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G700-U10 Smartphone
Maintenance Manual
Circuit Analysis
The TP controller U1503 detects the touch point's coordinates using the Txx signals (24
groups) and Rxx 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 Txx and Rxx 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
Circuit Signals
Table 10-6 Circuit signals of this section
Signal
VDD_CTP
VDD18_PMU
Issue 1.0 (2013-07-22)
Touchscreen failure
Is the TP module
normal?
Y
Is the power supply
to the TP control IC
normal?
Y
Is VDD18_PMU
normal?
Y
Is the I2C signal normal? Is
the I2C0 pull-up resistor
properly connected?
Y
Is the TP control IC
normal?
Y
Replace J1501
Description
TP controller power supply
TP controller power supply
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
10 Circuit and Failure Analysis
N
Replace the TP module or front
cover assembly
N
Resolder or replace U1501
N
Check U202
N
Replace the faulty components
N
Resolder or replace U1503
Reference Value or Waveform
2.85 V
1.8 V
58
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