Mobile Phone STORM (Smartphone)
Service Manual
Page
17
of 38
4.1 Power on issue analysis
Cannot Power On
Is battery normal or not?
Go recharge
battery or
replace it
Measure
U300_E5(MSM_RESIN_N),
and other output circuit
Measure the Power On current
No Current
Small Current
Large Current
Measure VBAT,
PWRKEY and 26M
CLK
Check which chip
has abnormal temp
Re-flash FW
Replace Flash
Replace the
corresponding
IC
If all normal,
resolder or
replace CPU
N
Y
Figure 4.1 Power on failure repair process
1)
Battery cannot power on
❶
Check the battery is normal or not, if the battery is broken or lower voltage, replace it;
❷
Check battery connector (J100) is normal or not, if the connector is broken, missing, disconnect,
re-solder or replace it;
❸
Check the power on switcher is normal or not, if it is abnormal, replace
it; completed all above steps, you still cannot solve this issue, please follow the next steps.
2)
No power on Current
❶
If the mobile phone can‟t powered on by battery, we can use the DC Power Supply to check the
mobile phone‟s power on current. After connect mobile phone with DC Power Supply, press
power on key, then check the current value;
❷
For No current (0mA) issue, it means power supply
circuit problem, and we can follow the product circuit diagram to check this power supply circuit