LG MX8550, Service Manual

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- 32/148 - LG Electronics Inc.
M X8550
2. Digital/Voice Processing Part
2.1 Overview
The digital/voice processing part processes the user's commands and processes all the digital and voice signal
processing in order to operate in the phone. The digital/voice processing part is made up of a main keypad/touch
keypad/LCD, receptacle part, voice processing part, mobile station modem part, memory part, and power supply part.
2.2 Configuration
2.2.1 Keypad/LCD and Receptacle Part
This is used to transmit keypad signals to MSM6500. It is made up of a keypad backlight part that illuminates the
keypad, LCD part that displays the operation status onto the screen, and a receptacle that receives and sends out voice
and data with external sources.
2.2.2 Voice Processing Part
The voice processing part is made up of an audio codec used to convert MIC signals into digital voice signals and
digital voice signals into analog voice signals, amplifying part for amplifying the voice signals and sending them to
the ear piece, amplifying part that amplifies ringer signals coming out from MSM6500, and amplifying part that
amplifies signals coming out from MIC and transferring them to the audio processor.
2.2.3 MSM (Mobile Station Modem) 6500 Part
MSM is the core elements of CDMA terminal and carries out the functions of CPU, encoder, interleaver,
deinterleaver, Viterbi decoder, Mod/Demod, and vocoder.
2.2.4 Memory Part
The memory part is made up of a NAND Flash memory and a SDRAM for storing data.
2.2.5 Power Supply Part
The power supply part is made up of circuits for generating various types of power, used for the digital/voice
processing part.
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