3. TROUBLE SHOOTING
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Only for training and service purposes
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3.12 Touch troubleshooting
Touch screen is a capacitive sensor with an attached flexible PCB.
Touch connector has only sensor line (Touch IC located on Main PCB)
Touch control signals are generated by MSM8226.
If device’s other function is normal, then
replace U4100
Press PWR key to power on
Replace U7200
Another Touch Panel connect.
Touch works?
Check touch IC power on main board.
TP2(VREG_L28_2V95)
TP1(VREG_L6_1V8)
TP3, TP4 is 1.8V ?
And can you see when touch to
window, TP4 signal change high to
low?
Can you see I2C wave form?
@TP5, TP6?
Touch panel works well?
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
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