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SERVICE MANUAL
----DS115
Date Version Maintenance Level Author
December 15, 2012
V1.0 L1~L4 Cheney Chen
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TABLE OF CONTENTS
CAUTIONS……………………………………………….…………………………..….……….4
GENERAL REPAIR INFORMATION……………………..……………………..……….…….5
Chapter 1
SERVICE TOOLS
…………………………………………………………………….………….…….....7
Chapter 2 Baseband Circuit Analysis
Mobile solution diagram ….……..……………………………………….……………………9
Baseband Block Diagram
Baseband Chip Pin Description
.……..…………………………………………………………9
……………………………………………….………………12
2.2.1 MCU subsystem ……………….....…………………..................……….………………12
2.2.2 extra memory description ……………………........………………………..……….………15
2.2.3 camera subsystem ……………….................…........………………………..……….………18
2.2.4 Audio process subsystem………………...................………………………..……….………19
2.2.5 Power Manager subsystem….......……...................………………………..……….………23
2.2.6 I/O interface circuit……………….......................................……………………….…….…..32
Chapter 3 RF Circuit Analysis
Mobile solution diagram…………………………………………………………………………33
RF receiver circuit description …………………………………………………………………….35
RF transit circuit description
……………………………………………………..……………….36
Chapter 4 Trouble shooting
Turning on failure ------L1~L2
………………………………………………..………………..37
Turning on failure ------no current………………………………………………………………….38
Turning on failure ------10~30mA………………………………………………………………….39
Turning on failure ------large current……………………………………………………..……….40
Ringtone failure------L1~L2 ……………. ……………….………………………………………..41
Ringtone failure------L3~L4 ……………. …….…………………………………………………..42
No display------L1~L2 …………….……………………………………………………………....43
No display------L3~L4……………….……………………………………………………………....44
Download circuit failure------L1~L2……………….……………………………………………...45
Download circuit failure------L3~L4……………….……………………………………………...46
Keypat circuit failure-……………….……....................……...........................…………………...47
T-flash reader circuit failure------L3~L4…………………………………………………………...48
Dual SIM failure------L1~L2.……..……………………………………………………..…………..49
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Camera circuit failure-……………….……………...........................…………………...50
Call in failure------L1~L2.……..……………………………………………………........51
Call in failure------L3~L4……..………………………………………………………..…………..52
Call out failure------L1~L2.……..…………………………………………………………………..53
Call out failure------L3~L4……..…………………………………………………………………..54
Chapter 6 Appendix……………..…………………………………………………....................55
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CAUTIONS
Please refer to the phone’s user’s guide for instructions relating to operation, care,
and maintenance, which include important safety information.
1. Servicing and alignment must be undertaken by qualified personnel only.
2. Ensure all work is carried out at an anti-static workstation and that an anti-static
wrist strap is worn.
3. Use only approved components as specified in the parts list.
4. Ensure all components, modules, screws, and insulators are correctly re-fitted
after servicing and alignment
5. Ensure all cables and wires are repositioned correctly
Electrostatic discharge can easily damage the sensitive components of electronic
products. Therefore, every service supplier must observe the precautions which
mentioned above.
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GENERAL REPAIR INFORMATION
1. Make sure your testing equipment is functioning properly before beginning repair
work.
2. Before starting repairs you must observe ESD precautions such as being in your
ESD protected area and connecting your wristband.
3. Use gloves to avoid corrosion and fingerprints.
4. Cover windows and displays with a protective film to avoid dust and scratches.
5. Use a lint-free cloth to clean the LCD.
6. When cleaning the pads use a soft cloth\ESD brush and isopropanol .
7. Non-faulty mechanical parts (except shielding lids and bent parts or soldered
components). May be reused if they are not soldered.
8. When removing the shielding lids make sure to cover it back or replace them with
new ones, otherwise the high-frequency leakage can affect the device.
9. Always use the original spare parts.
10. Check the soldering joints of the parts concerned with regard to the fault
symptom. And re-solder them if necessary.
