Huawei p20(eml) l09 l29v100r001 advanced maintenance manual v2.1-compressed

EML-L29V100R001 Advanced Maintenance
Manual V2.0
Prepared By: Gao Haizhen (employee ID: 00371199) Date: 2018-01-19
Reviewed By: Maintenance support Date:
Approved By: Service representatives Date:
Huawei Technologies Co., Ltd.
All rights reserved

EML-L29V100R001 Advanced Maintenance Manual V2.1 INTERNAL
2019-6-25 Huawei Confidential Page 2 of 67
Change History
Date Version Change Reason Section No. Change
Description
Author
2018-01-19 V1.0 Released the first
version.
Gao Haizhen (employee
ID: 00371199)
2018-02-27 V2.0 Updated RF-related
contents.
Chapter 4 Gao Haizhen (employee
ID: 00371199)
2018-02-27 V2.1 Updated flow chart Chapter 4 Gao Haizhen (employee
ID: 00371199)

Contents
1 Product Introduction and Specifications..................................................................................6
1.1 Product Introduction.........................................................................................................................................6
1.2 Product Specifications......................................................................................................................................6
2 Working Principles and Materials .............................................................................................8
2.1 Block Diagram .................................................................................................................................................8
2.2 Module Functions.............................................................................................................................................8
2.3 PCBA Components and BOM Information.................................................................................................... 11
2.4 Faulty Component Description ......................................................................................................................12
3 Software Maintenance Guide...................................................................................................15
3.1 Root Detection Instructions............................................................................................................................15
3.1.1 Forcibly Entering Fastboot Mode .........................................................................................................15
3.1.2 Entering Forcible Loading Mode (Forcible Update Mode) ..................................................................15
3.1.3 Detection in Fastboot Mode..................................................................................................................15
3.1.4 ADB Mode Detection (Only for Phones that Can Properly Start) ........................................................16
3.2 Software Update Guide ..................................................................................................................................17
3.2.1 Updating a Rooted Phone .....................................................................................................................17
3.2.2 Updating an Unrooted Phone................................................................................................................19
3.3 Software Log Tool..........................................................................................................................................20
3.3.1 Log Tool................................................................................................................................................20
3.3.2 Instructions for Using the Log Tool ......................................................................................................20
4 Troubleshooting ..........................................................................................................................22
4.1 Charging Failure.............................................................................................................................................22
4.1.1 Maintenance Process.............................................................................................................................22
4.1.2 Maintenance Principle...........................................................................................................................23
4.2 SIM Card Detection Failure ...........................................................................................................................25
4.2.2 Maintenance Reference Networks ........................................................................................................26
4.3 LCD Failure ...................................................................................................................................................27
4.4 Touchscreen Failure .......................................................................................................................................29
4.5 Proximity/Ambient Light Sensor Failure .......................................................................................................31
4.6 Accelerometer Failure ....................................................................................................................................33

4.7 Compass Failure.............................................................................................................................................35
4.8 Hall Sensor Failure.........................................................................................................................................37
4.9 Motor Failure .................................................................................................................................................38
4.10 Receiver Failure ...........................................................................................................................................40
4.10.1 Maintenance Process...........................................................................................................................40
4.10.2 Maintenance Principle.........................................................................................................................41
4.11 Speaker Failure.............................................................................................................................................42
4.11.1 aintenance Process ..............................................................................................................................42
4.12 Microphone Failure......................................................................................................................................43
4.13 Headset Failure.............................................................................................................................................45
4.14 Wi-Fi and Bluetooth Failure.........................................................................................................................47
4.15 GPS Failure..................................................................................................................................................49
4.16 RF Failure (CDMA).....................................................................................................................................51
4.16.1 Maintenance Process (Transmission)..................................................................................................51
4.16.2 Maintenance Principle (Transmission)................................................................................................52
4.16.3 Maintenance Process (Reception).......................................................................................................53
4.16.4 Maintenance Principle (Reception).....................................................................................................54
4.17 RF Failure (WCDMA) .................................................................................................................................55
4.17.3 Maintenance Process (Reception).......................................................................................................57
4.18 RF Failure (GSM) ........................................................................................................................................59

4.18.3 Maintenance Process (Reception) .......................................................................................................60
4.19 RF Failure (TDS/LTE) .................................................................................................................................61
4.19.3 Maintenance Process (Reception) .......................................................................................................64

1 Product Introduction and Specifications
1.1 Product Introduction
The EML is a Huawei-developed, dual card (L+G/W) dual standby single active smartphone that supports
voice services. It has the following features:
 EMUI 8.0 (compatible with Android 8.0)
 HUAWEI Kirin 970, 4x Cortex-A73 2.4 GHz+4x Cortex-A53 1.8 GHz
 5.824 inches, 1080RGBW x 2244, 16.7 M colors, 10-point touch
 3400 mAh (typical) battery capacity
 Rear camera: 12 MP+20 MP, AF, f/1.6+f/1.8 aperture, laser focusing, single-tone flash
 Front camera: 24 MP, FF, f/2.0 aperture
1.2 Product Specifications
Operating system: Huawei EMUI 8.0 (compatible with Android 8.0)
UI: Huawei EMUI 8.0
CPU: Kirin 970
CPU core: octa-core
CPU dominant frequency: 4x Cortex A73 2.36GHz+4x Cortex A53 1.8GHz
GPU: Mali-G72 MP12
Dual card dual standby single active, either card slot can be set to accommodate the primary SIM card,
nano-SIM
Browser: Huawei EMUI 8.0 browser
Screen size: 5.824 inches
Screen color: 16.7 M colors; color saturation (NTSC): 96% (typical)
Screen: negative LCD TFT screen, contrast of 1500:1 (typical)
Resolution: 2244 x 1080 pixels
Touchscreen: multi-touch sensitive screen
Gravity sensor: supported
Light sensor: supported
Proximity sensor: supported
Fingerprint sensor: supported
Hall sensor: supported

