CC-CV Constant Current - Constant Voltage

CDMA Code-Division Multiple Access

DAC Digital to Analog Converter

dBm dB relative to 1 milli watt

DSP Digital Signal Processing

EEPROM Electrical Erasable Programmable Read-Only Memory

ESD Electrostatic Discharge

FPCB Flexible Printed Circuit Board

GPIB General Purpose Interface Bus

IF Intermediate Frequency

LCD Liquid Crystal Display

LDO Low Drop Outpu

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LED Light Emitting Diode

PA Power Amplifier

PAM Power Amplifier Module

PCB Printed Circuit Board

PGA Programmable Gain Amplifie

PLL Phase Locked Loop

RF Radio Frequency

RLP Radio Link Protocol

RMS Root Mean Square

RTC Real Time Clock

1.INTRODUCTION

SAW Surface Acoustic Wave

SRAM Static Random Access Memory

PSRAM Pseudo SRAM

UART Universal Asynchronous Receiver/Transmitter

UIM User Identity Module

USB universal serial bus

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VCO Voltage Controlled Oscillator

VCTCXO Voltage Control Temperature Compensated Crystal Oscillator

WAP Wireless Application Protocol

ZIF Zero Intermediate Frequency

2.Circuit Description

2.1. RF Transmit/Receive Part

2.1.1 Overview

The RF transmit/receive part employs the direct conversion architecture (ZIF,

Zero IntermediateFrequency). The transmit/receive frequency is respectively

824.04~848.97 MHz and 869.04~893.97MHz. The block diagram is shown in

[Figure 2-1].

RF signals received through the antenna are fed into RFR6122 through the

duplexer. And then, they pass the low noise amplifier (LNA), combined with the

signals of local oscillator (VCO) at the frequency mixer in order to create baseband

signal directly.

Baseband signals created are changed into digital signals by the analog / digital

converter (ADC, A/DConverter) and then, auto gain controlled and, sent to the

MSM6000 (Mobile Station Modem) of the digital circuit part. Then, they are

demodulated by the modulator / demodulator.

In the case of transmission, MSM6000 modulates, interpolates, and converts the

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digital signal into an analog baseband before sending it to the RFT6122.RFT6122

receives OQPSK-modulated anlaog baseband signals from the MSM6000’s Tx part.

The RFT6122 upconverts the Tx analog baseband into RF.

The RFT6122 connects directly with MSM6000 using an analog baseband

interface. In RFT6122, the baseband quadrature signals are upconverted to the

Cellular Tx frequency bands and amplified to provide signal drive capability to the

2.Circuit Description

power amp.After that, the RF signal is amplified by the Power Amp in order to

have enough power for radiation.

Finally, the RF signal is sent out to the cell site via the antenna after going through

the duplexer.

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[Figure 2-1] RF Block Diagram Of MD120

2.Circuit Description

2.2 Description of Receive Part Circuit

2.2.1 Duplexer (DP100)

The duplexer consists of the receive part bandpass filter (BPF) and the transmit part

bandpass filter (BPF) which have the function of separating transmit/receive signals

in the full duplex system using the transmit/receive common antenna. The transmit

part BPF is used to suppress noises and spurious waves entering the receive band

among transmit signals in order to prevent the drop in receive sensitivity

characteristics. The receive part BPF blocks the signals sent out from entering the

receive end in order to improve sensitivity characteristics.

Insertion loss (IL) in the transmit band is 2.8dB (Max), whereas IL in the receive

band is 2.1dB (Max). The receive band attenuation amount of transmit filter is

51dB (Min) and the transmit band attenuation amount of receive filter is 45dB or

more (Min).

2.2.2 LNA (U103)

The RFR6122 has cellular LNA. The characteristics of Low Noise Amplifier (LNA)

are low noise figure, high gain, high intercept point and high reverse isolation. The

frequency selectivity characteristic of mobile phone is mostly determined by LNA.

The specifications of MD120 LNA are described below

Parameter Gain Mode 0(G0) Gain Mode 1(G1) Gain Mode 2(G2) Gain Mode 3(G3 Unit Gain Noise Figure Input IP3

2.2.3 Rx RF SAW FILTER (F101)

16 4 -5 -20 dB

1.5 5 5.5 20 dB

10 7 15 15 dBm

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The main function of Rx RF SAW filter is to attenuate mobile phone spurious

2.Circuit Description

frequency, attenuate noise amplified by the LNA and suppress second harmonic

originating in the LNA.

