Micromax Q452 User manual

Q452 L3 Service Manual

1：Technical Specifications
Particular
Remarks
Key Matrix For Flashing
NA
Chipset
MT6737
Android Version
Android M
Frequency
Quad Core, 1.1GHz LTE CAT4
Network Mode
850MHz/900MHz/1800MHz/1900MHz
3G Band
B1,B8,B5
4G Band
B3,B7,B8
ROM
16G
RAM
2G
Internal SD Card memory
10.8G
Expandable Memory
64G
Factory mode code
Press Vol-/ power key at the same time
Good Earpiece volume
32Ω± 15%
Good Loudspeaker volume
8Ω± 5%
Good MIC volume
2.2kΩ± 5%
Good Vibrator volume
30Ω± 5%
2：CAUTIONS
I. Flashing & Servicing must be undertaken by qualified personnel only.
II. Ensure all work is carried out at an anti-static workstation and that an anti-static wrist strap is worn.
III. Use only approved Tools & components as specified in the parts list.
IV. Ensure all components, modules, screws, and insulators are correctly re-fitted after servicing and
alignment
V. Ensure all cables and wires are repositioned correctly if Handset disassembled
VI. Electrostatic discharge can easily damage the sensitive components of electronic products. Therefore,
Service Centre must Adhere the precautions which mentioned above.

3. L3 Service Manual
RF 2G PA
（U1200）
（）
Flash
（U401）
CPU
（U400）
BT/WIFI/GPS/
FM
( U1300)
Receiver
Connector
（SC4/SC5）
Main camera
connector
(J1501)
P-Sensor
( U1703)
XTAL
（Y801）
Power IC
(U601)
USB
Connector
（J1804）
3/4G PA
Backlight driver
(U1401)
RF IC
（U800）
（）

1. Unable to load Software:
Solution:
First check the computer can recognize the device or not, if not, Re-load it.
Then check the USB port to master control circuit is normal or not.：format the flash and upgrade again if fail in
the Proceed of downloading.
Use a fresh data cable
Earphone
Connector
(J1601）
Switch
charge IC
(U1802)
Audio PA
(U1600)
LCD
Connector
(J800)
Front Camera
connector
(J1500)
TP
connector
(J1402)
SIM
connector
(J1800)
Side KEY
connector
(J703)
Battery
connector
(J1802)
T-Flash
connector
(J1803)
Flashlight
driver
(U1502)
Flashlight
(D1502)
SIM
connector
(J1801)
4G NET
ANT
(E1101/E1102
)
WIFI/BT/GPS
ANT
(E1300/E1301)
G-Sensor
(U1700)

Check the I/O connector soldering quality, if not , Re-sold it or change it.
Check the CPU work normally or not. Re-Solder the CPU or change it
USB
Connector
CPU
Flash

2. No power on
Solution:
Flash the handset with latest SW
Check the battery have capacity or not ,if not ,Change it
Charging with transferred to 4.0 V dc power supply to the mainboard on battery Re-soldering ,check
The mainboard work current, the normal starting current will be from 100 ma jump to light screen
Enter boot LOGO 400 ma to completely started around 500 ma, if the current not right then check
Whether has short circuit or open circuit phenomenon or not.
Check the Power IC work normally or not ,Re-Solder it or change it
The output voltage normally or not
Check the 26M crystal work normally or not ,Re-Solder it or change it
Check the CPU work normally or not, Re-Solder CPU or change it
26M
crystal
CPU
Power
IC

3. Not charging:
Solution:
Flash the handset with latest SW
Plug in the charger to check whether the machine has a charging icon, if don’t have, then check the
5V power pin of USB port connect the mainboard or not
Check the voltage of battery when charging If it reaches 4.2V, has shown in front of the
Transmission, now maybe is the battery bad so that no charging.
Check the I/O connector work well or not ,if not , Re-Solder or change it
Check the charging switch work well or not ,if not , Re-Solder or change it
Check the Power IC work normally or not, Re-Solder CPU or change it
Check the CPU work normally or not. Re-Solder the CPU or change it

I/O
connector
Power IC
Switch
Charging IC
switch IC

4. LCD / Display problem:
Solution:
Flash the handset with latest SW
Check the connect ribbon cable saddle normally or not , Re-assembly LCD.
Check the LCD connector work normally or not, Re-Solder LCD connector or change it
Check the CPU work normally or not, Re-Solder CPU or change it
.
CPU
LCD
connector

5. Touch panel is not working
Flash the handset with latest SW
Check the connect ribbon cable saddle normally or not , Re-assembly TP.
Check the TP connector work normally or not, Re-Solder TP connector or change it
Check the CPU work normally or not, Re-Solder CPU or change it
TP
connector
CPU