11. Remove excess soldering flux after repair.
12. Observe the torque requirements when assembling the unit.
13. please aware that some malfunctions may be software related and solved by an
update
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Chapter 1
Service tools
850 Rework station & Solder Iron
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DC Power supply
Multimeter
Digital Oscillograph
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Screw driver and tweezer
Solder wire
Flux paste
Wrist grounding strap, Antistatic gloves
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Serial flash chipset
BB chipset
26MHz crystal
Filter
PA
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Chapter 2
Baseband Circuit Analysis
2.1 Mobile solution diagram
MT6250 is a monolithic chip integrating leading edge power management unit, analog
baseband and radio circuitry based on the low-power CMOS process.
MT6250 is a feature-rich and extremely powerful single-chip solution for high-end SM/GPRS
and EDGE-Rx capability. Based on the 32-bit ARM7EJ-STM RISC processor, MT6250’s
superb processing power, along with high bandwidth architecture and dedicated hardware
support, provides a platform for high-performance GPRS/EDGE-Rx Class 12 MODEM
application and leading-edge multimedia applications.
Figure 2-1: Solution Diagram
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MT6250 is capable of running the ARM7EJ-STM RISC processor at up to 260MHz,
which provides the best trade-off between system performance and power consumption.
For large amounts of data transfer, high-performance DMA (Direct Memory Access) with
hardware flow control is implemented, which greatly enhances the data movement speed while
reducing the MCU processing load.
Targeted as a media-rich platform for mobile applications, MT6250 also provides
hardware security digital rights management for copyright protection. For further safeguard
and to protect the manufacturer’s development investment, hardware flash content protection
is provided to prevent unauthorized porting of the software load.
Specifically, MT6250 consist of the following subsystems:
General
Integrated voice -band, audio-band and base-band analog front-end
Integrated full -featured power management unit
MCU subsystem
ARM7EJ -STM 32-bit RISC processor
Java hardware acceleration for fast Java -based games and applets
Operating fr equency: Max. 260MHz with dynamic clock gating
High -performance multi-layer AHB bus
Dedicated DMA bus with 17 DMA channels
On -chip boot ROM for factory flash programming
Watchdog timer for system crash recovery
4 sets of general -purpose timers
Circuit switch data coprocessor
Division coprocessor
Serial flash interfaces
Supports various operating frequency combinations for serial flash
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Supports QPI and SPI serial flash
User interfaces
8 -row × 8-column and 5-row x 5-column keypad controller with hardware scanner
Supports multiple key presses for gaming
Dual SIM/USIM controller with hardware T = 0/T = 1 protocol control
Real -time clock (RTC) operating with a low-quiescent-current power supply
General -purpose I/Os (GPIOs) available for auxiliary applications
1 sets of Pulse Width Modulation (PWM) output
13 external interrupt lines
1 external channel auxiliary 10 -bit A/D converter
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p
MIC input
Earphone MIC input
Receiver out
Earphone audio output
Speaker output
USB communicate bus
Keypad scan bus
TORCH enable
UART download channel
ut
2.2 Baseband Chip Pin Descriptions
2.2.1 MCU Subsystem
I2C communicate bus
T-Flash memory channel
Figure 2-2: CPU U100F MCU part
* UART----Universal Asynchronous
receiver or transmitter
Camera control
and data channel
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MCU Subsystem
ARM7EJ -STM 32-bit RISC processor
Java hardware acceleration for fast Java -based games and applets
Operating frequency : Max. 260MHz with dynamic clock gating
High -performance multi-layer AHB bus
Dedicated DMA bus with 17 DMA channels
On -chip boot ROM for factory flash programming
Watchdog timer for system crash recovery
4 sets of general -purpose timers
C ircuit switch data coprocessor
Division coprocessor
A main 32-bit ARM7EJ-S RISC processor, which plays the role of the main bus master
controlling the whole subsystem. All processor transactions go to code cache first. The code
cache controller accesses TCM (memory dedicated to ARM7EJS core), cache memory, or bus
according to the processor’s request address. If the requested content is found in TCM or in
cache, no bus transaction is required. If the code cache hit rate is high enough, bus traffic
can be effectively reduced and processor core performance maximized. The bus comprises
of two-level system buses: Advanced High-Performance Bus (AHB) and Advanced Peripheral
Bus (APB). All bus transactions originate from bus masters, while slaves can only respond to
requests from bus masters. Before data transfer can be established, the bus master must ask