2.2.4 Down-Converter Mixers (U103)

The RFR6122 device performs signal direct-down-conversion for Cellular

applications. It contains all the circuitry (with the exception of external filters)

needed to support conversion of received RF signals to baseband signals. The LO

Buffer Amplifier buffers the RF VCO to the RF Transmit Upconverter. RFR6122

offers the most advanced and integrated CDMA Rx solution designed to meet

cascaded Noise Figure (NF) and Third-order Intercept Point (IIP3) requirements of

IS-98C and J-STD-018 specifications for Sensitivity, Two-Tone Intermodulation,

and Single-tone Desense. Operation modes and band selection are specially

controlled from the Mobile Station Modem MSM6000.

The specification of MD120 Mixers are described below:

Parameter High Gain Mode Low Gain Mode Unit

Noise Figure Input IP3 Input IP2

10 25 dB 4 0 dBm 56 30 dBm

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2.3 Description of Transmit Part Circuit

2.3.1 Description on the Internal Circuit of MSM6000 (U201) and RFT6122 (U102)

For the transmit data path(Tx), the MSM6000 modulates, interpolates, and converts

the digital signal into an analog baseband before sending it to the RFT6122. The

RFT6122 upconverts the Tx analog baseband into RF. The MSM6000

communicates with the external RF and analog baseband to control signal gain in

the RF Rx and Tx signal paths, educe base band offset errors, and tune the system

2.Circuit Description

frequency reference. The RFT6122 baseband-to-RF Transmit Processor performs

all Tx signal-processing functions required between digital baseband and the Power

Amplifier Module (PAM). The baseband quadrature signals are upconverted to the

Cellular frequency bands and amplified to provide signal drive capability to the

PAM. The RFT6122 includes an mixer for up-converting analog baseband to RF, a

programmable PLL for generating Tx and Rx LO frequency, cellular driver

amplifier and Tx power control through an 85 dB VGA. As added benefit, the

single sideband upconversion eliminates the need for a band-pass filter normally

required between the upconverter and driver amplifier. I, I/, Q and Q/ signals

proceed from the MSM6000 to RFT6122 are analog signal. In CDMA mode,

These signals are modulated by Offset Quadrature Phase Shift King (OQPSK). I

and Q are 90 deg. out of phase, and I and I/ are 180 deg. The mixer in RFT6122

converts baseband signals into RF signals. After passing through the upconverters,

RF signal is inputted into the Power Amplifier Module.

The RFT6122 Cellular CDMA RF specifications are described below:

Rated Output Power Min Output Power Rx band noise power ACPR

2.3.2 Power Amplifier (U104)

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Condition Min. Typ. Max. Unit

Average CDMA Cellular 6 dBm Average CDMA Cellular -75 dBm CDMA Cellular -132 dBm/Hz Cellular: Fc±885kHz Fc±1.98MHz

-52

-63

dBc

The power amplifier that can be used in the CDMA mode has linear amplification

capability. For higher efficiency, it is made up of one module (Monolithic

2.Circuit Description

Microwave Integrated Circuit) for which RF input terminal and internal interface

circuit are integrated onto one IC after going through the GaAs HBT(heterojunction

bipolar transistor) process.

The module of power amplifier is made up of an output end interface circuit

including this module. The maximum power that can be inputted through the input

terminal is +7dBm and conversion gain is about 28.5dB. RF transmit signals that

have been amplified through the power amplifier are sent to the duplexer.

2.4 Description of Frequency Synthesizer Circuit

2.4.1 Voltage Controlled Temperature Compensation Crystal Oscillator (X100)

The temperature range that can be compensated by VC-TCXO which is the

reference frequency generator of a mobile station is -30~+80 °C.

VC-TCXO receives frequency tuning signals called TRK_LO_ADJ from

MSM6000 as 0.5V~2.5V DC via R and C filters in order to generate the reference

frequency of 19.20MHz and input it into the frequency synthesizer of UHF band.

Frequency stability depending on temperature is ±2.0 ppm.

2.4.2 Voltage Controlled Oscillator (U103)

The internal VCO signal of RFR6122 is processed by the LO generation and

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distribution circuits in RFR6122 to create Cellular quadrature downconverter’s LO

signals. The LO signals applied at the mixer ports are at the frequency different

than the VCO frequency. This assures that the VCO frequency is different than the

RF frequency, an important consideration for Zero-IF processing. The VCO

frequency used are 1738.08~1787.94MHz for cellular and It is produced in single

2.Circuit Description

voltage controlled oscillator of U106.

2.5. Digital/Voice Processing Part

2.5.1 Overview

The digital/voice processing part processes the user's commands and processes all

the digital and voice signal processing in order to operate in the phone. The

digital/voice processing part is made up of a keypad/LCD, receptacle part, voice

processing part, mobile station modem part, memory part, and power supply part.

2.6 Configuration

2.6.1 Keypad/LCD and Receptacle Part

This is used to transmit keypad signals to MSM6000. It is made up of a keypad

backlight part that illuminates the keypad, LCD part that displays the operation

status on to the screen, and a receptacle that receives and sends out voice and data

with external sources.

