Huawei Y300 Maintenance Manual page 37

Y300 Maintenance Manual

If the Y300 fails to be powered on, observe the DC current upon startup to identify the fault.
Figure 9-5, Figure 9-6, and Figure 9-7 show the fault identification processes upon no current,
weak current, and strong current.
Figure 9-5 Fault identification process upon no current
Issue 1.0 (2013-01-24)
Strong current: After you connect the Y300 to the DC power supply and press the power
key, the DC current exceeds 300 mA.
The Y300 fails to be
powered on.
Install a simulated battery on
the Y300, connect the Y300
to the maintenance power,
press the power key, and
observe the current.
There is no current.
Are the edge
connector of the
power FPC and the
power key spring
oxidized?
N
Is the VPH_PWR voltage
normal? (The maintenance
power voltage ranges from 3.4
V to 4.2 V in normal cases.)
Y
Is the clock normal?
Y
Return the Y300 to
Huawei for repair.
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9 Principles and Failure Analysis
Y
Clean the edge
connector and spring.
N
Check the Q201 and
U201.
N
Check the X301 and
U3101 of the clock.
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