Blu DASH 3.5 User manual

DASH 3.5
SERVICE MANUAL

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 described

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 MSM7225A circuit system ..................................................................................................... 7
2.3 Base band circuit ... ................................................................................................................ 8
2.4 Power Management circuit .................................................................................................... 9
2.5 BT/FM circuit .........................................................................................................................11
2.6 RF circuit ... ............................................................................................................................11
3. Trouble Shooting ........................................................................................................................12
3.1 Fail to startup/power on ........................................................................................................12
3.2 Fail to charge ... .....................................................................................................................13
3.3 Fail to display ... .....................................................................................................................14
3.4 Fail to call ..............................................................................................................................15
3.5 Speaker no sound ... .............................................................................................................16
3.6 Earphone fail .........................................................................................................................17
3.7 Vibrator fail ............................................................................................................................19
3.8 Side key fail ...........................................................................................................................19
3.9 Failure to identify SIM card ...................................................................................................20
3.10 Failure to identify SIM card .................................................................................................20
3.11 Camera fail ..........................................................................................................................21
3.12 Failure to read T-flash card ... .............................................................................................22
4. BGA related GND or no function pad ........................................................................................23
4.1 CPU and memory pin map ...................................................................................................23
4.2 PMU pin map ... .....................................................................................................................24
4.3 BT/FM/WIFI pin map ... .........................................................................................................25

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.

2. Technology summarize
2.1 Description of main board component map

2.2 MSM7225A circuit system
MSM7225A functional block diagram as following:
MSM7225A 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 front-end module, Antenna, RF transceiver, GSM/WCDMA communication
system, etc.
2.3 Base band circuit
MSM7225A baseband System Architecture as following:
Processing features:
◆High-performance ARM CORTEX A5 800 MHz application processor :
1）ARM architecture v7
2）32 KB instruction and 32 KB data cache
3）256 KB ARM L2 cache (L2C - 310)
4）8-stage In-order pipeline with dynamic branch prediction
5）Supports the ARM and Thumb instruction sets, and Jazelle technology to enable
direct execution of Java byte-codes
◆Industry standard ARM926EJ-S 400 MHz embedded microprocessor subsystem 1)
16 KB instruction and 16 KB data cache
2) ARM version 5TEJ instructions

3) Higher performance five-stage pipeline, Harvard cached architecture
4) Higher internal CPU clock rate with on-chip cache
5) Internal watchdog and sleep timers
◆QDSP5000 350 MHz application digital signal processing (ADSP)
1) 512 KB L2 cache
◆QDSP4000 122.88 MHz modem digital signal processing (MDSP)
Memory support features
◆256 KB internal memory (IMEM) for graphics, internal functions, DSP, etc.
◆ Dual-memory buses separating the high-speed memory subsystem (EBI1) from
low-speed peripherals (EBI2) such as LCD panels
◆Enhanced EBI1 memory support: 200 MHz bus clock for DDR SDRAM ◆
EBI2 support:
1) 1.8V memory interface support
2) Support for EBI2 A-D mixed mode
3) NAND flash memory interface
4) Support for 8-bit BCH ECC
5) Boot from NAND (One NAND not supported)
6) LCD
2.4 Power Management circuit
The PM8029 device integrates all wireless handset power-management, general house -keeping,
and user-interface support functions into a single mixed-signal IC.
This mixed-signal BiCMOS device is available in the 140-pin Wafer Level Nano-Scale
Package (140 WLNSP), which includes several ground pins for electrical ground and thermal
relief.
Power management functional block diagram as following:

Power management features:
◆Linear regulated charging from an external DC charger supply ◆
Four buck switching regulators
◆One negative charge pump switching regulator
◆19 linear regulators
◆ Multiple input ADC
◆ Single sine wave and dual square wave output VCTCXO (or XO) buffers and regulator
with deglitches.
◆Clock outputs to support high-speed USB (HS-USB) and general-purpose applications
(19.2 MHz and 2.4 MHz).
◆19.2 MHz crystal oscillator for system timing
◆32.768 KHz crystal oscillator and real-time clock with alarm and coin cell backup
◆Eleven configurable GPIO pins and eight MPPs
◆Vibration motor driver with programmable output voltage
◆Up to 1 W mono-speaker class-D drivers with bypass switches ◆
Dual input, cap less output stereo headphone amplifiers
◆18 V overvoltage protection on VCHG pins
◆Dual SIM dual standby (DSDS) - level translation and deactivation management for 2 UIM
cards
◆Synchronous GSM VBAT measurements - hardware to synchronize ADC measurements

with GSM transmit pulse
◆PDM flip-flop - built-in voltage leveling and clock synchronization flip-flop
2.5 BT/FM circuit
BT/FM schematic as following:
WCN2243 integrated BT/FM function.
◆Standalone BT
1) 2.4 GHz BT transceiver
2) BT baseband processor
3) Compliant with BT core specification version 4.0(BR/EDR+BLE)
◆Standalone FM radio
1) FM transmitter/receiver
2) FM baseband processor
3) Worldwide FM band support with RDS
◆Support circuits that provide regulated supply voltages, clocks, and digital I/Os for the BT
and FM radio circuits

2.6 RF circuit
RF functional block diagram as following:
RF interface features:
◆TX output chain controls
1) Multiple CDMA and UMTS PA on/off and range controls
2) GSM PA power control
3) 14-bit generic RF controller (GRFC) interface
◆RTR6285A status and control
1) Multiple SSBIs
2) Tx enable and gain control
◆Rx/Tx analog baseband interfaces
1) Dual Rx analog baseband interfaces support CDMA and UMTS diversity Rx plus
S-GPS
2) Tx analog baseband supports all phone transmission modes
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, VREG_S1，VREG_S2，VREG_S3_SP，
VREG_L3，VREG_L7，VREG_L4，VREG_L12，VREG_L9，VREG_L14 ok not.