Barometer: supported
Gyroscope: supported
Compass: supported
Mode supported by NFC: card reader mode, point-to-point mode, card simulation mode (Wallet payment,
*SIM card payment, and HCE payment); *SIM cards for SIM card payment can only be in slot SIM1.
RAM: 4 GB/6 GB
ROM: 128 GB/64 GB
Audio effect: Huawei Histen
Rear camera: 20 MP (monochrome)+12 MP (RGB), f/1.6 aperture, Leica lens
Front camera: 24 MP, f/2.0 aperture, Leica lens
Sensor type: BSI CMOS
Flash: single-tone flash
Wi-Fi 802.11a/b/g/n/ac; with support for 2.4G and 5G and direct WI-FI connection
DLNA: not supported
Wi-Fi hotspot: supported
Bluetooth: Bluetooth 4.2, with support for BLE, with support for high-definition audio of aptX, aptX HD,
and LDAC
USB: USB 2.0, with support for USB network tethering, USB charging, OTG function, and DP function
Positioning: GPS/GLONASS/BeiDou
Battery: Li-Polymer battery
Battery capacity: 3400 mAh (typical)
Charging time: about 90 minutes
Data cable port: Type-C USB port
Headset jack: Type-C headset jack
SIM card type: nano-SIM card; both card slots support nano-SIM cards.
Phone size: 150.5 mm x 77.8 mm x 8.2 mm (L x W x D)
Weight: approximately 156 g (including the battery)

2 Working Principles and Materials
2.1 Block Diagram
Figure 2-1 Phone system block diagram
Fingerprint
sensor
Gravity sensor, ambient
light sensor, compass, hall
sensor, and gyroscope
Front camera
Rear
camera+flash
4lane
MIPI
SPI2
I2C
SPI3
CSI1
DDR
UFS
PCIE
UART4
I2S
Mic x 2
I2S
SIM1
SIM0
SIM SIM
SSI CLK CLK
SSI
38.4
MHz
32
kHz
RGB LED
Bluetooth
/Wi-Fi
SSI
IQ
38.4 MHz
Type-C USB
USB 3.0
USB OTG VBUS
BQ25892
charger IC
(U1603)
U1201
Buckboost
(U1201)
HI6403
Codec
(U2201)
Smart PA
(U2501)
HI6421
PMU
(U1000)
HI6363
transceiver
X 2
(U3301&U4501)
RF: FEM
Wi-Fi
Bluetooth
HI3670 SOC
(U300)
For displaying
charging status
and notification
4Lane
Dual
MIPI
CSI0&2
 TP/LCD
DSI0
38.4 MHz Vibrator
HI6422
PMU
(U1301)
38.4
MHz
DCDC
DCDC+LDO
LPDDR4X
U300_POP
DCDC
BCM43596
(U5100)
Hi6423
U1101
UFS2.1
U1400
GPS
BCM4774
U5603
GPS
UART3
Direct
charging
load switch
U1801
VBAT
SuperSwitch
USB 2.0
VBUS_CON
USB OTG
VBAT_SYS
The entire system is composed of the board, built-in battery, and mechanical parts. The board incorporates
the printed circuit board assembly (PCBA), side button FPC, main FPC, proximity sensor sub-board,
antenna sub-board, and other components such as the LCD module, camera module, motor, microphone,
speaker, and receiver. Mechanical parts include the middle cover, rear cover, main antenna,
GPS/Wi-Fi/Bluetooth antenna, and GSM antenna for the secondary SIM card.
2.2 Module Functions
Based on the logical functions, the board can be divided into four subsystems: baseband, RF, power supply,
and user ports. The following table describes the modules and units subordinated to each subsystem and
their functions.
Subsystem Module Unit Function
Baseband HI3670 Application unit
Octa-core processor, with support for function
modules, such as SD 3.0, UART, SPI, SDIO,
I2C, I2S, PCM, HSI, HSIC, MIPI, DVP, GPIO,
HDMI, USB, keypad, LPDDR4 controller,

UFS, and PWM
User port processing
unit
Manages ports of the camera, PCM, I2S, RF,
LCD, USB, UART, MIPI, GPIO, JTAG, SPI,
and keypad
Multimedia and
game engine
Provides the MPEG/JPEG hardware engine,
game engine, JAVA accelerator, and
MP3/MMS/MIDI functions.
Modem unit
Supports HSPA+, LTE-FDD, LTE-TDD,
TDS-HSPA, and dual card dual standby dual
active.
HI6421 PMU
The chip supplies power to the Hi6421 and
multiple peripheral components, including 8
buck power supplies, 29 LDOs, 1 boost, 4
LVSs, 16 HKADCs, 2 AUXDACs, the reset
circuit, the motor drive, the LED drive, the
built-in flash drive, the class-D audio PA, and
the built-in Coulombmeter.
RF
Transmission
and reception
of WCDMA
and GSM
signals
Performs the RF function of WCDMA signal
reception and transmission. This module
includes the RF chip, PMU, and peripheral
circuits.
GPS
GPS reception
module
Receives and processes GPS signals, mainly
including the BCM4752 chip and peripheral
circuits.
Bluetooth port Bluetooth module
Performs the Bluetooth baseband function, and
transmits and receives RF signals. This unit
includes the BCM4334 and peripheral circuits.
Wi-Fi port Wi-Fi module
Performs the Wi-Fi baseband and RF
transmission and reception functions. This unit
includes the Wi-Fi part of the BCM4359 chip
and peripheral circuits.
Antenna
External antenna,
internal port
components, and
antenna protection
The phone uses built-in antennas for wireless
communication, supporting WCDMA high and
low frequency bands. The EDGE+ phone
antennas include the primary antenna,
Wi-Fi/Bluetooth/GPS antenna, and GSM
antenna for the secondary card.
User port
UART port
UART4 applies to the Bluetooth, Wi-Fi, and
FM chips, while UART3 applies to the GPS
chip.
USB port
Drive, protective
circuits, and output
port components
Refers to the USB port peripheral circuit,
protective circuit, and port connector in the
SOC and MHL subsystems. The USB port is a
main data service channel for an engineering

