Huawei YU220, Service Manual

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YU220 service manualV1.0
2013-10-18
Huawei secrets, no dispersion without permission
1.19.3
Side key
Side key circuit：
Side key include volume key and power key
.
Up and down keys to communicate with the U301, the first rule
out side-FPC
monomer and welding no problem, consider
two resistors R1006, R1007 are OK, and then determine when pressing
the upper or lower button when the upper or lower key is shorted to
ground, if it means short-circuit the normal, not short-circuit the
problem can be determined U301 chip, the chip can be changed.
Power
button is on the U501 communication, first rule out FPC and welding
monomer no problem, consider whether short varsities, and then consider
theU501 problem can be.
1.20
Keyboard light
Keyboard light circuit：