Prestigio PSP3502 User manual

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SERVICE MANUAL
For Cellular Phone
Model Name: PSP3502

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Version: A
Effective Date: 2014.04.27

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Note:
This manual is guide to after-sales repair of DA34681 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

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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. Assembl y and Disassembly
6.1 product appearance
6.2 Introductions of disassembly
7. Rep air 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 and GPS 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

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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:
DA34681 mobile phone are based upon platform MT6582, including baseband
circuit and frequency circuits, Baseband parts is mainly comprised of master
chip MT6582 and its controlled peripheral circuits. DA34681 is equipped with
dual SIM and dual standby, double camera, single battery, CTP，G-sensor，
WIFI，FM, Bluetooth and single memory card.
Main Features:
Main dimension: 146*73*10.1 mm
Smart phone
Optional band (GSM 900 \ 1800 \ 850 \ 1900\W2100)
Display: 5.0’HD
Camera: 8M\5M image elements
Voice recording

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Antenna: GSM antenna, FM earphone antenna, BT/WiFi/GPS 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)
Class 1(1W)/(DCS/PCS)
Class 3(200mW)(W2100/W850)
Voltage range: 3.7 ~ 4.2V
Battery capacity: 1850mAh
Item GSM Technical Indexes DCS Technical Indexes
Frequency Range Transmit : 880~915MHz
Receiver : 925~960MHz
Transmit: 1710~1785MHz
Receiver: 1805~1880MHz
Channel 174 Carrier wave, 8 channels
per carrier wave
174 Carrier wave, 8 channels per
carrier wave
Phase Error RMS Less than 5 degrees, Peak
value less than 20 degrees
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 ℃
Item GSM850 Technical Indexes PCS Technical Indexes
Frequency Range Transmit : 824~849MHz
Receiver : 869~894MHz
Transmit: 1850~1910MHz
Receiver: 1930~1990MHz
Channel 174 Carrier wave, 8 channels
per carrier wave
174 Carrier wave, 8 channels per
carrier wave
Phase Error RMS Less than 5 degrees, Peak
value less than 20 degrees
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 ℃

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Output powers of transmitters of different power levels (GSM900)
Power Control
level
Output Power
of transmitter Error
dBm Normal(dB) Limit(dB)
5 33 ±3 ±4
6 31 ±3 ±4
7 29 ±3 ±4
8 27 ±3 ±4
9 25 ±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
17 9 ±5 ±6
18 7 ±5 ±6
19 5 ±5 ±6
Output powers of transmitters of different power levels (GSM850)
Power Control
level
Output Power
of transmitter Error
dBm Normal(dB) Limit(dB)
5 33 ±3 ±4
6 31 ±3 ±4
7 29 ±3 ±4
8 27 ±3 ±4
9 25 ±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
17 9 ±5 ±6
18 7 ±5 ±6
19 5 ±5 ±6

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Output powers of transmitters of different power levels (DCS1800)
Power Control
level
Output Power
of transmitter Error
dBm Normal(dB) Limit(dB)
0 30 ±3 ±4
1 28 ±3 ±4
2 26 ±3 ±4
3 24 ±3 ±4
4 22 ±3 ±4
5 20 ±3 ±4
6 18 ±3 ±4
7 16 ±3 ±4
8 14 ±3 ±4
9 12 ±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
Output powers of transmitters of different power levels (PCS1900)
Power Control
level
Output Power
of transmitter Error
dBm Normal(dB) Limit(dB)
0 30 ±3 ±4
1 28 ±3 ±4
2 26 ±3 ±4
3 24 ±3 ±4
4 22 ±3 ±4
5 20 ±3 ±4
6 18 ±3 ±4
7 16 ±3 ±4
8 14 ±3 ±4
9 12 ±4 ±5
10 10 ±4 ±5
11 8 ±4 ±5
12 6 ±4 ±5
13 4 ±4 ±5
14 2 ±5 ±6

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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.