2.6.2 Voice Processing Part

The voice processing part is made up of an audio codec in MSM6000 used to

convert MIC signals into digital voice signals and digital voice signals into analog

voice signals, amplifying parts for amplifying the voice signals and MIC signals are

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on Codec in MSM6000.

2.6.3 MSM6000 (Mobile Station Modem) Part

MSM6000 is the core elements of a CDMA mobile station and carries out the

functions of CPU, encoder, interleaver, deinterleaver, Viterbi decoder, Mod/Demod,

codec, and vocoder.

2.6.4 Memory Part

The memory part is made up of a flash memory and a SRAM

2.Circuit Description

2.6.5 Power Supply Part

The PMIC(PM6610-2) is made up of 7 Regulators and direct connet to Batt.

Regulator(150mA)s give the power each Circuits(RFT6122/RFR6122).

Regulator(150mA) gives the power to the MSM and memory parts. PAM, Motor,

LCD back light LED, Indicator LED, Keypad LED and Audio amplifier are directly

conneted to Battery.

2.7 Briefly Circuit Description

2.7.1 Keypad/LCD and Receptacle Part

Once the keypad is pressed, the key signals are sent out to MSM6000 for

processing. In addition, when the key is pressed, the keypad lights up through the

use of 10 LEDs. The status and operation of a mobile station are displayed on the

screen for the user with the characters and icons on the LCD

Receptacle(CON400) exchanges audio signals and data with external sources and

then, receives power from the battery or external batteries.

2.7.2 MSM Part

MSM6000 is the core element of a CDMA mobile station. Subsystems within the

MSM6000 include a CDMA processor, an EVRC(Enhanced Variable Rate Codec)

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vocoder, an ARM7TDMI microprocessor ,and assorted peripheral interfaces that

are used to support other functions. MSM6000, when operated in the CDMA mode,

utilizes CHIP×8 (9.8304MHz) as the reference clock primarily for CDMA and

vocoder processing.MSM6000 also uses TCXO/4 (4.92MHz). The CPU controls

total operations of the subscriber unit. Digital voice data, that have been inputted,

are encoded using the EVRC algorithm. Then, they are convolutionally encoded so

2.Circuit Description

that error detection and correction are possible. Coded symbols are interleaved in

order to avoid a burst error. Each data channel is scrambled by the long code PN

sequence of the user in order to ensure the confidentiality of calls.

Moreover, binary quadrature codes are used based on Walsh functions in order to

discern each channel. Data created thus are 4-phase modulated by one pair of Pilot

PN code and they are used to create I and Q data.

When received, I and Q data are demodulated into symbols by the demodulator and

then, de-interleaved in reverse to the case of transmission. Then, the errors of data

received from Viterbi decoder are detected and corrected. They are voice decoded

at the vocoder in order to output digital voice data.

The MSM6000 also supports Enhanced Variable Rate Coder (EVRC) operation in

addition to the standard 8k.

2.7.3 Audio Processing Part

MIC signals are inputted into the audio codec, and amplified with programmable

gain, and converted into digital signals(PCM). Then, they are inputted into

MSM6000. In addition, digital audio signals(PCM) outputted from MSM6000 are

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converted into analog signals after going through the audio codec. These signals are

amplified with programmable gain on codec’s internal AMP and external Audio

AMP and then transferred to the ear piece. The signals is generated in MSM6000

using SW MIDI.

2.7.4 Memory Part

The memory part consists of a 32Mbits Flash Memory and a 16Mbits SRAM. In the

2.Circuit Description

Flash Memory, there are programs used for the operation of a mobile station. The

programs can be changed through down loading after the assembling of mobile

stations. The Flash memory is also emulated as an EEPROM to store

ESN(Electronic Serial Number), Calibration Data, etc. On the SRAM, data

generated during the operation of a mobile station are stored temporarily.

2.8 Power Supply Part Turn ON

When the battery voltage (4.2V ~ 3.3V) is fed and the PWR key of keypad is

pressed, PMIC is activated by the ON_SW signal, and then the control signal

ON_SW_S/ signal is generated. And then, the regurator 2.4V_MSMC &

2.8V_MSMP, 2.6V_MSMA, are operated.

