Huawei YU220, Service Manual

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YU220 service manualV1.0
2013-10-18
Huawei secrets, no dispersion without permission
Chapter 2 mobile principle and fault
analysis
In accordance with the following guidelines before the operation and
maintenance to ensure the phone is not a factor in environmental factors
and feature set. It recommends that you should backup customer information,
and then restore the factory settings for fault recognition.
1.4
Fail to start up.
Fault analysis treatment scheme：
For those fault phones which could not start up, please firstly check I/O
connector (battery connector) whether have apparent damage. If I/O connector
(battery connector) is OK, it can use DC stabilized power to supply power for
phone, check the current of the fault phones. No boot fault can be divided into
the boot, no current, low current, high current. In maintenance, please
according to the following specific methods for operation.
1.4.1
No current
（
direct-current main power supply
）
No current ordinary have three probable reasons：1. Battery connector dry
joint；2. Power key damage；3. Power key relevance circuit or power manage
chip damage.
Maintain flow：