prototype and is also used for device
commissioning and testing during the R&D
process.
SIM card ports
Power supply,
protective circuit,
and SIM card tray
Includes the SIM card tray and related
connection circuits.
Color LCD and
backlight
LCD drive,
connection method,
and backlight
control
Both the phone screen and the LCD backlight
brightness are controlled using the CABC and
LABC functions.
Speaker
Drive method,
connection method,
and speaker
components
The power of the speaker that plays polyphonic
ringtones for incoming calls can be 500 mW.
This unit features good frequency responses to
play 20 Hz to 20 kHz audio files and can also
be used as a mono speaker to play MP3 files.
Receiver
Drive method,
connection method,
and receiver-related
components
The power of the receiver for calls must be less
than 30 mW.
Microphone
Port circuit,
connection method,
and
microphone-related
components
The phone features dual built-in silicon
microphones with noise reduction.
Earphone
Headset, headset
jack circuit, and
microphone port
circuit
The phone provides a headset jack for call
output or MP3 output. The microphone is
located on the headset line to transmit the
sound to the phone.
Vibrator port
Drive method,
connection method,
and vibrator
This unit vibrates when a call is received.
Accelerometer I2C port control
The accelerometer is an auxiliary module of the
game engine.
Gyroscope I2C port control 3-axis angular rate sensor
Compass I2C port control Geomagnetic sensor
Fingerprint
sensor
SPI port control Identifies fingerprints.
Proximity
sensor
I2C port control Senses ambient light and proximity light.
Hall sensor GPIO control Senses protective cases.
Power
distribution
network and
Power distribution
network
This unit includes filtering networks and cables
for the power supply.
Backup battery PMIC charges the capacitor for maintaining the

power
management
function
management RTC current.
Power management
of board circuits
(power-on and
power-off analysis)
Mainly refers to the LDO, which manages the
power supply flexibly. The board software
manages power supplies to circuits on the
board based on service status, protocols, or
power-saving analysis to reduce power
consumption. Three channels of 32 kHz clocks
are provided.
Charging IC
Supports dynamic path management, charges
the battery while providing power, and
prioritizes power supply.
RF PMIC Provides the RF core voltage.
2.3 PCBA Components and BOM Information
The following is the PCBA component document.
PC B A
C o m p o nents i
n
EM L-L29V 100R 001
A d vanced M ai
ntenance M anual
_V 2.
0-20180227.
xl
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2.4 Faulty Component Description
The following table describes component faults.
C o m p o nent
M ai
ntenance G ui
d e i
n
EM L-L29V 100R 001
A d vanced M ai
ntenance M anual
_V 2.
0-20180227-原稿.
xl
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No. Designator Description Symptom Remarks
1 U300 SOC
U300 is the system's main control chip.
If it fails, the symptoms may vary. For
example, the phone cannot be powered
on, the system freezes, the phone
restarts repeatedly, or the phone has
various malfunctions. Replace U300
only if you are sure SOC is faulty.
Replace SOC only
when other
methods do not
work.
2 U300_POP DDR
Various stability faults may occur. For
example, the phone cannot be powered
on, restarts repeatedly, or freezes.
DDR and SOC are
bound together.
Only if you are
sure that DDR is
defective, replace
DDR.

3 U1000
Main system
PMU HI6421
Various faults may occur. For
example, various power supply faults,
or the phone cannot be powered on.
4 U1101
Sub-PMU, which
provides power
for SOC
peripheral
devices' I/O
VDD_PERI_0V75 has a power supply
fault, the phone cannot be powered on,
the system freezes, or the phone has
electricity leakage.
5 U1201 PMU buckboost The phone cannot be powered on.
6 X1201
System 38.4
MHz clock
The phone cannot be powered on.
7 U1301
PMU 6422,
which provides
power for the big
core and GPU
The phone cannot be powered on, the
system freezes or restarts, or the phone
has electricity leakage.
8 U1400
Phone ROM
UFS2.1
The phone cannot be powered on. The
main symptom is that the phone access
Com1.0 automatically after powered
on.
9 J1501 Battery holder
The phone cannot be powered on or
charged.
10 U1602
Charging
management
chip
The phone cannot be charged, the
phone has electricity leakage, or the
phone cannot be powered.
11 U1701
Backlight drive
chip
There is not backlight, and the phone
has a black screen.
The phone screen
is normal, but the
phone appears to
have a black
screen due to lack
of backlight.
12 U1702
LCD display
drive chip
There is backlight, but without display.
The phone has a black, white, or erratic
screen.
13 J1701
TP/LCD module
connector
There is a fingerprint sensor,
touchscreen, or display failure.
14 U1801
DC charging
switch
The phone cannot start SuperCharge.
15 U1901 Flash drive chip The flash cannot be turned on.
16 U1902 RGB sensor
There are issues, such as temperature
sensor failure and image color cast.
17 J2001
Rear camera
connector
The rear camera malfunctions.

18 J2002
Front camera
connector
The front camera malfunctions.
19 U2101 Super switch
There are charging failures and power
leakage that lead to power-on failures.
There is no port, and the OTG and DP
headset cannot be detected.
Because there are
too many
integrated
functions, the
interface charging
failures are
coupled easily.
Check other
components
related to the
faulty function
first.
20 U2102
DP two-way
transfer switch
The DP cannot be detected, or only one
side can be detected. The analog
headset cannot be detected.
21 U2201
Audio Codec
chip
Various audio faults may occur.
22 U2301 Motor drive chip
There are failures. For example, the
motor does not vibrate or vibrates
continuously or abnormally.
23 MIC2301
Secondary
microphone
The microphone fails, especially in the
hands-free mode.
24 U2501
Speaker smart
PA
Faults, such as noise or no sound from
the speaker, occur.
25 U2505
BST5V power
supply chip
There is an NFC failure, or
SuperCharge cannot be detected.
26 U2601/U2604 Compass The compass does not work properly.
27 U2602
Accelerometer
and gyroscope
sensor
Functions, such as step counting,
knuckle screenshot, and auto screen
rotating, are abnormal.
28 U2603
Laser
range-finding
sensor
The rear camera focuses slowly.
29 LED2601 Tricolor LED The indicator does not work.
30 U2701
Infrared control
analog switch
The infrared function fails.
31 J2802
Dual SIM card
tray
SIM cards cannot be detected.
MicroSD cards are
not supported.
32 J2901
Main FPC
connector
The phone cannot be charged, the
speaker fails, the motor fails, the
microphone fails, smart cover mode,
Check the
connection of
fastened points or

