Teclast X21, Service Manual

Page: 27 / 76

3.2.10 Headphone jack circuit
1. Headphone jack circuit schematic diagram is shown in the figure 3.2.10.1:
GND
OUTR OUTL
FM_ANT
R51
0R
R58
47K
L27 106
U9
Si1912DL S
S1
1
G1
2
D2
3
S2
4
G2
5
D1
6
R52
1K R53
1K
L28 106
L29 106
R57 4.7K
C59
103
CN3
2SJ-A382-001(HP-AC)
1
4
3
5
MUTE 2
HP_VOUTR 2
HP_VOUTL 2
FM_ANT
D6
RCLAMP0504F C
1
4
2 3
6 5
Figure 3.2.10.1 Headphone jack circuit schematic diagram
2. Working principle: left and right channel audio signals outputted from PNX0101 output through
being coupled by 220uF capacitor to headphone jack circuit. Headphone jack circuit is composed by
dual MOS tube SI1912DL that controls sound output and headphone socket CN3, pin 2 and pin 5 of
SI1912DL are connected to mute circuit, after pressing MUTE button the control dual MOS tube is
cracked to cut off the output of headphone left and right channels. D6 is circuit is TVS diode array and
used to protect ESD. Ground wire of headphone is also served as the antenna input of FM module.
3.2.11 Reset circuit
1. Reset circuit supplies rest signal to PNX0101. Reset circuit schematic diagram is shown in the
figure 3.2.11.1:
R76
0R
U2
G690L263T71/R3111N252CT1
RESET
1
GND
3
VCC
2
C5
SFI0402-050E100NP
P_GND
P_GND
VCC33
/RESET 2,3
Figure 3.2.11.1 Reset circuit schematic diagram
- 22 -
2. Working principle: reset circuit is composed by reset IC G690L263 . G690L263 may output a low
level reset pulse signal with 140 millisecond pulse width to reset the player. C5 in the circuit is voltage
dependent resistor and used to protec ESD.