U8815
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
47
Figure 9-32
Troubleshooting process for no LCD display
Is the LCD
normal after the software is
reloaded?
Is the backlight available?
Is U910 well soldered?
Re-solder U910.
No LCD display.
Return the handset to the
factory for repair.
N
Y
Y
Y
N
N
Check L1201 and U1201.
Is the
J1201connector properly
soldered?
Y
N
End
Repair J1201.
Table 9-8 describes the signals in the circuit diagram in this section.
Table 9-8
Description of the signals in the circuit diagram in this section
Signal
Description
Reference Measurement or
Wave Form
VREG_L12_2P85
LCD analog voltage
2.85
VREG_S3
I/O connector digital voltage
1.8
MIPI_DSI_LANE2_P
Differential
1.8
MIPI_DSI_LANE2_N
Differential signal-
1.8
MIPI_DSI_LANE1_P
Differential
1.8
MIPI_DSI_LANE1_P
Differential signal-
1.8
LCD_RST
LCD power-on reset signal
1.8