DP display, or port detection fails, or
other failures related to sub-board
functions occur.
adhered substance
first.
33 J2902
Proximity
sensor/Ambient
light sensor
The proximity sensor/ambient light
sensor malfunctions.
34 J2903
RGB tri-color
LED connector
The LED malfunctions.
35 J2904
Side button FPC
connector
The power button and volume buttons
do not work.
3 Software Maintenance Guide
3.1 Root Detection Instructions
3.1.1 Forcibly Entering Fastboot Mode
1. Connect the phone to a computer using a USB cable. Power on the phone, press and hold the power
and volume down buttons for 10s, and wait for the phone to power off.
Expected symptom: The black screen is displayed.
2. Keep pressing and holding the power and volume down buttons, and then release the buttons when the
phone enters the fastboot screen.
Expected symptom: The fastboot page is displayed. The fastboot port is displayed in the Device Manager
on the computer.
3.1.2 Entering Forcible Loading Mode (Forcible Update Mode)
1. When the phone is powered on, press and hold the power button for 10s until the phone is powered
off.
Expected symptom: The black screen is displayed.
2. Once the phone is powered off, press the power, volume up, and volume down buttons. Connect the
phone to a computer using a USB cable.
Expected symptom: The USB update screen is displayed. The ADB port and PCUI port are displayed in the
Device Manager on the computer.
3.1.3 Detection in Fastboot Mode
1. Follow the instructions in section 3.1.1 "Forcibly Entering Fastboot Mode" to enable the phone to
enter the fastboot mode. Then, connect the phone to a computer using a USB cable.
2. Run the NFF detection tool compartner.exe. The automatic detection starts. If the detection result is
locked, the phone has not been rooted. If the detection result is unlocked, the phone has been rooted.

3.1.4 ADB Mode Detection (Only for Phones that Can Properly Start)
Connect the phone to the computer using the USB cable. Run the NFF detection tool compartner.exe. The
automatic detection starts. The phone carries out the MMI test (you can skip this test by
following the on-screen instructions) before the root test. The method for displaying test
results is the same as that for displaying test results in fastboot mode.

3.2 Software Update Guide
3.2.1 Updating a Rooted Phone
After a phone is rooted, use the fastboot tool to erase all data. Then, update the board software again.
Step 1. Run the Fastboot Erase Tool. Click the button marked as 1 next to Configure file, and enter the
password huawei. Select the required .xml file from the MHA factory-level software package.

Step 2. Check the interface switch configuration. Click ADB to Fastboot to switch to the fastboot
download mode. If the driver is installed properly, a message is displayed indicating the switch success, as
shown in the following figures. After the phone switches to the fastboot mode, the screen freezes at
HUAWEI ASCEND.
Step 3. Click Totally Erase to start erasing all data from the flash memory. After the total erase, the phone
IMEI and RFNV are lost, and the phone cannot be powered on or directly updated. The phone can be
powered on after you load the factory-level software using the IDT tool.
Step 4. After the flash memory is totally erased, the phone displays a black screen and cannot be powered
on. The port is displayed below. Download the USB driver for the production line, and select VCOM to
update the phone. After the driver is updated, the HUAWEI USB COM 1.0 port is displayed in
the Device Manager on the computer.

----End
3.2.2 Updating an Unrooted Phone
Before the update, make sure that the phone has not been rooted.
1. Use the USB cable to update the phone when the phone can be properly powered on.
2. When the phone cannot be properly powered on, update it using either of the following methods:
(1) The phone can enter the forcible loading mode (For details, see section 3.1.2): Use the USB
cable to update the phone in forcible loading mode. The following table describes the
update procedure.
Update Using the USB Cable
1. Press and hold the power button for 10s until the phone is powered off.

2. Press the power button and volume up and down buttons simultaneously. Connect the phone to the
computer using the USB cable. The phone then enters forcible loading mode. The PCUI port can be
identified.
3. Download the official UPDATE.APP file and USB update tool.
4. Use the NewMultiDownloadU_1.exe tool to update the UPDATE.APP file.
(2) The phone cannot enter forcible loading mode: Enable the phone to enter fastboot mode (For
details, see section 3.1.1). Update the phone in fastboot mode. (This method is usually used by
software developers to update versions.) Wait for the phone to properly start. Update the phone
using the USB cable. If the phone cannot be powered on, update it in fastboot mode, as shown in
the following table.
Update in Fastboot Mode
1. Press and hold the power button for 10s until the phone is powered off.
2. Press and hold the power and volume down buttons simultaneously. Connect the phone to the
computer using the USB cable to forcibly enable the phone to enter fastboot mode. The fastboot port is
displayed in the Device Manager on the computer.
3. Download the official .img file. Use the fastboot burn script to burn the .img file. The burn script
updateinadb-sec.bat is attached below.
This method is used to enable the system to temporarily start so that the phone can be updated using the
USB cable. In general, you only need to burn the partition files that affect system startup during fastboot
burning. In most cases, the phone can properly start once you burn the Sec_boot.img, system.img, and
userdata.img files. The burn script updateinadb-sec.bat is attached below.
3.3 Software Log Tool
3.3.1 Log Tool
NOTE
The log tool is used by software developers to capture logs, which help them locate phone hardware and software
problems.
3.3.2 Instructions for Using the Log Tool
1. On the dialer screen, enter *#*#2846579#*#* to enter the engineering mode. Choose Project Menu >
Background Settings > DumpLog. Enable the log switch by selecting the related option. Use the log
tool to capture logs and send them to software developers.

