A74 L1&L2
service manual
2
content
1、 Product introduce..………..p3-p4
2、 Disassembly guide ……….p5-p17
3、Structure parts diagram…..p18
4、 Repairing guide …………...p19-p29
3
Product introduce
4
Product introduce
Model ：
Product size：134*67*10.25
Platform：MTK6572，dual-core 1GHz
Memory： 4GB+4Gb (Nand&sdram+RAM）
System：Android 4.2
Frequency band: WCDMA：2100，GSM：900/1800MHz
Battery： 1500mAh
charger: Travel charger
USB cable: MICRO 5PIN
earphone： 3.5jack
LCD&TP： 4.5 FWVGA, Capacitance TP
Camera：0.3M and 5.0M CMOS
Support：BT2.1，WIFI，FM。
Support：3D graphics accelerator，accelerator sensor, distance sensor, light
feeling sensor。
5
Hot gun
Tweezer
Solder iron
Tommy bar
Cross Screw driver
1. Tools list
Tweezer /Cross screw driver/ Solder/Tommy bar/hot gun
Disassembly guide
6
2. Battery caver disassembly
open the battery cover
，
as the Fig. 1
Fig. 1
Disassembly guide
Battery
cover
7
3. Back caver disassembly
1） Unscrew 12 screws in back cover ，as the Fig.2；
Fig. 2
Disassembly guide
8
Fig. 3
2） Disassemble back cover with Tommy bar ，as the Fig.3；
Disassembly guide
Back
cover
SPK
9
4.Main board and front cover disassembly
1）The main components of distribution，as the fig.4；
Fig.4
Disassembly guide
Main PCBA LCD con.
Front
CAM con.
Back CAM.
USB con.
Earphoe
con.
TP con.
T card
con.
SIM con.
Main FPC
Sub PCBA
vibrator
RF cable
Battery con.
2）remove two screws and open the LCD con.& TP con. ，and remove the
volume key FPC & power key FPC as the fig.5；
10
Fig.5
Disassembly guide
TPcon.
LCDcon.
3）open the main board and remove the RF cable con. And main FPC
con..as the FIG.6
11
Fig.6
Disassembly guide
RF cable con.
Main FPC con.
Main board
remove the light sensor and camera，as the fig.7；
12
5. Front and Back camera & light sensor disassembly
Fig.7
Disassembly guide
Back
cam.
Front
Light sensor&holder
Light sensor con.
13
Fig.9
remove the Speaker camera and receiver，as the FIG.9；
7. Speaker & receiver disassembly
Disassembly guide
receiver
14
Fig.10
8. RF cable and Main FPC disassembly
Remove the RF cable and Main FPC ，as the fig.10
Disassembly guide
RF cable
Main FPC
15
Fig.11
9. Sub PCBA disassembly
remove the sub PCBA from the ，as the fig.11；
Disassembly guide
Sub PCBA
vibrator
16
Fig.12
10.MIC disassembly
Remove the MIC，as the fig.12；
Disassembly guide
MIC con.
17
Structure parts diagram
3in1 module
(LCD, TP & front cover
Back
cover
Battery
cover
Main
PCBA
sub PCBA
5M camera
0.3M camera
Main FPC
Light
sensor
Sensor
holder
receiver
SPK
RF cable
18
Repairing guide
1. LCD
a. Check if the SW is correct, otherwise to upgrade the SW;
b. Check the LCD if is ok, otherwise change a new LCD;
c. If that the LCD loose, re-assemble the LCD and test;
d. Checking the LCD connector if is ok, otherwise re-solder it or change a new one;
e. Checking the circuit around the LCD connector.
LCD
connector
19
2. Camera
a. Checking the camera is assemble ok, re-assemble the camera and test;
b. Using the good camera to do cross test, it can check if the camera is ok;
c. Checking the camera connector if is ok as below picture, otherwise to
re-solder or change a new one;
d. Checking the circuit around the camera connector.
Repairing guide
Back Camera
connector
Front Camera
connector
20
3. TP
a. Checking the SW and upgrade the SW;
b. Checking the FPC of TP and re-assemble it;
c. Using the good TP to do cross test;
d. Checking the TP connector, otherwise re-solder or change a new one;
e. Checking the circuit around the TP connector.
Repairing guide
TP Connector
21
4.Ring
a. Checking the shrapnel of speaker if is ok;
b. Checking the resistance of speaker if is ok, otherwise to change a new
one;
c. Checking the FPC if is ok;
d. Checking SPK-FPC if connector with sub-board is ok.
Repairing guide
22
5.receiver
a. Checking the shrapnel of receiver if is ok;
b. Checking the resistance of receiver if is ok, otherwise to
change a new one;
c. Checking the connector point on the main board if is ok, as
below picture;
c. Checking the receiver circuit if is ok.
Repairing guide
a. Checking the MIC and Vibrator is cold soldering, re-solder it;
b. Change the MIC and Vibrator;
c. Checking the circuit of MIC and Vibrator;
d. Checking the FPC if connect ok.
23
6.MIC and Vibrator
Repairing guide
MIC con.
a. Checking the shrapnel of earphone if is ok;
b. Checking the connector point on the main board if is ok, as below
picture;
c. Change earphone connector;
c. Checking the circuit of earphone.
24
7. Earphone
Repairing guide
earphone
a. Checking the voltage of battery if is 3.8-4.2V and connect ok;
b. Upgrade the SW;
b. Checking the power on key and circuit around it.;
25
8.No Power On
Repairing guide
Power On
a. Checking the voltage of battery if is over 3.4V;
b. Checking the charger and USB cable if is ok;
c. Checking the USB connector and circuit if is ok.
26
9.No charging
Repairing guide
USB Connector
a. Checking the connector of T –card and SIM card;
b. Change the connector of T –card and SIM card;
27
10.No SIM card and No memory card
Repairing guide
T-card
connector
SIM
Connector
a. Checking RF line if that is broken;
b. Checking RF line assemble if is ok;
28
11.Signal
Repairing guide
RF connector
Sub-board RF
connector
End
Q&A
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