Fourth, if the current stay in 40mA, we should check the circuit around flash, when CPU
calling program from flash fail, the current will stay in 40mA, re-download the software or
change a new flash or CPU.
Fail to power on
N
Check if the battery Change
is OK. battery
Y
Check if battery N Resold
connects solder ok connect
Y
Is power key OK? N Change a new
power key
Y
Check each power N Re-solder or
out of PMU replace U1001
Y
Re-download Y
Software OK
N
Resold or replace Y
U502 OK
N
Y
Resold or replace OK
U0401
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 T1710 whether reverse; check C1802 resistance is very big or not.
Fourth, check U1001 solder ok or not, re-hot U1001 or change a new one.

No charge
Check battery
can power on
normal or not?
Y
Check J1702
solder OK or not?
Y
Check T1710 &
C1802
Y
Check C1008, and
R1008 ok or not?
Y
Check U1001
3.3 Fail to display
The screen dose not shines or shows white:
N Check battery
connector related
component
N
Change a new
one
N Change T1710
or C1802
N
Change related
component
N
Hot or change
U1001
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 R0004, R1177, U1501 solder ok or not
Fourth, use oscilloscope to test LCD_BACKLIGHT_EN, check it whether high, if not, check
R1507 resistance, U0401 solder ok or not, re-hot U0401or check a new one.

No display
Is the LCM well?
Y
U1501
reverse or
damaged
N
R0004, R1177
NC or not
N
Change or
re-solder
U0401
3.4 Fail to call
N
Change LCM
Y Change
U1501
Y
Add R0004 or R1177
Y Change
U0401
OK
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, it can test in factory mode,
type“*#*#7#*#*”enter factory mode, Transmitter/Receiver test, if ok, it may RF fail, if fail, we
need to make sure is receiver or microphone fail.
Call 112, if can hear voice, it may microphone problem, check microphone related
circuit ,check B1501, B1502 ,C1907,C1908,T1901,T1902 solder ok or not, if all ok, change a
new microphone, also fail, check CPU, re-hot U0401 or change a new one.

Call 112, if cannot hear voice, it may receiver problem, change a new receiver, check
R1916, R1917, C1926, C1927, C1928, C2002, V1201, V1202 ok or not, if ok, check CPU, re-
hot U0401 or change a new one.
Voice sending or receiving no
function
Can hear sound in Y
Factory mode?
N
Check RF
MIC Check Receiver
Receiver or
MIC
Y Y
Change a Change Change Check a
new one new MIC new new one
N
Rework
uncorrected
N N
N
Check Check
Related Rework
Related
R C TVS? R, C, TVS? uncorrected
Y
Y Y
N N
Hot or change Check Check Hot or change
new one U0401? U0401? new one
3.5 Speaker no sound
First, check speaker ok or not, change a new one;
Second, check B1910, B1911, T1912, T1903, C1929, C1930, C2001, solder ok or not;
Third, check U1001, re-hot or change a new one.

No sound
Is speaker OK?
Y
Are B1910, B1911
NC or not?
N
Check T1912,
T1903, C1929,
C1930, and C2001
ok or not?
Y
N
Check U1001
N Replace
Speaker
Y
ADD B1910,B1911
N Re-solder uncorrected
component
Hot or change U1001

3.6 Earphone fail
No sound in
earphone
Is earphone N
connector OK?
Y
Is J601 soldering N
well?
Y
Replace
earphone
Re-solder J601
Are All TVS right
direction?
Y
Related R,
C right?
Y
Hot or
change
U1001
N Re-solder uncorrected
TVS
N Re-solder
uncorrected R C
OK

3.7 Vibrator fail
Motor doesn’t work
3.8 Side key fail
Supply 3.3V for motor,
test motor can work or
not
Y
Check related R, C OK
or NOT, Check D1201
reverses or not
Y
Hot U1001 or
Change a new one
N Change a
new Motor
N Change uncorrected
component
OK
Side key no function
N
Is key switch soldering
OK?
Y
Is R1469, R1435, R1497,
and R1921 NC or not?
N
Check U0401
Re-solder or
change new
one
Y Solder 1K resistance
Y
Re-sold or change
U0401

3.9 Failure to identify SIM card
SIM is not identified
Touch Pin is N
clean?
Y
Change a new Y
SIM to try
N
Is SIM socket N
good?
Y
Check if VSIM1/ N
VSIM2 are OK?
Y
Check each signal N
on SIM is OK?
3.10 Failure to flash IMEI
Fail to flash IMEI
N
Could it power
on?
Y
Y
Could it
download?
N
Re-solder or N
change memory
U502.
Y
OK
Clean SIM socket
SIM is damaged.
Replace it
Change a new one.
Change U1001
Hot U1001 or change
a new one
To the part fails to power on
Re-plug USB cable,
re-flash IMEI
Re-solder or change
U0401