Earphone Trouble - LG CG225 Service Manual

4.15 Earphone Trouble

Block Diagram
EAR-MIC
Close to ABB
C251
10p
HSMICP
C254 0.1u
HSO
C255 10u
L202
(1608)
100nH
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.
• C254, C251 and L201 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).
• C255,L202,R228 and C256 make the path of the audio signal from ABB to earphone.
Close to Ear-jack
HSMICBIAS
HOOK_DETECT
C250
47p
L201 100nH
R228 C256
1K 10p
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4. TROUBLE SHOOTING
EAR_JACK SPEC
MIC Receiver
V_IO
R218
10K
R221 5.6K
R222 1K
R224
C248 C249
47p 4.7u
47K
(1608)
R225 1K
C252 C253
47p 27p
R227 4.7
L203 R229 22
100nH
C257 C258
10p 27p
GND
C247
4.7u
(1608)
2
4
3
1
5
CN201
R231
JACK_DETECT
33K R232
22K