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