Micromax Q427+ User manual

Q427+ L2 Service Manual

1：Technical Specifications

Particular

Remarks

Key Matrix For Flashing

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

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

Connetor

SIM

connector

Battery

connector

RF coaxial

line

Antenna

Main

FPC

LCD

connector

GPS

ANT

SPK

RFANT

T-Flash

connecto

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

Shorting

Check shorting with Multi meter

Replace PCB if found

faulty

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

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

SW failure

Flashing with latest software

Flashing

Power on Key

Key failure

Re-solder/Replace if

found faulty

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

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

Colored screen

LCD issue

Re-assembly LCD/Replace it

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

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

TP not working proper

TP issue

Re-assembly TP/Replace it

PCBA issue

Refer to L3 repair

connector

Q427+ L2 Service Manual

4：Proximity Sensor

S.NO

Possible Cause

Validation steps

Action

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

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

Key is not response

Key is fail

Change Key

SW Issue

Flash the handset with latest SW

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

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

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

I/O

connector

USB

Cable

Q427+ L2 Service Manual

8：USB

S.NO

Possible Cause

Validation steps

Action

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

Colored screen when

open front camera

Camera is issue

Re-assembly camera or Change it

PCBA fail

Change PCBA

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

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