Explay Atom, Atom schematic SM Atom Service Manual

SERVICE MANUAL

For Cellular Phone

Model Name: Atom

Version: A

Effective Date: 2013.08.20

Note:

This manual is guide to after-sales repair of Atom mobile phone, the repair of

product shall only be carried out by trained and well experienced technical

person and use of this manual by any other person for the service of the

product may result in serious damage to the product

Content

1. Introduction

1.1 Purpose

1.2 General safety Guidelines and use

2. General Characters

2.1 Overview

2.2 Introduction to main Functions

3. Introduction to capability and index

4. How the GSM system work

4.1 General

4.2 Introduction of GSM

5. System overview

5.1 RF Part

5.2 BB part

6. Assembly and Disassembly

6.1 product appearance

6.2 Introductions of disassembly

7. Repair requirement

8. Baseband Trouble

8.1 Flash programming does not download

8.2 Phone does not “power on”

8.3 Sound trouble

8.4 Can not charge up

8.5 LCD trouble

8.6 Microphone trouble

8.7 Earphone part trouble

8.8 Vibrator trouble

8.9 Receiver does not work

8.10 Camera trouble

8.11 WIFI and FM and BT circuit trouble

8.12 G-sensor has not function

8.13 Phone can not access SIM card

8.14 TF card trouble and TF card Circuit Working Principle

9. RF Trouble

9.1 Principle of operation

9.2 AGC failure

9.3 AFC failure

9.4 APC Failure

10.Maintenance tools

1. Introduction:

1.1 Purpose:
The main purpose of this manual is to provide a basic foundation for electrical
and mechanical repairs

1.2 General Safety guidelines and use:

Safety guidelines:
The product contains polar capacitors, which must not be short-circuited or
connected with polarities reversed. During repairs, due attention shall be paid
to static protection in order not to damage the ESD-sensitive components of
this device. It is strictly forbidden to use mobile phone dial up in the plane. It is
strictly forbidden to use this device near aerosol sprays or explosive gases

Use of mobile phone:
Please do not make mobile phone approach or touch the exposed parts of the
body(especially face or eye), If the user holds the mobile phone like the
receiver of a common telephone, it has best efficiency when its antenna is
upwards and above the shoulder. Please speak to microphone.
Each driver shall always pay attention to safety, Use of a mobile phone when
she/he drives in some areas is an illegal act.

2. General characters:

2.1 Overview:
DX33681 mobile phone are based upon platform MT6572W, including
baseband circuit and frequency circuits, Baseband parts is mainly comprised
of master chip MT6572W and its controlled peripheral circuits. DX33681 is
equipped with dual SIM and dual standby, dual camera, single battery, CTP
G-sensor，WIFI，FM, Bluetooth ,GPSand single memory card.

Main Features:

Main dimension: 144.8*71*8.9mm
Smart phone
Optional quad band(GSM850/GSM900/DCS1800/PCS1900)+triple

WCDMA(band1/band5/band8)

，

Display: 4.0” WVGA LCD
Camera: 5.0M image elements back camera and 2.0M image elements

front camera

Voice recording
Antenna: GSM antenna, FM earphone antenna
Charger: Micro USB charger
SIM: dual band and dual standby
Support MSN, Yahoo, Message, face book, ect

3. Introduction to capability and index:
Operating temperature: -10℃~+55
Storage temperature: -10℃~+60

℃

℃

Relative humidity: 10% ~ 95%
Transmit power: Class 4(2W)/(EGSM/GSM850)

Clasee1(1W)/(DCS/PCS)
Voltage range: 3.5 ~ 4.2V
Battery capacity: 2000mAh

Item GSM Technical Indexes DCS Technical Indexes

Frequency Range

Channel

Phase Error

Bit Error Rate <2% <2%

Receiving Sensitivity <-102dBm <-102dBm

Voltage Range 3.2~4.5V

Temperature Range —10℃~+55

Item GSM850 Technical Indexes PCS Technical Indexes

Frequency Range

Channel

Phase Error

Transmit : 880~915MHz
Receiver : 925~960MHz

174 Carrier wave, 8 channels

per carrier wave

RMS Less than 5 degrees, Peak

value less than 20 degrees

Transmit : 824~849MHz
Receiver : 869~894MHz

174 Carrier wave, 8 channels

per carrier wave

RMS Less than 5 degrees, Peak

value less than 20 degrees

Transmit: 1710~1785MHz
Receiver: 1805~1880MHz

174 Carrier wave, 8 channels per

carrier wave

RMS Less than 5 degrees, Peak

value less than 20 degrees

℃

Transmit: 1850~1910MHz
Receiver: 1930~1990MHz

174 Carrier wave, 8 channels per

carrier wave

RMS Less than 5 degrees, Peak

value less than 20 degrees

Bit Error Rate <2% <2%

Receiving Sensitivity <-102dBm <-102dBm

Voltage Range 3.2~4.5V

Temperature Range —10℃ ~+55℃

Output powers of transmitters of different power levels (GSM900/GSM850)

Power

Control

level

533±3±4
631±3±4
729±3±4
827±3±4

925±3±4
10 23 ±3 ±4
11 21 ±3 ±4
12 19 ±3 ±4
13 17 ±3 ±4
14 15 ±3 ±4
15 13 ±3 ±4
16 11 ±5 ±6

Output Power

of transmitter

dBm Normal(dB) Limit(dB)

Error

17 9 ±5 ±6
18 7 ±5 ±6
19 5 ±5 ±6

Output powers of transmitters of different power levels (DCS1800/PCS1900)

Power

Control

level

030±3±4

128±3±4

226±3±4

324±3±4

422±3±4

520±3±4

618±3±4

716±3±4

Output Power

of transmitter

dBm Normal(dB) Limit(dB)

Error

814±3±4

912±4±5
10 10 ±4 ±5
11 8 ±4 ±5
12 6 ±4 ±5

13 4 ±4 ±5
14 2 ±5 ±6
15 0 ±5 ±6

4. How the GSM system work:

4.1 General:
The following is a basic introduction to the GSM (Global system for mobile
communication) cellular network. This introduction has been greatly simplified
and cannot describe all the working performances and technologies or
technologies used by the system.

