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G700-U10 Smartphone
Maintenance Manual
10 Circuit and Failure Analysis
Issue 1.0 (2013-07-22)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
58
Circuit Analysis
The TP controller U1503 detects the touch point's coordinates using the T
xx
signals (24
groups) and R
xx
signals (13 groups) and sends interrupts and the coordinates to U401 using
the I2C data bus. U1503 is powered by VDD18_PMU and VDD_CTP. U1503 connects to the
TP module through the BTB connector J1501. J1501 bears the T
xx
and R
xx
signals as well as
the TP_ID1 and TP_ID0 signals that are used to detect the module manufacturer and other
information.
Troubleshooting Process
Figure 10-30
Troubleshooting touchscreen failures
Touchscreen failure
Is the power supply
to the TP control IC
normal?
Resolder or replace U1501
Y
Is the I2C signal normal? Is
the I2C0 pull-up resistor
properly connected?
Replace the faulty components
Y
N
Replace J1501
Is the TP control IC
normal?
Resolder or replace U1503
N
Is the TP module
normal?
Replace the TP module or front
cover assembly
N
Y
Is VDD18_PMU
normal?
Y
Check U202
N
N
Y
Circuit Signals
Table 10-6
Circuit signals of this section
Signal
Description
Reference Value or Waveform
VDD_CTP
TP controller power supply
2.85 V
VDD18_PMU
TP controller power supply
1.8 V