1508(RM-388)
Baseband Description and Troubleshooting
Nokia Customer
Care
Issue 1
Copyright © 2008 Nokia, All rights reserved
Repair Function in can not Power-on Status (refer to
PMU Circuit)
• The current status resulting ‘Power Off” could be divided into three cases: Big
current, no current, no holding current.
Case One.
Big current appears when power is fed to Vbattery or “power on” key is pressed
on the handset.
Check if the following voltages of PMU are normal: VBAT, VDD_DIG,
VDD_CORE, VDD_TXPLL, VDD_TCXO, VDD_RX, VDD_TX,
If the voltages are abnormal, check the fault reason.
.
Case Two.
If current is zero, check CN703and C1011,C1012,C1013,C1014,C1015,C1016.If
there is no power output, PMU is defective. Phone cannot be repaired and must
be replaced.
Case Three.
• Raise the voltage of PS-HOLD, and measure every output voltage of PMU, The
reference clock Power-on needed is KHZ.19.2MHZ etc.
such as :VDD_DIG,VDD_CORE,VDD_TXPLL,VDD_TCXO,VDD_RX,VDD_TX ;
• Check if the clock TCXO（19.2MHz）and RTC（32.768KHz）are normal.
• If the signals are abnormal, please check the fault reason;
• If it is normal, please check the welding of CPU and Flash and perform welding or
replacement. (Replacement includes Flash Updating).The welding of the display
panel connector should also be checked, because the shortcut of the parallel
data signal and Read & Write signal on the display panel connector will lead to
failure of CPU in invoking the programs of FLASH.
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