6. LCD backlight not on or dark
Solution:
Flash the handset with latest SW
Check the connect ribbon cable saddle normally or not , Re-assembly LCD.
Check the LCD connector work normally or not, Re-Solder LCD connector or change it
Check the Backlight IC work normally or not, Re-Solder Backlight IC or change it
Check the CPU work normally or not, Re-Solder CPU or change it
.
Backlight
IC
CPU
LCD
Connector

7. SIM not detecting:
Solution:
Flash the handset with latest SW
Check if the SIM card is obviously damaged, if yes, Replace the SIM card socket
Check if the ground impedance of each pin of the SIM card socket(except the ground pin)is low(lower than grade ),if
yes, Replace the resistor of the corresponding pin;
Check if the series resistors on each network of the SIM card have pseudo soldering ,if yes, Carry out repair soldering
of the series resistors on each signal line;
Check the Power IC normally or not, then Re-Solder Power IC or change it.
Check the CPU normally or not, then Re-Solder CPU or change it.
.
SIM
Connector
CPU
Power IC

8. SD card not detecting:
Solution:
Flash the handset with latest SW
Check if the TF card is obviously damaged, if yes, Re-Solder TF connector or change it
Check if the ground impedance of each pin of the TF card socket(except the ground pin)is low(lower than grade ),if
yes, Replace the resistor of the corresponding pin;
Check if the series resistors on each network of the TF card have pseudo soldering ,if yes, Carry out repair soldering
of the series resistors on each signal line;
Check the Power IC normally or not, then Re-Solder Power IC or change it.
Check the CPU normally or not, then Re-Solder CPU or change it.
TF
connector
Power IC
CPU

9. Front camera is not working:
Solution:
Flash the handset with latest SW
Check if the Camera is obviously damaged, if yes, Replace the Camera ;
Check if the ground impedance of each pin of the Camera connector (except the ground pin)is low(lower than
grade ),if yes, Replace the resistor of the corresponding pin;
Check if the series resistors on each network of the Camera connector have pseudo soldering ,if yes, Carry out repair
soldering of the series resistors on each signal line;
Check the PMU normally or not ,then Re-solder PMU or charge it.
Check the CPU normally or not, then Re-Solder CPU or change it.
Camera
connector
CPU
PMU

10. Rear camera is not working:
Solution:
Flash the handset with latest SW
Check if the Camera is obviously damaged, if yes, Replace the Camera ;
Check if the ground impedance of each pin of the Camera connector (except the ground pin)is low(lower than
grade ),if yes, Replace the resistor of the corresponding pin;
Check if the series resistors on each network of the Camera connector have pseudo soldering ,if yes, Carry out repair
soldering of the series resistors on each signal line;
Check the PMU normally or not, then Re-Solder PMU or charge it.
Check the CPU normally or not, then Re-Solder CPU or change it.

Camera
connector
PMU
CPU

11. MIC no sound:
Solution:
Flash the handset with latest SW
Check the MIC bad or not. then Re-Solder MIC or change it
Check the connection of main board and vice board normally or not.
Check Earphone connector also , If Earphone connector got shorted : MIC & Receiver will not work
Check the MIC work normally or not , Re-Solder the MIC or change it.
Check the LCD FPC Assembly Quality , if not ,Re-Assembly it or change it.
Check the FPC connector soldering Quality , if not ,Re-sold it or change it.
Check the power IC work normally or not. Re-Solder the power IC or change it
Check the CPU work normally or not. Re-Solder the CPU or change it
MIC
MIC FPC
connector
LCD/MIC FPC
Connector
CPU
Power IC

12. Receiver not working:
Solution:
Flash the handset with latest SW
Check the receiver bad or not, then change it.
Check the receiver circuit normally or not.

Check Earphone connector also , If Earphone connector got shorted : MIC & Receiver will not work
Check the Power IC work normally or not. Re-Solder the Power IC or change it
Check the CPU normally or not, then Re-Solder CPU or change it.
13. Speaker not working:
Solution:
Flash the handset with latest SW
Check the Speaker bad or not, else change it.
Check Earphone connector also , If Earphone connector got shorted : MIC & Receiver will not work
Check the SPK FPC soldering quality , if not ,Re-sold it or change it.
Check the Main FPC Assembly Quality , if not ,Re-Assembly it or change it.
Check the FPC connector soldering Quality ,if not ,Re-sold it or change it.
Check the Power IC work normally or not. Re-Solder the Power IC or change it
Check the CPU work normally or not. Re-Solder the CPU or change it
Receiver
Slot
CPU
Power IC

SPK Slot
FPC connector
LCD/SPK FPC
Connector
Power IC
CPU