U8950 Maintenance Guide V1.0
10 Principles and Failure Analysis
2012-10-22
Huawei Proprietary and Confidential
72
No Display
of LCD
Y
End
Check whether
the backlights
function.
Check L1710 and
U1303.
N
N
Y
N
Repair
J1302.
Y
Return the phone to the
manufacturer for repair.
Is the problem solved after
the software is loaded?
Check whether J1302
is well soldered.
Circuit Diagram Symbols in this Section
Signal Name
Function
Test Reference Value or
Oscillogram
VREG_L12_2P85
LCD analog voltage, 2.8 V
2.85 V
VREG_S3
I/O connector digit voltage
1.8 V
MIPI_DSI_LANE2_P
Differential s
1.8 V
MIPI_DSI_LANE2_N
Differential signals –
1.8 V
MIPI_DSI_LANE1_P
Differential s
1.8 V
MIPI_DSI_LANE1_P
Differential signals –
1.8 V
LCD_RST_N
LCD power-on reset signal
1.8 V
MDP_VSYNC_P
Vertical sync (VSYNC) signal
1.8 V
LCD_ID0
Supplier ID
1.8 V
LCD_ID1
Supplier ID
1.8 V
MIPI_DSI_CLK_P
Clock differential
1.8 V
MIPI_DSI_CLK_N
Clock differential signal –
1.8 V
