Checking Flow
START
YES
Check Voltage at VBUS
of U301 = 5.0V ?
NO
Check the contact state of Data-cable
Check the voltage of the following
port at U301
VIO=2.85V?
VPU=3.3V?
YES
NO
YES
Check the soldering U301, L301
Re-soldering
U301,L301
Replace U301,L301
Replace main board.
MSM6025 is out of order
Logic level at
USB_PWR_ON/ = Low?
USB_SENSE/ = Low?
Check the signal level at R318
Is it almost 3.3v?
YES
YES
NO
NO
Check the soldering
R376,R318,R320
Re-soldering
R376,R318,R320
Replace U301
The USB interface will work properly
X200 is working?
Oscillator frequency = 48 MHz?
YES
NO
Check the soldering X200,R201
Re-soldering
X200,R201
Replace X200,R201
NO
NO
YES
YES
NO
YES
Summary of Contents for LG-YD636
Page 1: ...CDMA MOBILE SUBSCRIBER UNIT LG YD636 SINGLE BAND CDMA MOBILE PHONE SERVICE MANUAL ...
Page 16: ...3 1 5 Checking Duplexer Mobile SW Test Point Circuit Diagram U100 1 DP100 8 DP100 5 ...
Page 18: ...DP100 Pin 8 DP100 Pin 5 Graph 3 3 b Graph 3 3 c ...
Page 28: ... PM6610 FUNCTIONAL BLOCK DIAGRAM3 3 3 3 Logic Part Trouble ...
Page 36: ...Circuit Diagram USB TRANSCEIVER USB RESONATOR ...