USB not connected
whether
5V of L18 is normal;
whether grounding is
normal
Whether 3.3V, 1.8V
are normal
check
resistor to ground of
D+, D-
Change audio decode
IC PNX0101
Q8 has trouble or USB
socket has false welding
Check each DC-DC switch
circuit and peripheral elements
Check whether T1 or USB
socket pin has rosin joint
Change crystal oscillator or
capacitor on two sides
N
2. Troubleshooting process for “USB not connected” is shown in the figure .3.3.2.2:
Y
N
Figure 3.3.2.2 USB jack troubleshooting flow chart
whether
oscillation of 12M
crystal oscillator is
normal
Y
N
Y
N
Y
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Содержание X21
Страница 1: ...service manual X21 RU ...
Страница 42: ...3 L1 1 8V energy storage waveform diagram 4 LCD_CS wabeform 5 LCD_D C waveform diagram 37 ...
Страница 43: ...6 LCD_RESET 7 LCD_WR waveform diagram 8 LCD_RD waveform diagram 38 ...
Страница 44: ...9 LCD_DB0 waveform diagram 1 1 L C D _ D B 2 w a v e f o r m d i a g r a m 10 LCD_DB1 waveform diagram 39 ...
Страница 45: ...12 LCD_DB3 waveform diagram 13 LCD_DB4 waveform diagram 14 LCD_DB5 waveform diagram 40 ...
Страница 46: ...15 LCD_DB6 waveform diagram 16 LCD_DB7 waveform diagram 17 IREF waveform diagram 41 ...
Страница 47: ...18 VCOMH waveform diagram 42 ...
Страница 66: ...Chapter Cinque PCB board Circuit diagram Section One PCB board X21 PCB Board 61 ...