2. Connect the phone to the computer using the USB cable. Wait until the ADB port is displayed in the
Device Manager on the computer.
3. Place the attached log tool in a directory on the computer, such as: E:logs. Click the script to capture
logs.
Access the directory and check whether logs are captured.

4 Troubleshooting
4.1 Charging Failure
4.1.1 Maintenance Process
Figure 4-1 Troubleshooting flowchart
Charging failure
Is the
battery damaged
or bulged? Is the
battery FPC
scratched?
Replace the
battery
Yes
Is the
battery connector
damaged on the
appearance?
No
Perform cross
verification. Is the
charger normal?
Replace the
charger
No
Perform cross
verification. Is the
charger normal?
Replace the
charging cable
No
Are the
voltages of VCHG_USB
and VCHG_USB_
CONN 5 V?
No
Yes
The voltage
of VCHG_USB
is 0 V and that of
VCHG_USB_CONN is 5 V.
Is a direct charger
used?
Yes
Replace
U2101
No
Do I2C6_SCL
and I2C6_SDA have
signals?
Check whether U1602 and U300 are
soldered properly. If no, re-solder them.
If yes, replace the chips
Replace the
connector
Yes
Yes
No
No
No
If the voltages are
both 0 V, check
whether the USB
connector and FPC
on the subsidiary
board are damaged.
If so, replace them
Replace U1602
Replace
U1801

4.1.2 Maintenance Principle
Figure 4-2 Charging failure maintenance principle 1

Test Item
Test Point Network Normal Standard
TP1 (no actual test point; resistance rest) VCHG_USB 5 V or 0 V
TP2 VCHG_USB_CON 5 V
TP3 (no actual test point; you can test the
pull-up resistor)
I2C6_SCL A waveform is available after
charging is enabled.
TP4 (no actual test point; you can test the
pull-up resistor)
I2C6_SDA A waveform is available
after charging is enabled.

4.2 SIM Card Detection Failure
SIM card detection
failure
Replace the SIM card
Test the SIM card
Replace the card tray
Pass
Fail
The original SIM
card is damaged
Test the SIM card
Pass
Fail
Replace the card tray
Replace the card slot
Replace the
card holder
Signal
detected
Pass
Pass
Pass Pass
Pass
Damage
found
Fail
Fail
Fail
Fail
Fail
Test the time
sequence
Software is faulty.
Try formatting the
phone
Check components
on related circuits
Check the
main chip using an X-ray
machine
Replace the main chip
Replace defective
components
Visually
inspect the card
slot
No damage
No
signal
Test GPIO_
SIMx_DET
Test the
signals of all pins
of the SIM card
holder
Test the
impedance of all
pins of the SIM
card holder

4.2.2 Maintenance Reference Networks
TP1 GPIO_205_SIM_DET Low level, 0 V
TP2 SIM0_VCC 1.8 V or 3 V
TP3 USIM0_CLK 3.75 MHz
TP4 USIM0_RST Valid at low level
TP5 USIM0_DATA Fluctuant
TP6 SIM1_VCC 1.8 V or 3 V
TP7 USIM1_CLK 3.75 MHz
TP8 USIM1_RST Valid at low level
TP9 USIM1_DATA Fluctuant

4.3 LCD Failure
LCD failure
Test again and
re-debug the environment.
Does the failure recur?
Yes
Is there any
cosmetic defect (such
as spot defects, black
spots,
and damage)?
Is the LCD
BTB connector
fastened properly?
No
Yes
Perform cross
verification for the LCD
and PCBA
The LCD is
faulty
The PCBA is
faulty
Replace the LCD
and ask the MQE
to analyze the
faulty LCD
No NTF
Report to the TE
and equipment
engineers for cause
analysis
Yes
The IPQC re-
checks the
failure
The PQE re-
checks the
failure
Replace the
LCD
No
The PQE
analyzes the
cause to
prevent
assembly risks
Re-assemble
the LCD
Check the
appearance. Use an X-ray
machine to check the PCBA.
Are there any soldering issues
on the PCBA, especially on the
BTB
connectors?
Ye
s
No
Is the voltage
of the LCD backlight
LED indicator normal
(LB1704~LB1707)?
Is the LCD
driver voltage normal
(LB1701、LB1702)?
Is the
LCD I/O power VDDIO
normal (C1027)?
Ye
s
No
If there are no soldering
issues, replace defective
components
No
Check whether
U1702 and peripheral
small components are
defective
If there are no
soldering
issues, replace
defective
components
Check whether U1701
and peripheral small
components are
defective
No
The PCBA process
engineers analyze the
cause
Repair the area
with soldering
issues
Ye
s
Ye
s
Is the
RST PWM TE signal
normal (R1723、
R1724、R1721)?
Ye
s
No
components
Is the
MIPI signal normal
(T1701~T1705)?
Ye
s
No
components
Replace U300

4.4 Touchscreen Failure
Touchscreen failure
Yes
Test again and
re-debug the environment. Does
the failure recur?
Is there
any cosmetic defect (such as
cracks)?
No
Is the BTB
connector fastened
properly?
Yes
Perform cross
verification. Is the PCBA
defective?
No
Replace the touchscreen and ask the
MQE to analyze the cause
No NTF
Report to the TE for
cause analysis
Yes
The PQE re-checks
and organizes an
analysis
Replace the
touchscreen
No
The PQE analyzes
the cause to prevent
assembly risks
Re-assemble the
touchscreen
Yes
Check the
appearance. Use an X-ray
machine to check the PCBA. Are
there any soldering issues on the PCBA,
especially on the BTB
connectors?
Yes
The PCBA process
engineers analyze the
cause
Repair the area with
soldering issues
Is the
touchscreen Vout4 power
normal (C1027)?
Yes
Are the
touchscreen interrupt
and reset signals normal
(R1722、R1726)?
No
Are components on the
circuit normal?
Yes If there are no soldering issues,
replace U300
No If there are no soldering issues,
replace defective components
No
Yes
Are the
pull-up resistor and
components on the circuit
normal?
Yes
Is the SPI signal normal
(R1711~R1714)? No
Yes
No
issues, replace U1000
Yes

