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