Lcd Failure; Maintenance Process - Huawei P20 Maintenance Manual

4.3 LCD Failure

4.3.1 Maintenance Process

re-debug the environment.
Does the failure recur?
cosmetic defect (such
as spot defects, black
The LCD is
verification for the LCD
faulty
Replace the LCD
and ask the MQE
to analyze the
faulty LCD
2019-6-25
EML-L29V100R001 Advanced Maintenance Manual V2.1
LCD failure
Test again and
No
Yes
Is there any
The IPQC re-
Yes checks the
spots,
and damage)?
No
Is the LCD analyzes the
BTB connector
No
fastened properly?
assembly risks
Yes
Perform cross
The PCBA is
faulty
and PCBA
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?
No
Is the voltage
of the LCD backlight
LED indicator normal
(LB1704~LB1707)?
Ye
s
Is the LCD
driver voltage normal
(LB1701、LB1702)?
Ye
s
Is the
LCD I/O power VDDIO
normal (C1027)?
Ye
s
Is the
RST PWM TE signal
normal (R1723、
R1724、R1721)?
Ye
s
Is the
MIPI signal normal
(T1701~T1705)?
Ye
s
Replace U300
Report to the TE
and equipment
NTF
engineers for cause
analysis
The PQE re-
checks the
failure failure
The PQE
Re-assemble
cause to
the LCD
prevent
The PCBA process
Ye
engineers analyze the
s
cause
Check whether U1701
and peripheral small
No
components are
defective
Check whether
U1702 and peripheral
No
small components are
defective
If there are no soldering
No issues, replace defective
components
If there are no soldering
No issues, replace defective
components
If there are no soldering
No issues, replace defective
components
Huawei Confidential
INTERNAL
Replace the
LCD
Repair the area
with soldering
issues
If there are no
soldering
issues, replace
defective
components
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