4.5 Proximity/Ambient Light Sensor Failure
Light sensor failure
(automatic MMI)
Is it an l0005
failure?
Is the
touchscreen
transmittance
low?
Replace the front
cover assembly
Light sensor failure
(manual MMI)
Do the
PCBA and front cover
spring contact
properly?
Perform
cross verification. Is
the front cover assembly
normal?
Check whether the
spring is damaged
Replace the front
cover
Perform cross
normal?
Are power
VOUT18(C2901) and
VOUT24(C2902)
normal?
Replace U1000
Check whether components on the I2C0
(C2903, C2904) circuit are defective
Yes
No
Yes
No
Yes
Yes
No
Yes
No
Yes

4.6 Accelerometer Failure
Accelerometer failure
Is the sensor
calibrated using a level
instrument?
Yes
End
Yes
No
No
Calibrate the sensor using a
level instrument
Is the failure rectified
after the calibration?
Does U2602
have cosmetic defects or soldering
issues?
Replace or re-solder U2602
Yes
No
Are all the
sensors (compass, accelerometer,
and gyroscope) on the I2C0 circuit
abnormal?
Replace U2602
Yes
No
Do any
components on the I2C0
circuit have cosmetic defects or
soldering issues?
Replace or re-solder the
faulty components
No
Yes
Is the sensor power
supply normal?
If there are no
soldering issues,
replace U1000
Is the I2C0 signal normal?
If there are no
soldering issues,
replace U300
Replace the faulty
sensor
No
Yes
Yes
No

4.7 Compass Failure
Compass failure
No
Does U2604
have cosmetic defects or soldering
issues?
Replace or re-solder
U2604
Yes
No
Are all the sensors
(photoreceptor, accelerometer,
and gyroscope) on the I2C0
circuit abnormal?
Replace U2601
Yes
No
Do any
components on the I2C0
circuit have cosmetic defects or
soldering issues?
Replace or re-solder
the faulty components
No
Yes
Is the sensor
power supply normal (C2603)?
If there are no
soldering issues,
replace U1000
Is the I2C0 signal
normal (J2901)?
If there are no
soldering issues,
replace U300
Replace the faulty
sensor
No
Yes
Yes
No
Ask PCBA process
engineers to analyze
the cause
Because all sensor I2Cs are mounted to the I2C0 circuit, choose a proper network for the test.

U2604 instead of U2601is installed. A pad is shared.
Sensor I2C addresses
Sensor I2C Address
Proximity sensor/Ambient light sensor 0x39
Accelerometer/Gyroscope 0x6B and 0x6A
Compass 0x0C

4.8 Hall Sensor Failure
Perform cross verification. Is
the sub-board faulty?
Replace the antenna sub-
board
Perform cross verification. Is
the PCBA faulty
Is the power supply of
sensor_1v8 normal?
Replace U1000
Measure the interrupt signal
of the fourth pin of U200 (on
the sub-board)
Replace the SOC (U300)
Yes
No
Yes
No
Yes

4.9 Motor Failure
Motor
failure
Are the
motor and motor
cables damaged or
broken?
The motor or motor
cables are damaged,
dirty, or poorly
soldered, causing
contact problems
Perform cross verification
for the motor and PCBA to
locate the faulty component
The motor
is faulty
The PCBA
is faulty
Use a
microscope for
the check. Does the motor
circuit have cosmetic
defects?
Fail
Pass
Fail
Is the
voltage at both ends
of the motor
1.8 V?
If there are no
soldering issues,
replace U2301
Fail
Pass
Fail
Send the
motor to the
component
team or the
supplier for
analysis
Are components
missing or
deviated?
Ask PCBA
process engineers
to locate the cause

4.10 Receiver Failure
Receiver failure
Is the receiver
resistance normal (about 30
ohms)?
Replace the receiver.
Send the faulty receiver
to the manufacturer for
analysis
There is
no sound or
the sound is
too low
Noise
The receiver
foam is not in
position. Install
it again
No
Perform cross
normal?
Yes
Are
EARN and EARP
short-circuited to the ground?
Is the circuit open-
circuited?
Ask PCBA process
engineers to
analyze the cause
It is suspected that
Codec U2201 is
faulty. Replace U2201
Use an
X-ray machine for the
check. Do L2502 and L2503
have soldering
issues?
Yes
Yes
No
No
No

L2501 RCV_TEST_P Same as the resistance of a normal
board
L2502 RCV_TEST_N Same as the resistance of a normal
board

4.11 Speaker Failure
4.11.1 aintenance Process
Speaker failure
(automatic MMI)
Is the test
passed after the rear cover
is installed?
Yes
The 1 kHz single-tone speaker and
the PCB resonate to produce noise,
resulting in high THD. The test is
passed after the rear cover is
installed. Ask the audio R&D
engineers to handle the problem
No Are the
speaker dust filter
and vibration diaphragm
complete and
clean?
No
Noise
Speaker failure (manual MMI)
No sound
Is there no sound
occasionally?
Yes
The components
are improperly
installed in the
production line.
Ask the PQE to
take corrective
measures
Rplace main FPC and
subboard
Reassemble the
components
Is the impedance
between SPKOUT_P
and SPKOUT_N
normal?
No
Is the clasp of the main FPC and
subboard abnormal
Is the speaker
FPC missing or installed
improperly?
No
No
Yes
Perform cross
faulty?
Yes
Yes No
Replace the speaker
and ask the MQE to
analyze the cause
Check whether L2501 and L2502
malfunction or have open solder or
dry joint.
Are the
SPKOUT_P and SPKOUT_N
circuits on the PCBA broken or
short-circuited?
Replace U2501
Yes
I2C communication
failure, which can be
resolved using software
tolerance design
The sound is
high or low at
times
Software calibration fails.
Contact software engineers
or restore the phone to
factory settings
TP3021 SPKOUT_ P Same as the resistance of a normal board
TP3022 SPKOUT_ N Same as the resistance of a normal board