for bus ownership, accomplished by request-grant handshaking protocol between masters and
arbiters. Two levels of bus hierarchy are designed to provide optimum usage for different
performance requirements. Specifically, AHB Bus, the main system bus, is tailored toward
high-speed requirements and provides 32-bit data path with multiplex scheme for bus
interconnections. The APB Bus, on the other hand, is designed to reduce interface complexity
for lower data transfer rate, and so it is isolated from high bandwidth AHB Bus by APB
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Bridge. APB Bus supports 16-bit addressing and both 16-bit and 32-bit data paths. APB
Bus is also optimized for minimal power consumption by turning off the clock when there is no
APB bus activity. During operation, if the target slave is located on AHB Bus, the transaction
is conducted directly on AHB Bus. However, if the target slave is a peripheral and is attached
to the APB bus, then the transaction is conducted between AHB and APB bus through the use
of APB Bridge. In order to off-load the processor core, a DMA Controller is designated to act
as a master and share the bus resources on AHB Bus to do fast data movement between
modules. This controller comprises thirteen DMA channels. The Interrupt Controller provides
a software interface to manipulate interrupt events. It can handle up to 32 interrupt sources
asserted at the same time. In general, it generates 2 levels of interrupt requests, FIQ and IRQ,
to the processor. A SRAM is provided for acting as system memory for high-speed data access.
For factory programming purpose, a Boot ROM module is used. These two modules use the
same Internal Memory Controller to connect to AHB Bus.
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LCM control channel
LCM data bus
2.2.2 External Memory
EM serial Control & Data channel
Figure 2-3: CPU U100C External Memory part
Serial Flash Interfaces
Supports various operating frequency combinations for Serial Flash
Supports QPI and SPI Serial Flash
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Flash memory IC description
Figure 2-4: Flash memory
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2.2.3 Camera Subsystem
Camera data channel
Camera I2C
channel
Camera vertical reference signal input
Camera clock input
Camera horizontal reference signal input
Figure 2-5: camera socket circuit
Figure 2-6: Camera processor part
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2.2.4 Audio process Subsystem
Using a highly integrated mixed-signal audio front-end, the MT6250 architecture
provides easy audio interfacing with direct connection to the audio transducers. The
audio interface integrates A/D converters for voice band, as well as high-resolution
stereo D/A converters for both audio and voice band.
MT6250 supports AMR codec to adaptively optimize the quality of speech and audio.
Moreover, HE-AAC codec is implemented to deliver CD-quality audio at low bit
rates.
In addition, a 850mW class-AB amplifier is also embedded to save the BOM cost
of adopting external amplifiers.
Audio circuit description
Figure 2-7: Handset Receiver output
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Figure 2-8: MIC circuit of Headset
Figure 2-9: Audio circuit of Handset MIC
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Figure 2-10: Ring tong circuit
Headset detect
Headset receiver
FM antenna
Headset MIC
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Figure 2-12: Audio subsystem Block diagram
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2.2.5 Power Manager
Figure 2-13: PMU subsystem Block diagram
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Charge & Power on sequence
Power on key press input , Low active
Charger-In voltage detection
Charger IC gate driver
Current sense input
SIM1 channel
SIM2 channel
Figure 2-14: CPU U100C----- Power and Supply part A (Charger\PWR ON\SIM)
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Power on Sequence
The PMU handles the powering ON and OFF of the handset. There are three ways to power-on the
handset system :
1. Push PWRKEY (Pull the PWRKEY pin to the low level)
Pulling PWRKEY low is the typical way to turn on the handset. The Vcore LDO will be turned-on
first, and then Va/Vio/Vm LDOs turn-on at the same time. The supplies for the baseband are ready
and then the system reset ends at the moment when the Vcore/Va/Vio/Vm are fully turned-on to
ensure the correct timing and function. After that, baseband would send the PWRBB signal back to
PMU for acknowledgement. To successfully power-on the handset, PWRKEY should be kept low
until PMU receives the PWRBB from baseband.
2. RTC module generate PWRBB to wakeup the system
If the RTC module is scheduled to wakeup the handset at some time, the PWRBB signal will directly
send to the PMU. In this case, PWRBB becomes high at the specific moment and let PMU power-on
just like the sequence described above.This is the case named RTC alarm.
3. Valid charger plug-in (CHRIN voltage is within the valid range)
Charger plugging-in will also turn on the handset if the charger is valid (no OVP take place).
However, if the battery voltage is too low to power-on the handset (UVLO state), the system won’t
be turned-on by any of these three ways. In this case, charger will charge the battery first and the
handset will be powered-on automatically as long as the battery voltage is high enough.
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Battery charge
The battery charger is optimized for the Li-ion batteries. The typical charging procedure can be
divided into three phases: pre-charging, constant current mode charging, and constant voltage mode
charging. Most of the charger circuits are integrated in the PMU except for one PMOS, one diode
and one accurate resistor for current sensing. These components should be applied externally.
Charge circuit description (U250)
1. Charge Detection
Figure 2-15: charging circuit part
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The PMU charger block has a detection circuit that senses the charger plug-in/out and
provides the correct information to the baseband. If CHRIN is over 4.3V, charger detection will be
report to baseband and charger circuit will be enabled. If the CHRIN voltage is over 7V, charger will
send an invalid signal to baseband for further indication. The stop of charging when CHRIN is over
7V could be achieved by external component.
2. Pre-Charging mode
When the battery voltage is below the CC threshold, the charging status is in the pre-charging
mode. There are two steps in this mode. While the battery voltage is deeply discharged below 2.7V,
a 50mA trickle current is used for charging the battery. This is the pre-CC1 state. When the battery
voltage exceeds 2.7V, the self-calibrated pre-charge mode is enabled, which allows 20mV (typically)
voltage drop across the external current sense resistor. This is the pre-CC2 state.
3. Constant Current Charging Mode
Once the battery voltage has exceeded the CC threshold, a constant current is used for
periodical charging. With periodical charging, charger circuit could detect CHRIN state and battery
state in non-charging period. This is called the constant current charging mode. An up-to-800mA
constant charging current could be programmed via the register setting.
4. Constant Voltage Charging Mode
While the battery voltage reaches 4.1V, a constant current with much shorter period is used for
charging. It could allow more often full battery detection in non charging period. This is called full
voltage charging mode or constant voltage charging mode in correspondence to a linear charger.
While the battery voltage reaches 4.2V more than the pre-setting times within the limited charging
cycles, the end-of-charging process starts. It may prolong the charging and detecting period for
getting the optimized the full charging volume. This end of charging process is fully controlled by
the baseband and could be easily optimized for different battery pack.
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Dual SIM circuit description
Figure 2-15: SIM interface block diagram
Only first SIM interface will be described in this document. The SIMVCC is used to control
the external voltage supply to the SIM card and SIMSEL determines the regulated smart card supply
voltage. SIMRST is used as the SIM card reset signal. Besides, SIMDATA and SIMCLK are used
for data exchange purpose. Basically, the SIM interface acts as a half duplex asynchronous
communication port and its data format is composed of ten consecutive bits: a start bit in state Low,
eight information bits, and a tenth bit used for parity checking. The data format can be divided into
two modes as follows:
Figure 2-16: SIM circuit diagram
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LDO output Manager
LCM backlight control
Keypad backlight control
Vibrator control
Figure 2-17: CPU U100C----- Power and Supply part B
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PAD Voltage Current Description
VCORE 1.2V 200mA Processor voltage, including MCU and DSP
VDD 2.8V 200mA Digital I/O voltage
AVDD 2.8V 100mA Analog baseband voltage
VRF 2.8V 150mA RF chip power supply
VSF 1.8V 150mA External Memory power supply
VTCXO 2.8V 40mA
VSIM_M 1.8V/3.0V 30mA
VSIM_S 1.8V/3.0V 30mA
VUSB 3.3V 100mA USB power supply
VCAMD 2.8V Camera power supply
VCAMA 1.8V Camera power supply
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2.2.6 I/O interface circuit
Software download / Media data communicate channel
Charge input
Software download / Media data switch signal
Figure 2-18: I/O interface circuit
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Chapter 3
RF Circuit Analysis
Mobile solution diagram
MT6250
Figure 3-1: RF Interface Block Diagram
Figure 3-2: IQ Signal Process Block Diagram
BAND_SW
APC
PAEN
SKY77569
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Radio interface and baseband front-end
Digital PM data path with baseband front -end
High dynamic range delta -sigma ADC converts the downlink analog I and Q signals to
digital baseband.
10 -bit D/A converter for Automatic Power Control (APC)
Programmable radio Rx filter with adaptiv e gain control
Dedicated Rx filter for FB acquisition
4 -pin Baseband Parallel Interface (BPI) with programmable driving strength
Supports multi -band
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RF receiver circuit description
PA
SKY77569
Figure 3-3: RF receiver circuit
GS900 SAW
DCS1800 SAW
CPU
MT6250
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RF transit circuit description
ANTENNA POWER PA ENABLE
BAND SWITCH(DCS)
PA
SKY77569
PA Enable
Band switch
CPU
MT6250
Figure 3-4: RF transit circuit
Auto POWER CONTROL(L10)
Power control
E-GSM IN
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y
ypa
Chapter4
TROUBLE SHOOTING
Short them by tweezer
1. Turning on failure ------ L1~L2
Fault symptoms:
no current -----check power on key & battery connector、
small current （10～30mA）------ try to download the software
large current ------ L3~L4
Check C220=VBAT
Short PWRKEY &
GND by tweezer
Check the current
Star
Dead
Y
Y
Download the
software
L3~L4
OK
N
Check if
BAT251 is OK
OK
N
Check the power on ke
N
Replace
ke
OK
N
Replace
BAT251
d
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2. Turning on failure ------ L3~L4
Case (1). No current
Check C220=VBAT
Check U100 output voltage
Star
No current
Y
Check 32.768
oscillation
Y
END
OK
N
Check if
N
BAT251 is OK
OK OK
NN
Check if the voltage
Check 32.768 & U100
OK
Replace
BAT251
on 32.768 is OK
OK
N
Replace U100
Replace 32.768 ,
N
U100
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Case (2). 10~40mA
Check U100 output
Try to download the
Star
10~40mA
voltage
Y
Check X600
oscillation
Y
software
Y
Replace U501
Y
Replace U100
END
N
OK
Replace U100
OK
N
Check X600
N
OK
Replace
OK
N
Reference the trouble shooting
of “ Download failure”
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Case (3). Large current (>130mA) ----- Large current usually cause by PA,U100
（integrate PMIC）,LDO….which directly connect to the VBAT and then shorted ,it means
the component which directly connect to VBAT was failure or the circuit wires shorted.
Another case: If the large current was appear after press power on key , it means the
external load connect to the voltage output from PMIC which one was failure.
*Warm Suggestion*
Check Rule: first small
component which be
doubted , second small IC,
third BGA chip ……
Check U100 output
voltage VDD、AVDD、
Check the voltage external load
Touch the PCBA to
Remove the component which in the
high temperature area and direct
connect to the U100 output voltage
Replace the failure
Star
Large current
VMEM…
circuit faulted
find out the high
temperature area
component
END
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3. Ring tone failure ------ L1~L2
Star
Ring tong issue
Check the user setting
N
Restore Factory Setting
Check if the speaker
contact pad is dry soldered
N
Re-solder the pad
Try to download the software
Check if the
speaker is OK
Y
N
Replace
L3~L4
Fault symptoms:
No Ring tone ----- Usually is speaker faulted ,otherwise ,L3~L4
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4. Ring tone failure ------ L3~L4
p
r
Activate the ringing circuit
“*#066*# ”choice “7 Ring
Tone”
Check the speaker is OK
Update the software
Star
Ring tong failure
Check if ring
tone sent out
from U100
N
Check U100
END
N
Y
B371 &L372
Replace
S
eake
Check on
Y
Replace Replace
N
Check on B372
&L371
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5. No display ------ L1~L2
Check if the LCM is OK
Check if the LCM
connector is dirty
Check if the LCM is dry
soldered
Try to download the software
Fault symptoms:
No display ----- Usually is the LCM faulted 、FPC faulted 、the connector dirty or dry soldered、
Software faulted.
otherwise ,L3~L4
Star
No display
L3~L4
N
Replace
N
N
Clean the connector
Re-solder the LCM
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6. No display ------ L3~L4
p
K
Star
No display
Check if LCM is OK
N
OK
Replace LCM
Y
Try to download the
software
N
Reference the trouble shooting
of “ Download failure”
Y
Check PIN 33/34
voltage
N
Check the wire between
in33/34 to U100
OK
N
Scrap
Y
Check the wires PIN
20~28 is O
Y
Check U100
N
Check out if the wire was short or open
If the wire open means the PCBA scrape
N
Replace U100
OK
END
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7. Download failure ------ L1~L2
Fault symptoms:
Download failure ----- check the cable and I/O connector, usually is the I/O connector dirty or
faulted.
otherwise ,L3~L4
Check if R273 is OK
Star
download issue
Check if cable is
OK
Y
Check if I/O
connector is OK
Y
Check U100
END
N
OK
Replace the cable
OK
N
Clean the I/O
connector
N
N
Replace
Replace
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g
8. Download failure with download Jig ------ L3~L4
If handset can power on
Check if Test Point TX
have si
Star
OK
Check if Test point
RX have signal
Y
nal
END
N
Scrap
OK
N
Check U100
Check conditions outside the mobile,
such as configuration of software,
cable, power, PC etc.
Y
Replace or re-configure
OK
N
Replace U100
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9. T-flash reader circuit failure
Fault symptoms:
T-flash connector pins shorted or bend 、Software faulted.
Check if the T-flash
connector is dirty or
Check if the pins of T-flash
socket is bend or sho rted
Try to download the
T-flash issue ----- Usually is the T-flash connector faulted
Star
T-flash circuit issue
Check if T-flash
connector is ok
N
dry soldered
N
N
software
Check U100
OK
Y
Y
Y
Replace connector
Re-solder or clean
the T-flash connector
Eliminate the shorted
、the connector dirty or dry soldered 、
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10. Dual SIM circuit failure
y
Dual SIM circuit failure
Check if SIM
connector is ok
Check if the trace on
the board is OK
Try to download the
Star
Y
Y
software
Check U100
Replace U100
END
N
N
Replace
Check if U100
dr
solder
Y
Re-solder
If the wire open means
Y
the PCBA scrape
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11. Camera circuit issue
p
Star
Camera circuit failure
Check if camera is ok
N
OK
Replace camera
OK
Check if camera
dry solder
N
Resolder the connector
Y
OK
Try to download the
software
Y
Check the power supply
on pin2#,3#,11#
N
OK
N
Check U100
Reference the trouble shooting
of “ Download failure”
Y
Check the switch signal
CMPDN
Y
Check the I2C
OK
N
check U100
OK
N
Check R440&R444 and U100
N
Replace
channel on pin4#,5#
Check the data and control
channel
N
Replace U100
END
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If the wire open means
the PCBA scra
e
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12. Call in failure----RX circuit ( L1~L2 )
Fault symptoms:
RX issue ----- Usually is the antenna pad dirty or the testing slot faulted、 Software faulted.
otherwise ,L3~L4
Star
Call in failure
Check if the
antenna pad is dirty
N
Check if the
antenna is ok
Y
N
Check if L600 is
OK
Y
Try to download the
software
L3~L4
Y
Clean the pad
Replace the antenna
N
Replace L600
R= 0
Ω
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13. Call in failure----RX circuit ( L3~L4 )
Check if U600 is ok
Try to download the
Star
Call in failure
Y
software
Y
Check Z601
Y
Check U101
END
OK
N
N
N
Replace U600
Replace U100
OK
Replace the component/IC
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14. Call out failure----TX circuit( L1~L2 )
Fault symptoms:
RX issue ----- Usually is the antenna pad dirty or the testing slot faulted、 Software faulted.
otherwise ,L3~L4
Star
Call in failure
Check if the
antenna pad is dirty
N
Check if the
antenna is ok
Y
N
Check if L600 is
OK
Y
Try to download the
software
L3~L4
Y
Clean the pad
Replace the antenna
N
Replace L600
R= 0
Ω
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15. Call out failure----TX circuit( L3~L4 )
Check if U600 is ok
Try to download the
Check U600 and control
signal: PA_EN, RF_APC
Check RF_BPI0/BANDSW
Check RF output signal on
Star
Call in failure
Y
software
Y
C305 L600
END
N
Replace U600
N
check U100
N
Replace U100
OK
OK
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Chapter6
Appendix
1.pin outs (U100)
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