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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

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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:

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RF part :
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 U1102 (Output frequency
26MHz and ±10ppm accuracy) and related RC components.
RF main chip: RF master chip internally integrates RF IC (U1101), Mixer,
U1101 RF
Transceiver
U1102 26MHz
Cr
y
stal
RX SA W : U1 103 ;
DPX:U1104/U1105/U11
06/U1207
U1201 Ante nna Switch + GSM
PA; U1203/U 1204/U1206
/U1206 WCDMA PA
U1202 RF
Connector
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VBAT
26MHz

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LNA, PGA, Amplifier, GMSK modem (GMSK modem exclude from RF chip),
PLL etc.
RF Amplifier circuit U1201: The periphery of U1101 mainly includes
resistance, capacitor and inductance components. U1201 is directly powered
by batteries.
BB Parts:
Include analog baseband chip, Flash, audio, keys, SIM Card slot, battery
connector, micro USB connector (5pin), charger circuit etc.
6. Assembly and Disassembly:
Product appearance:
Front view

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Back view
Instruction of disassembly:
Tool for repair: Tweezers, case removing tool, standard cross head
screwdriver

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Disassem bly Steps:
Removing the battery : Push the battery cover in the direction of the red arrow,
and take the battery cover off, and take the battery off.

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Removing the upper house:
Unscrew the 10 screws fixed on lower housing, the position of screws shown
as red circles of the following picture, and according to the order of
A--->B--->C--->D--->E--->F--->G--->H--->I--->J:
Poke on the ZIF cover on motherboard, remove the FPC, Unscrew
7. Repair requirement:
Precautions:
A reliable work area must be available so that ESD-sensitive components are
safely used and no electrostatic shock occurs. This work area must be
configured as follows:
Work surfaces ----- All work surfaces must be covered with anti-static mats.
For the protection of powered equipment these mats must be grounded
through a connection with 1.2ohm resistance
Bracelet ----- A fixture with a soft wire and built-in resistance of 5.2ohm to
1.2ohm for quick dissipation of static electricity. The soft wire connection is
attached to common-ground.
Posy-rep air Testing:
After repairs, tests must be carried out on the product to assure that its
operation is normal. When the component on main board is replaced, mobile
phone must be tested out on the fixture to assure that its operation is normal.
Testing is even more important in the case of replacement of logic or RF
compatible communications analyzer.
Attention: You must have the necessary equipment as well as the necessary
service training in order to repair CPU flash…
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8. Baseband Trouble
8.1 Flash programming does not download
Analysis Process：
8.2 Phone does not “power on”
Power on principle of phone:
When the power supply is connected with the phone, through internal
switching circuit in the boot it will form a trigger High-level, when press boot
button long enough, the boot high-level change to low-level because of
connecting with GND, and the signal reaches PMU block, PMU will activate
the internal voltage regulator and output stable voltage, as a logical part of the
core CPU will gain power supply.
We know phone boot in three necessary conditions: Power Supply, clock
and reset. Now power supply has been provided, then Crystal will produce 26

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MHz clock signal, on the one hand it will be taken as a RF reference clock, on
the other hand, it will be sent to logic to the clock signal. After the clock signal
reaches the microprocessor, the memory before need be cleared, therefore
PMU will send reset signal to it for initialization. After the initialization is
finished, it outputs control commands to memory, then memory will change to
permit state, and then through address line to look up where boot program is,
after finding the boot program it will be sent to CPU internal DSP circuit
through data lines. After the successful operation, the CPU output signal to
PMU, the power supply will continuously output voltage to complete booting.
After phone powers on, the CPU calls RF parameters from flash, through
radio BCCH to receive the signal intensity in the area, if your phone has a SIM
card or UIM cards, Mobile phone will send the information in SIM card to the
BS, and receives information from the BS, thus achieve network connections.
After being connected with networks, mobile phones will be in an idle
mode, but also mobile phones through SACCH periodically exchange some
information with base stations, such as signal strength and frequency
synchronization, receiving level, and receiving quality.
Analysis Process：

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8.3 Sound trouble
Analysis Process：
Reference circuit as follows：
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8.4 Can not charge up
Charging principle introduction:
The battery charger is optimized for the Li-ion batteries. The typical

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charging procedure can be divided into three phases: pre-charging, constant
current mode charging, and constant voltage mode charging. Follow figure
shows the flow chart of the charging procedure. Most of the charger circuits
are integrated in the PMU except for one PNP transistor, one NMOS and one
accurate resistor for current sensing. Those components should be applied
externally.
Analysis Process：