4.12 Microphone Failure
Microphone failure
Is the failure
rectified after MIC2302 is
replaced?
The microphone is
faulty. Send it to the
manufacturer for
analysis
The PCBA is faulty
Are the
A_MIC2P and A_MIC2N
circuits normal?
Check L2303,
L2304, C2325, and
C2326 in sequence
Is the
A_MICBIAS2 voltage
normal (C2321)?
If there are no
soldering issues,
replace U2201
Yes
No
No
Yes
No

4.13 Headset Failure
Headset failure
Is the headset faulty?
YES
Replace the headset
NO
Is the BTB
connector of the main FPC
fastened to the PCBA
properly?
YES
NO Perform cross
faulty?
NO
The components are
improperly installed in the
production line. Ask the PQE
to take corrective measures
NO
YES
Is the
resistance of the networks
normal?
YES
Perform cross
verification. Is the main FPC
faulty?
Replace the main FPC
NO
YES
Check the resistance of networks
HS_FB, HSR_TEST, HSL_TEST,
HS_MIC_TEST, and HS_GND_TEST
in sequence.
Replace the
corresponding resistor
or capacitor.
Is the DP HD
video normal?
YES
Replace U2201
NO
Is the USB device normal?
Replace U2102.
NO
YES
Replace U2101

LB2404 HS_FB Same as the resistance of a normal board
LB2402 HSL_TEST Same as the resistance of a normal board
LB2403 HSR__TEST Same as the resistance of a normal board
LB2401 HS_MIC_TEST Same as the resistance of a normal board
C2227 HS_GND_TEST Same as the resistance of a normal board

4.14 Wi-Fi and Bluetooth Failure
Wi-Fi failure (found in MT)
during phone assembly
Perform cross
faulty?
No Yes
Is the coaxial
cable damaged or
missing?
No
Yes
Re-fasten, replace, or
re-assemble the
coaxial cable
The phone is
incorrectly assembled
in the production line.
Ask the PQE to take
corrective measures
Replace the
front cover
Use the
tweezers to
install the edge
connector of
the antenna
Yes No
Yes
Is the
Wi-Fi antenna
missing?
Is the edge
connector of the Wi-Fi
antenna raised or not in
position?
No
Are there
obvious traces
of pressing on the edge
connector of the
Wi-Fi
antenna?
No
The antenna pins are
too low. Use the
tweezers to adjust the
antenna pins
Replace the front
cover
Yes
Is the
resistance between
the edge connector and the
spring attached over
2 ohms?
Yes
No
Replace the
front cover
Wi-Fi failure (found
in BC) during PCBA
testing
Is the
failure rectified after
the WL_EN is
enabled?
Yes
No
No
Yes
Is the
Wi-Fi chip clock
normal?
Is the power
supply normal?
Yes
Is the power
of nodes in the Wi-Fi
circuit normal?
Yes
If there are no
soldering issues,
replace U300
If there are no
soldering issues,
replace U5100
If there are no
soldering issues,
replace U5100
No
No
Check the circuit for
faulty components
LB5201 VOUT_HLDO 1.2 V
LB5204 VOUT_LNLDO_1 1.8 V
C5215 VOUT_PA3P3 3.3 V

4.15 GPS Failure
GPS failure
Perform cross
faulty?
Is the
GPS antenna
missing?
Is the GPS
antenna properly
assembled?
Replace
the rear
cover
Is the
appearance of GPS chip,
crystal oscillator clock, and components
on the GPS antenna circuit
normal?
Replace components
with abnormal
appearance
Does the
soldering of the chip and crystal
oscillator have problems under an
X-ray machine?
Replace corresponding
components
Does TCXO5601 have output? Replace TCXO5601
Is CLK32_GPS normal?
Is GPS_EN normal?
Is the power supply of
LB5601 normal?
Is the power
of each node on the circuit
normal?
Check the circuit for
faulty components
Is the GPS
antenna spring in good
contact with the
antenna?
Re-assemble
the antenna
If the
assembly is
normal,
replace the
rear cover
Replace the rear cover
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Yes
Yes
No
Replace the PCBA

C5603 VDD_1P2 1.2 V
C5606 VDD_1P1 1.1 V
C5601 VDD_TCXO 1.8 V
C5607 VDD1P8_AUX 1.8 V

4.16 RF Failure (CDMA)
4.16.1 Maintenance Process (Transmission)
CDMA RF transmission
failure
Is the failure
rectified after the related circuit is
replaced?
Are the
wired specifications
normal?
Is the RF PA power
supply normal?
Check whether the RF
connection cable is normal
and whether the antenna
spring is in good contact
End
Replace U3202
Re-solder or replace
U3401. If the signals are
still abnormal, replace
U3301
End
Yes
Yes
No
No
Yes
No
No
Yes
Yes
No
Replace U3802
Replace Z3801. If the issue
persists, replace J3802
No
Yes
Is the
failure rectified after the
software is updated to the latest
version?
Spot-check the
output RF signals of U3401
based on the non-signaling transmission of the
frequency band. Are the signals
normal?

4.16.2 Maintenance Principle (Transmission)
Signal flow in the CDMA transmission circuit: U3301 (RFIC) → U3401 (PA) → U3702 (DPDT) → Z3701
(diplexer) → J3703 (switch holder)

4.16.3 Maintenance Process (Reception)
CDMA RF reception failure
connection cable is
normal and whether the
antenna spring is in
good contact
End
Rectify transmission
exceptions in the
preceding transmitter
Replace U3901, U3802,
Z3801, and J3802 in
sequence
End
End
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Replace the modem U300
Yes
Is the failure
rectified after the related circuit
is replaced?
Is the failure
rectified after the software
is updated to the latest
version?
Spot-check
the RF signals received
before U3301 based on the non-signaling
transmission of the frequency band. Are
the signals
normal?
Is CDMA
transmission normal?
Are the RF
signals received after U3301
normal?
Are the
normal?

4.16.4 Maintenance Principle (Reception)
Signal flow in the CDMA reception circuit: U3301 (RFIC) ← U3901 (LNA) ← U3401 (FEM) ← U3702
(DPDT) ← Z3701 (diplexer) ← J3703 (diplexer) ← antenna feed point

4.17 RF Failure (WCDMA)
WCDMA RF transmission failure
End
Replace U3202
Re-solder or replace
U3501 or U3401. If the
signals are still
abnormal, replace
U3301
End
End
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Replace the DPDT of the
corresponding frequency band
Replace J3801
No
Yes
Is the failure
replaced?
Is the failure
rectified after the software is updated to
the latest version?
Spot-check
the output RF signals of U3501 or
U3401 based on the non-signaling transmission
of the frequency band. Are the signals
normal?
Is the RF PA power
supply normal?
Replace the
corresponding diplexer based on
the abnormal frequency band. Is the failure
rectified?
Are the
normal?

Signal flow in the B1/B2/B4 transmission circuit: U3301 → U3501 (MB module) → U3701 (DPDT) →
Z3701 (diplexer) → J3703 → antenna spring
Signal flow in the B5/B8 transmission circuit: U3301 → U3401 (LB module) → U3702 (DPDT) → Z3701
(diplexer) → J3703 → antenna spring

WCDMA reception failure
connection cable is
antenna spring is in
good contact
End
Rectify transmission
exceptions in the
preceding transmitter
Replace U3901, and
U3501 or U3401 in
sequence
End
End
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Replace the modem U300
Yes
Is the failure
replaced?
Are the
normal?
Is the failure
version?
Spot-check the RF
signals received before U3301 based
on the non-signaling transmission of the
normal?
Is WCDMA transmission
normal?
Are the RF signals received
after U3301 normal?

Signal flow in the B1/B2/B4 reception circuit: U3301 ← U3901 ← U3501 (MB module) ← U3701 (DPDT)
← Z3701 (diplexer) ← J3703 ← antenna spring
Signal flow in the B5/B8 reception circuit: U3301 ← U3901 ← U3401 (LB module) ← U3702 (DPDT) ←
Z3701 (diplexer) ← J3703 ← antenna spring

4.18 RF Failure (GSM)
GSM RF transmission failure
End
Follow the power supply
maintenance procedure to
rectify the failure
Replace U3401 and
U3702
End
End
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Replace U3801
Replace U3301
No
Yes
Is the failure rectified after the
related circuit is replaced?
Are the
normal?
Is the failure
the latest version?
Spot-check the
output RF signals of U3702 based on
the non-signaling transmission of the frequency
band. Are the signals
normal?
Is the RF PA power
supply normal?
Replace the
corresponding diplexers U3702 and
U3401 based on the abnormal frequency band.
Is the failure
rectified?

Signal flow in the GSM850/GSM900 transmission circuit: U3301 → U3402 → Z3401 (LPF) → U3501
(module) → U3701 (DPDT) → Z3701 (diplexer) → J3703 → antenna spring
Signal flow in the GSM1800/GSM1900 transmission circuit: U3301 → U3402 → U3401 → U3702 →
The maintenance process is the same as that for WCDMA B5/B8, WCDMA B2, and LTE B3 reception
failures.

4.19 RF Failure (TDS/LTE)
LTE RF transmission failure
End
Replace U3202
Replace U3401, U3501,
and U3701
End
End
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Replace U3801
Replace U3301
No
Yes
Is the failure rectified after the related
circuit is replaced?
Are the
normal?
Is the failure
the latest version?
Spot-check the
output RF signals of U3701, U3401, and
U3501 based on the non-signaling transmission of the
normal?
Is the RF PA power
supply normal?
Replace the filter
on the corresponding circuit based on the
abnormal frequency band. Is the failure
rectified?

The TDS and LTE transmission circuit frequency bands include the following three modules:
HB: B1/B2/B3/B4/B9/TDS34/TDS39
UHB: B7/B38/B40/B41
LB: B5/B8/B12/B17/B18/B19/B20/B26/B28
4.19.2.1 Maintenance Principle for the HB Module
Signal flow in the B1/B2/B3/B4/B9/TDS34/TDS39 transmission circuit: U3301 → U3501 → U3701 →

4.19.2.2 Maintenance Principle for the LB Module
Signal flow in the B5/B8/B12/B17/B18/B19/B20/B26/B28 transmission circuit: U3301 → U3401 →
U3702 → Z3701 (diplexer) → J3703 → antenna spring
4.19.2.3 Maintenance Principle for the UHB Module

Signal flow in the UHB B7/B38/B40/B41 transmission circuit: U3301 → U3601 → U3501 → U3701 →
Replace RF IC U3301
connection cable is
antenna spring is in good
contact
End
Re-solder the circuit
Replace U3801
End
Yes
Yes
No
No
Yes
No
No
Yes
Yes
No
LTE RF reception failure
Are the
normal?
Is the failure
version?
Is the RF switch normal?
Check the
circuit based on the abnormal
frequency band. Is the circuit
properly soldered?
Replace the
filter based on the abnormal
frequency band. Is the failure
rectified?

4.19.4.1 Maintenance Principle for the Main HB Module
Signal flow in the B1/B2/B3/B4/B9/TDS34/TDS39 reception circuit: U3301 ← U3901 ← U3501 ←
U3701 ← Z3701 (diplexer) ← J3703 ← antenna spring

4.19.4.2 Maintenance Principle for the Main LB Module
Signal flow in the B5/B8/B12/B17/B18/B19/B20/B26/B28 reception circuit: U3301 ← U3901 ← U3401
← U3702 ← Z3701 (diplexer) ← J3703 ← antenna spring

4.19.4.3 Maintenance Principle for the Main UHB Module
Signal flow in the UHB B7/B38/B40/B41 reception circuit: U3301 ← U3901 ← U3601 ← U3501 ←
U3701 ← Z3701 (diplexer) ← J3703 ← antenna spring
Emily RF
Links-International Version-V1.0.xlsx
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EM L-L29V 100R 001
A d vanced M ai
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R F A T C o m m and
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EM L-L29V 100R 001
A d vanced M ai
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