Micromax Q427+ User manual

Q427+ L2 Service Manual
1：Technical Specifications
Particular
Remarks
Key Matrix For Flashing
NA
Chipset
MT6735P
Android Version
Android 6.0
Frequency
1.3GHz
Network Mode
2G: 850MHz/900MHz/1800MHz/1900MHz
3G: B1 B8
Data Segment
GPRS, EDGE, HSPA+ 21Mbps, FDD-LTE, TDD-LTE
Rom
16G
RAM
2G
Internal SD Card memory
12G
Expandable Memory
64G
Factory mode code
Press vol+/ 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%

Q427+ L2 Service Manual
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、service Details
Main
camera
Earphone
connector
Vibrator
Charge
connector
Front
camera
SIM
connector
TP
Connetor
SIM
connector
Battery
connector
RF coaxial
line
RF
Antenna
Main
FPC
LCD
connector
GPS
ANT
SPK
RFANT
T-Flash
connecto
r
Volume
key FPC
Battery
Wifi /BT
ANT
Fingerprint
FPC

Q427+ L2 Service Manual
1. Does not power on
S.NO
Possible Cause
Validation steps
Action
1
Shorting
Check shorting with Multi meter
Replace PCB if found
faulty
2
Battery
a) Clean the 3 or 4 golden color
point(its terminals)on the battery
b) Check voltage with Multi meter
Value must be 3.7V DC or above
Replace if found faulty
3
Battery
Connector
a) Check battery connector
b) Keep Multi meter on 20V DC and
check value must be 1.5 to 3.5V DC
Re-solder/Replace if
found faulty
4
SW failure
Flashing with latest software
Flashing
5
Power on Key
Key failure
Re-solder/Replace if
found faulty
6
PCB
Suspected PCB faulty
Refer L3 repair
Side Key
Battery
connector

Q427+ L2 Service Manual
2：Display issue/No display
S.NO
Possible Cause
Validation steps
Action
1
No display
SWissue
Flash the handset with latest SW
LCD issue
Re-assembly LCD/Replace it
PCBA issue
Re-assembly PCBA/Replace it
PCBA issue
Re-Solder the LCD connector or change it
2
Colored screen
LCD issue
Re-assembly LCD/Replace it
3
Dark screen
LCD issue
Re-assembly LCD/Replace it
SWissue
Flash the handset with latest SW
LCD backlight circuit issue
Refer L3 repair
LCD backlight is set
too low by person
Reset the value of backlight
LCD
connector
LCD

Q427+ L2 Service Manual
3：Touch panel
S.NO
Possible Cause
Validation steps
Action
1
TP not working
SW Issue
Flash the handset with latest SW
TP issue
Re-assembly TP/Replace it
PCBA issue
Refer to L3 repair
PCBA issue
Re-Solder the TP connector or change it
2
TP not working proper
TP issue
Re-assembly TP/Replace it
PCBA issue
Refer to L3 repair
TP
TP
connector

Q427+ L2 Service Manual
4：Proximity Sensor
S.NO
Possible Cause
Validation steps
Action
1
Proximity sensor fail
SW Issue
Flash the handset with latest SW
Sensor holder is not
assembled well
Re-assemble the sensor holder
PCBA issue
Change PCBA
5：G-sensor
S.NO
Possible Cause
Validation steps
Action
1
G-sensor is not working
SW Issue
Flash the handset with latest SW
Set problem
Reset mobile
PCBA issue
Change PCBA
Proximity
sensor
G-sensor

Q427+ L2 Service Manual
6：Keys
S.NO
Possible Cause
Validation steps
Action
1
Key is not response
Key is fail
Change Key
SW Issue
Flash the handset with latest SW
2
The feeling of pressing
key is bad
Key soldering Quality
Solder Key again
Some dust with dome
Clean it
Key is not assembled well
Re-assemble
Side Key

Q427+ L2 Service Manual
7：Charging
S.NO
Possible Cause
Validation steps
Action
1
Cannot charge into
Adapter is fail
Change adapter
Cable is fail
Change Cable
Battery is issue
Charging or Change it
Main FPC issue
Re-assembly or Change it
I/O connector is fail
Re-Solder or Change it
2
Have charging icon, but
not charged
SW Issue
Flash the handset with latest SW
PCBA fail
Change PCBA
Battery fail
Change battery
Battery connector issue
Change battery connector
Main FPC
Battery
connector
Adapt
er
I/O
connector
USB
Cable

Q427+ L2 Service Manual
8：USB
S.NO
Possible Cause
Validation steps
Action
1
Cannot connect to PC
USB cable is fail
Change USB cable
I/O connector fail
Re-Solder or Change it
Main FPC issue
Re-assembly or Change it
PCBA fail
Change PCBA
USB
Cable
I/O
connector
Main
FPC

Q427+ L2 Service Manual
9：Front Camera
S.NO
Possible Cause
Validation steps
Action
1
Colored screen when
open front camera
Camera is issue
Re-assembly camera or Change it
PCBA fail
Change PCBA
2
Cannot turn on Rear
camera
SW issue
Flash the handset with latest SW
Camera issue
Re-assembly or Change it
Camera issue
Re-Solder or Change Camera connector
PCBA fail
Change PCBA
Front
camera