4.2 Introduction of GSM:

Unlike analog cellular systems, GSM use digital wireless technology,
compared with previous analog systems, GSM system has the benefits,:

International roaming: Thanks to international consistency and
standardization, calls can be sent and received in any country supporting
GSM.

Digital air interface: The connection between GSM phones and base station
is fully digital, and furthermore, GSM digitally connects to switching
subsystems and accesses the public switched telephone network.

Security: Calls made over analog system can be listened in with ease using
the appropriate radio receiver. GSM greatly improves security as data is sent
after being digitally encrypted.

Better voice quality: Digital systems are more effective at dealing with same
channel interference, transmission interruption and attenuation. Voice quality
can also be improved through error correction (by rebuilding lost information)

Efficiency: The GSM system can make more efficient use of spectrum
resources than analog system of the past.

In the following diagram, the think line represents the total coverage area of a
hypothetical system. This area is further divided into a number of cells, each of
which includes a cell station (base station), each base station works on a set of
given channels, and connects wireless phone subscribers and the telephone
switching system.

For example, assuming that cell A works in channels 1~8(Numbering is
arbitrary), cell B works in channels 9~16 and cell C works in channels 17~24,
cell D can works in channels 1~8(reusing the channels used by cell A). In this
system, subscribers in cells A and D can use channels 1~8 at the same time.

This means that cells using the same frequencies can be physically closer in a
GSM system than in an analog system, consequently, the advantages of
reusing frequencies become all the more obvious with a GSM system. In
dense subscriber areas, a GSM system can achieve an enhanced traffic
handing rate.

A wireless telephone itself can work on any channel of a system and in this
way, it can work in any cell, because only very low power is necessary for the
communications between a wireless phone and a base station within a specific
cell.

Frequency reuse technology improves the system’s call handling ability
without requiring an increase in the number of channels. However, when the
same frequency is used within a small scope, same-channel interference may
occur. By using digital modulation, forward error correction and load balancing
technology, a GSM system can tolerate more same-channel interference than
analog system.
Through the use of Time Division Multiple Access(TDMA) technology, multiple
calls can share the same carrier. The carrier is divided into continuous TDMA
frame streams. Each frame is divided into 8 time slots. As a connection is

made, the system allocates a dedicated time slot from each TDMA frame, and,
after digitalization, the subscriber data(voice/data) is broken up into blocks.
The subscriber data blocks are sent in the allocated slots of each TDMA frame
in the form of an information pulse.

Utilize Gaussian Minimum Shift keying(GMSK) --- a highly efficient method of
phase modulation, to modulate the data blocks into the carrier.

An information pulse is sent each time and different information pulses may be
sent at different frequencies. This process is referred to as frequency hopping,
Frequency hopping reduces the effect of attenuation and increased the
security of a link. A GSM wireless phone does not need to continuously
transmit but rather only send a pulse in each frame, making the mobile phone
even more power efficient.
Each wireless phone shall be allowed to be moved from one cell to another cell
without causing inconvenience to the subscriber. The mobile phone itself can
measure the signal neighboring cells and quality of a voice channel is
measured together by the mobile phone and base station. Through precise
transfer criteria, transfer should be completed before the subscriber perceives
that the quality of the channel deteriorates.

When a wireless phone is located in the middle of a cell, signal intensity will be
very high. The intensity and quality of the signal will decrease with the
movement of the wireless phone toward the edge of the cell.

Signal information indicates the distance of a subscriber from the base station.
When a wireless phone moves between cells, control is also transferred
among the base station. This type of transfer is carried out by the wireless
phone and the base station and is fully transparent to the subscriber.

5. System overview:

RF part :

y

RX SAW : U103 ; DPX:
U104/U105/U106

U202 RF
Connector

U201 Antenna Switch + GSM
PA ; U203/U204/U205 WCDMA
PA

U101 RF
Transceiver

VBAT

26MHz

U102 26MHz
Cr

stal

RF (Radio Frequency) section is composed of 26MHz crystal, RF main chip,
Saw filter, RF connector,Antenna Switch, RF Amplifier

26MHz Crystal circuit: Mainly comprised of U101 (Output frequency 26MHz

and ±10ppm accuracy) and related RC components.

RF main chip: RF master chip internally integrates RF IC (U101), Mixer,
LNA, PGA, Amplifier, GMSK modem (GMSK modem exclude from RF chip),
PLL etc.

RF Amplifier circuit U201: The periphery of U101 mainly includes resistance,
capacitor and inductance components. U201 is directly powered by batteries.

BB Parts:
Include analog baseband chip, Flash, Crystal oscillator (32.768KHz), BT chip,
FM chip, WIFI chip MIC, keys, SIM Card slot, battery connector, micro USB
connector (5pin), charger circuit etc.

6. Assembly and Disassembly:
Product appearance:

Front view