Operating

During the phone is on operating state, LDO(in PMIC) for MSM is always enable

and gives the power MSM6000 and memory part LDO(in PMIC) for +2.6V_TX

part is enabled on IDLE/ state, and gives the power TX part devices. LDO(in PMIC)

for +2.6V_RX part is enabled on SLEEP/ state, and gives the power RX part

devices

Turn OFF

When the PWR key is pressed during a few seconds, PMIC is turned on by ON_SW

and then, 'Low' is outputted on ON_SW_S/. MSM6000 receives this signal and then,

recognizes that the POWER key has been pressed. During this time, MSM6000

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2.Circuit Description

outputs PS_HOLD as low and turn off all devices

[Figure 1-2] Block Diagram Of Power Management IC

2.9 Logic Part

The Logic part consists of internal CPU of MSM6000, MEMORY. The MSM6000

receives TCXO/4 clock(19.20Mz) and CHIPX8 clock signals, and then controls the

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phone during the CDMA and the FM mode. The major components are as follows:

CPU : ARM7TDMI microprocessor core

MEMORY : S71PL064JB06AWOUO

CPU

ARM7TDMI 32-bit microprocessor is used and CPU controls all the circuitry.

Some of the features of the ARM microprocessor include a 3 stage pipelined RISC

2.Circuit Description

architecture, both 32-bit ARM and 16bit THUMB instruction setsm, a 32-bit

address bus, and a 32-bit internal data bus.

MEMORY ARCHITECTURAL ADVANTAGES

■64 Mbit Page Mode devices

—Page size of 8 words: Fast page read access from random locations within the page

■Single power supply operation

—Full Voltage range: 2.7 to 3.6 volt read, erase, and program operations for battery-powered applications

■Simultaneous Read/Write Operation

—Data can be continuously read from one bank while executing erase/program functions in another bank

—Zero latency switching from write to read operations

FlexBank Architecture (PL064J)

—4 separate banks, with up to two simultaneous operations per device

—Bank A: PL064J - 8 Mbit (4 Kw x 8 and 32 Kw x 15)

—Bank B: PL064J - 24 Mbit (32 Kw x 48)

—Bank C: PL064J - 24 Mbit (32 Kw x 48)

—Bank D: PL064J - 8 Mbit (4 Kw x 8 and 32 Kw x 15)

Enhanced VersatileI/OTM (VIO) Control

—Output voltage generated and input voltages tolerated on all control inputs and I/Os is determined by

the voltage on the VIO pin

—VIO options at 1.8 V and 3 V I/O for PL127J devices

—3V VIO for PL064J and PL032J devices

SecSiTM (Secured Silicon) Sector region

—Up to 128 words accessible through a command sequence

—Up to 64 factory-locked words

—Up to 64 customer-lockable words

Both top and bottom boot blocks in one device

■Manufactured on 110 nm process technology

■Data Retention: 20 years typical

■Cycling Endurance: 1 million cycles per sector typical

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PERFORMANCE CHARACTERISTICS

■High Performance

—Page access times as fast as 20 ns

—Random access times as fast as 55 ns

2.Circuit Description

■Power consumption (typical values at 10 MHz)

—45 mA active read current

—17 mA program/erase current

—0.2 µA typical standby mode current

KEYPAD

For key recognition, key matrix is setup using KEY_SENSE0-4_N signals and

GPIO32~36 of output ports of MSM6000. Backlight circuitry are included in the

keypad for easy operation in the dark.

LCD MODULE

LCD module contains a controller which will display the information onto the LCD

by 8-bit data from the MSM.

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U100

U101

U102

F100

3.1 RF Component

Figure 1

U100 Mobile Switch

U100 Mobile Switch U101 LOAD-SWITCH

U101 LOAD-SWITCH U102 RF-TRANSMITTER

U102 RF-TRANSMITTER

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U103 RF-RECEIVER

U103 RF-RECEIVER U104 PAM

U104 PAM F100 SAW-FILTER

F100 SAW-FILTER F101 SAW-FILTER

F101 SAW-FILTER X100 VCTCXO

X100 VCTCXO DP100 DCN-DUPLEXER

DP100 DCN-DUPLEXER

3.TROUBLE SHOOTING

U104

X100

DP100

F101

U103

3.TROUBLE SHOOTING

3.2 RX Trouble

CHECKING FLOW

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START

Set RX test（HHP）

。test mode -d

。CH“400”

Set E5515C

。CH：400

。CELL POWER：-30dBm

Spectrum Analyzer Setting

Oscilloscope Setting

(1) Check

PMIC circuit

(2) Check VCTCXO

(3) Check

Mobile SW

&FEM

(4) Check

RX IQ

Redownload SW or

Do calibration again

(1) Checking PMIC Circuit

CIRTUIT DIAGRAM

Check pin 31 o

f U300

TEST POINT

U300,PIN31 (+2.6V_RX)

Checking Flow

3.TROUBLE SHOOTING

U300,PIN7

(PS_HOLD)

Check pin 7

of U300

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+2.6V_RX

OK?

Yes

PMIC is ok,,see t

he next page

to check the

VCTCXO

PS_HOLD

is high?

Yes

Replace U300

Changing the

board

+ 51 hidden pages

LG MD120 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual