Blu DASH 4.0 User manual

BLU DASH 4.0
SERVICE MANUAL

2013-10-16
ATTENTION
Boards, which contain Electrostatic Sensitive Device(ESD), art indicated. Following
information is ESD handling:
- 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 packages as
describe

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Contents
CONTENTS .......................................................................................................................................................................... 3
1. INTRODUCTION ............................................................................................................................................................. 4
1.1 OBJECTIVE ................................................................................................................................................................... 4
1.2 GENERAL SAFETY NOTICE ........................................................................................................................................... 4
1.3 USE INSTRUCTION........................................................................................................................................................ 4
2. TECHNOLOGY SUMMARIZE....................................................................................................................................... 5
2.1 DESCRIPTION OF MAIN BOARD COMPONENT MAP ........................................................................................................ 5
2.2 MT6572 CIRCUIT SYSTEM............................................................................................................................................ 6
2.3 BASE BAND CIRCUIT ..................................................................................................................................................... 7
3. TROUBLE SHOOTING .................................................................................................................................................. 9
3.1 FAIL TO STARTUP/POWER ON........................................................................................................................................ 9
3.2 FAIL TO CHARGE ......................................................................................................................................................... 10
3.3 FAIL TO DISPLAY.......................................................................................................................................................... 11
3.4 FAIL TO CALL............................................................................................................................................................... 12
3.5 SPEAKER NO SOUND .................................................................................................................................................. 13
3.6 EARPHONE FAIL .......................................................................................................................................................... 14
3.7 VIBRATOR FAIL............................................................................................................................................................ 15
3.8 SIDE KEY FAIL ............................................................................................................................................................. 16
3.9 FAILURE TO IDENTIFY SIM CARD................................................................................................................................ 17
3.11 CAMERA FAIL ............................................................................................................................................................ 18
3.12 FAILURE TO READ T-FLASH CARD ............................................................................................................................ 19
4. BGA RELATED GND PAD........................................................................................................................................... 20
4.1 CPU AND MEMORY PIN MAP ....................................................................................................................................... 20
4.2 PMU PIN MAP ............................................................................................................................................................. 21

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1. Introduction
1.1 Objective
The manual is not a general publication but only edited for experienced technician. The
main purpose is to provide basic foundation for the electrical & mechanical maintenance.
1.2 General Safety notice
1) Only experienced technician can repair with this guide during product is power on. Any
maintenance by other non-technicians will cause serious damage of the handset. Neither
short circuit nor counter-polarity connection is allowed for any electronic part in the
handset.
3) Be careful of ESD protection during maintenance to avoid the damage of electrostatic
sensitive components on the handset.
4) If disassembling operation is necessary for repairing, comply with mechanical structure
disassembling work instruction. Otherwise, disassembling operation will make the
handset damaged.
1.3 Use Instruction
1) Avoid using handset in conditions following:
Where there is any caustic liquid or gas
Where there is any high-temperature or fire circumstance
Where there is any flammable liquid or gas
2) Do not use handset while driving for your safety;
3) Please comply with corresponding rules in some special occasions (like in operating
room, in airplane)
4) Accessory purchasing or changing should comply with model matching;
5) If need clean handset surface, please use cloth dipping a little clean water. Do not use
soluble cleanser.

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2. Technology summarize
2.1 Description of main board component map

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2.2 MT6572 circuit system
MT6572 functional block diagram as following:
MT6572 functional system is made of three parts as below:
Digital baseband function: Memory, LCM, GPIO interface, Keypad interface etc.
Analog baseband function: AUDIO（including MIC, Receiver, Speaker）,Camera, Video,
Ambient light and Proximity sensor, Power management, RTC, Charge control, etc.
RF function: RF transceiver, GSM/WCDMA/TD communication system, etc.

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2.3 Base band circuit
MT6572 baseband System Architecture as following:
Platform Features:
◆General:
1）Smartphone,3 MCU subsystems architecture
2）eMMC boot support
3）Supports LPDDR-1/LPDDR-2/LPDDR-3/PD-DDR3
◆AP MCU subsystem
1) Dual-core ARM Cortex-A7 MP Core operating at 1.2GHz
2) NEON multimedia processing engine with SIMDv2/VFPv4 ISA support
3) 32KB L1 I-cache and 32KB L1 D-cache
4) 256KB unified L2 cache
5) DVFS technology with adaptive operating voltage from 1.05V to 1.26V
◆MD MCU subsystem
1) ARM Cortex-R4 processor with maximum 480MHz operation frequency
2) 32KB I-cache, 16KB D-cache
3) 256KB TCM (tightly-coupled memory)
4) DSP for running modem/voice tasks, with maximum 245.76MHz operation frequency
5) High-performance AXI and AHB bus
6) General DMA engine and dedicated DMA channels for peripheral data transfer
7) Watchdog timer for system error recovery
8) Power management for clock gating control
◆MD external interfaces
1) Supports dual SIM/USIM interface
2) Interface pins with RF and radio-related peripherals
3) UART for modem logging/debugging purpose

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◆External memory interface.
1) Supports LPDDR1/2/3, PC-DDR3 up to 2GB
2) 32-bit data bus width
3) Memory clock up to 333MHz
4) Supports self-refresh/partial self-refresh mode
5) Low-power operation
6) GPIOs
7) 2 sets of memory card controllers supporting SD/SDHC/MS/MSPRO/MMC and
SDIO2.0/3.0 protocols
◆Operating conditions
1) Core voltage: 1.15V
2) Processor DVFS voltage: 1.15V ~ 1.26V (Typ. 1.15V; sleep mode 1.05V)
3) Processor SRAM voltage: 1.15V ~ 1.26V (Typ. 1.15V; sleep mode 1.05V)
4) GPU voltage: 1.15V
5) I/O voltage: 1.8V/2.8V/3.3V
6) Memory: 1.2V/1.8V/1.35V/1.5V
7) NAND: 1.8V
8) LCM interface: 1.8V
9) Clock source: 26MHz, 32.768 kHz
◆Peripherals
1) USB2.0 high-speed OTG supporting 8 Tx and 8 Rx endpoints
2) USB2.0 full-speed host
3) NAND flash controller supporting NAND bootable, iNAND2 and MoviNAND
4) 2 UART for debugging and applications
5) SPI for external device
6) 2 I2C to control peripheral devices, e.g. CMOS image sensor, LCM or FM receiver
module
7) Maximum 5 PWM channels (depending on system configuration/IO usage)
8) I2S for connection with optional external hi-end audio codec

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3. Trouble Shooting
3.1 Fail to startup/power on
The following conditions may cause boot fail: battery low, battery connector is damaged or
bad welding, components bad weld/short-circuit or damaged
First, change a fully charged battery test, still startup fail, check battery connector ok or not,
if connector damaged change a new one;
Second, connect to DC power supply, if the boot process is no current, we should check
power key solder ok or not;
Third, if the boot current is very small and cannot maintain ,connect the power on test point
to GND, then check below voltage in sequence, BBWAKEUP ，VRTC ，
VPROC(VCORE,VSRAM)，VSYS，VIO18/VEMC3V3，VA28/VIO28，VM，VUSB，VMC/VMCH,
VTCXO, RESETB ok not.
Fourth, if the current stay in 80mA, we should check the circuit around flash, when CPU
calling program from flash fail, the current will stay in 80mA, re-download the software or
change a new flash or CPU.
Fail to power on
Check if the battery
is OK.
Change
battery
Check if battery
connects solder ok
Is power key OK?
Check each power
out of PMU
Resold
connect
Change a new
power key
Re-solder or
replace U1420
Re-download
Software
OK
Y
N
N
N
N
Y
Y
Y
Y
OK
N
Y
N
Resold or replace
U1501
Resold or replace
U1200
OK
Y

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3.2 Fail to charge
Check charging circuit related component, check below information in sequence:
First, checks whether boot normal use the battery, if not check battery connector solder ok
or not;
Second, check USB connector on board solder ok or not;
Third, check T2020 whether reverse, check C2020 resistance is very big or not, check
B2020、B2021 solder ok or not;
Fourth, check U1420 solder ok or not, re-hot U1420 or change a new one.
No charge
Check battery
can power on
normal or not?
Check battery
connector related
component
Check J1702
solder OK or not?
Check T2020 &
C2020
Check B2020，
B2021 ，U1400ok or
not?
Change a new
one
Change T2020
or C2020
Change related
component
Check U1420
Hot or change
U1420
Y
N
N
N
N
N
Y
Y
Y

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3.3 Fail to display
The screen dose not shines or shows white:
First, use DC power supply to start-up, check the board whether power on normal, ensure
main board can power on normal
Second, check LCD module, change a new module, check whether can display normal,
Third, check L1850, D1850, U1850 solder ok or not
Fourth, use oscilloscope to test LCD_BACKLIGHT_EN, check it whether high, if not, check
U1200 solder ok or not, re-hot U1200 or check a new one.
No display
Is the LCM well?
Change LCM
U1850
reverse or
damaged
L1850, D1850
NC or not
Change
U1850
Add L1850 or D1850
Change or
re-solder
U1200
Change
U1200
OK
N
Y
N
Y
N
Y
Y

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3.4 Fail to call
When call with somebody, we cannot hear what he says or he cannot hear what we say:
This fail may cause by receiver or microphone fail, should to check mic or receiver
problem ，if ok, it may RF fail, if fail, we need to make sure is receiver or microphone fail.
Call 112, if cannot hear voice, it may receiver problem, check microphone related
circuit ,check B1640, B1641 , C1640, C1641, C1642, T1640, T1641 solder ok or not, if all ok,
change a new microphone, also fail, check CPU, re-hot U1200 or change a new one.
Call 112, if can hear voice, it may microphone problem, change a new receiver, check
C1631, C1632, C1633, R1631, R1632 ok or not, if ok, check CPU, re-hot U1200 or change a
new one.
Voice sending or receiving no
function
Check receiver and
mic ok or not?
Check RF
Check
Receiver or
MIC
problem？
Hot or change
new one
Y
N
Receiver
Y
N
Y
Check
Related
R, C, TVS?
Check
U1200?
Change
new
REC
Check a
new one
Rework
uncorrected
component
N
N
Hot or change
new one
Check
Related
R C TVS?
Check
U1200?
Change
new MIC
Change a
new one
Rework
uncorrected
component
MIC
Y
N
N
Y
N
Y

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3.5 Speaker no sound
First, check speaker ok or not, change a new one;
Second, check B1601, B1600, T1912, T1913 solder ok or not;
Third, check U1420, re-hot or change a new one.
No sound
Is speaker OK?
Replace
Speaker
Are B1601, B1600
NC or not?
Check T1912,
T1913 ok or not?
Check U1420
ADD B1600, B1601
Re-solder uncorrected
component
Hot or change U1420
Y
N
Y
N
N
Y
N

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3.6 Earphone fail
No sound in
earphone
Is earphone
connector OK?
Replace
earphone
Is J1620
soldering well?
Are All TVS right
direction?
Related R,
C right?
Re-solder J1620
Re-solder uncorrected
TVS
Re-solder
uncorrected R C
Y
N
N
N
Y
Y
N
Hot or
change
U1420
OK
Y

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3.7 Vibrator fail
Motor doesn’t work
Supply 3.3V for motor,
test motor can work or
not
Change a
new Motor
Check VIBR_PMU ok or
not, Check SUB PCB
reverses or not
Hot U1420 or
Change a new one
Change uncorrected
component or sub
PCB
OK
Y
N
N
Y

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3.8 Side key fail
Side key no function
Is key switch soldering
OK?
Re-solder or
change new
one
Is R1469, R1435 and
R1497, NC or not?
Check U1200
Solder 1K resistance
Re-sold or change
U1200
Y
N
Y
N
Y

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3.9 Failure to identify SIM card
SIM is not identified
Touch Pin is
clean?
Clean SIM socket
Change a new
SIM to try
Is SIM socket
good?
SIM is damaged.
Replace it
Change a new one.
Check if VSIM1/
VSIM2 are OK?
Change U1420
N
Y
N
N
Y
Y
Y
Check each signal
on SIM is OK?
Hot U1420 or change
a new one
N
N

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3.11 Camera fail
First, change a new camera module, check camera connector ok or not;
Second, check AVDD, DOVDD, if fail check U1420
Third, use oscilloscope to test I2C, CAM_RST, CAM_MCLK, CAM_PCLK, MIPI_DATA,
and MIPI_CLK. If signals abnormal check U1200, re-hot or change a new one.
Camera fail
Is camera connector
soldering well?
Re-solder or
change new
one
Check camera ok or
not?
Check AVDD
DOVDD ok or
not?
Check each signal
of Camera is ok or
not?
Change a new
camera
Check U1420
related
component
Hot U1200 or
change a new one
Y
N
N
N
Y
Y
N

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3.12 Failure to read T-flash card
First, change another T flash card, check whether T flash card bad or not
Second, check card connector solder ok or not, if fail, re-solder or change a new one
Third, check TVS reserved or not, check VDD whether normal
Fourth, test related signals, such as MCCK, MCCM0, MCDA0, MCDA1…MCDA3, if
abnormal, check U1200, re-hot or change a new one.
T-F Card is not
identified
Change a new
TF-card to test
T-F card is
damaged. Replace
it
Check T flash
card socket
ok or not?
Check TVS
reverse or not?
Re-solder it or
change new one
Solder it correct
Check VDD
OK or not?
Hot U1420 or
change new
one
Y
N
N
N
Y
Y
N
Check each
signal OK or not?
Hot U1200
or change
new one
N
N

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4. BGA related GND pad
Yellow------GND pad
4.1 CPU and memory pin map