4. TROUBLE SHOOTING
- 79 -
START
Check Battery Voltage
> 3.35V ?
Push power-on key
And check the level change
of PWRKEY
Check the voltage of
The LDO outputs at U101
Logic level at KEYON of U101
= HIGH
Does it work properly?
THE PHONE WILL
POWER ON.
Charge or Change Battery
Check the contact of power key
Or dome-switch
Replace U101
VCORE=1.8V VVCXO=2.75V
VMEM=2.8V VRTC=1.8V
VEXT=2.8V VSIM=2.85V (when sim card is inserted)
VABB=2.75V VMIC=2.5V
Re-download software
The power-on procedure is
Completed. The problem may
be elsewhere.
Does it work properly?
Replace the main board
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
Checking Flow
Z3X-BOX.COM
Summary of Contents for MG300d
Page 23: ...3 TECHNICAL BRIEF 24 Figure 3 1 SKY74400 FUNCTIONAL BLOCK DIAGRAM Z 3 X B O X C O M ...
Page 83: ...4 TROUBLE SHOOTING 84 4 6 LCD Trouble EMI FILTER CN600 Test Points Z 3 X B O X C O M ...
Page 110: ...5 DOWNLOAD AND CALIBRATION 111 8 Push the START button Z 3 X B O X C O M ...
Page 111: ...5 DOWNLOAD AND CALIBRATION 112 9 Phone test Finish is shown in below screen Z 3 X B O X C O M ...
Page 112: ...6 BLOCK DIAGRAM 113 6 BLOCK DIAGRAM Z 3 X B O X C O M ...
Page 113: ... 114 Z 3 X B O X C O M ...
Page 124: ... 125 MG300d 8 PCB LAYOUT Z 3 X B O X C O M ...
Page 125: ... 126 MG300d 8 PCB LAYOUT Z 3 X B O X C O M ...
Page 137: ... 138 Z 3 X B O X C O M ...
Page 138: ... 139 Z 3 X B O X C O M ...
Page 140: ... 141 12 EXPLODED VIEW REPLACEMENT PART LIST Z 3 X B O X C O M ...
Page 141: ... 142 Z 3 X B O X C O M ...