Earphone Trouble - LG MG180C Service Manual

4. TROUBLE SHOOTING

4.13 Earphone Trouble

Block Diagram
HSMICP
HSO
Earphone Detecting Operation
• The ABB operates A/D conversion continuously and if the voltage of "HOOK_DETECT" node
goes to about 40mV, it detects hook switch is pushed in call state.
• First - "HOOK_DETECT" had Pull up by V_IO
• Second - "HOOk_DETECT" Change to Pull Down by Mic resistor of Earmic
Earphone Sending Path
• HSMICP is the audio signal from the microphone of the earphone.
• C221, L200 and R209 make the path of the audio signal from the microphone of the earphone.
• This audio signal is delivered to ABB(IOTA).
Earphone Receiving Path
• HSO is the audio signal from ABB(IOTA).
• C222,L202 and L201 make the path of the audio signal from ABB to earphone.
R202
(1608)
HSMICBIAS
1K
(1608)
HOOK_DETECT
C208
47p
10p NA
C218
C216 C217
47p
C221 0.1u
R209
L200 100nH
C222 10u
L202 100nH
C223
C226 47p
C227
NA
8p
Close to ABB
- 64 -
EAR-MIC
MIC
R203
10K
C206
4.7u
C205
R206 4.7u
R205
47K
5.6K
R207
1K
EVL5M02200
EVL5M02200
VA200
VA206
C219
27p
4.7
L201
C224
100nH
120p
VA207
VA201
EVL5M02200
EVL5M02200
Close to DBB Close to Ear-jack
EAR_JACK SPEC
GND
Receiver
J200
2
4
3
1
5
JACK_DETECT
R211
R212
20K
20K