Sanyo LCD-19XR7, Service Manual

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6
Working principle analysis of the unit
The RF signal received by antenna will be sent to tuner TUN1, then IF signal will be obtained
through high amplifier and mixed frequency, through pre-intermediate amplified by V15, then it will
be sent to acoustic surface-wave Z17 to do IF filter and get better IF characteristics, then it will be
sent to N3 (TDA4470) to do intermediate amplification, phase-locked loop VCO and synchronous
wave detection to get video signal TV-V; after pre-intermediate amplification IF will also be sent to
acoustic surface-wave Z16 to do filter at the same time, then it will be sent to TDA4470 to do
intermediate amplification and output the second sound intermediate frequency signal (TV-SIF).
The TV-V signal output from TDA4470 together with TV-SIF will be sent to main IC NS2
(MST9E19A).
Video signal and audio signal of VGA will be sent to MST9W19A, too.
Video signal of YPbPr and Video RGB of SCART1 via video switch N5(PI5V330) selection to
MST9E19A
Video V(CVBS) of SCART1 and the audio signal L/R of YPbPr and SCART1 also sent to
MST9E19A.
The main IC NS2(MST9E19A) is a high performance and fully integrated IC, which can realize
video demodulating, video switch selection, A/D and D/A conversion, interlace/de-interlace
processing, modes conversion, OSD and low-voltage differential output, ect. And it also has
functions of audio demodulation, selection, sound effect processing and MCU.
The video signal via MST9E19A processing, output 4 pairs differential signal and 1 pair clock
signal for LCD panel display. TV-V output from TDA4470 via double video amplifying, it will be sent
to SCART1 for AV-OUT.
Audio signal via MST9E19A processing will be sent to operational amplifier NV3(LM358D)
pre-amplifying, then sent to sound amplifier NV1 (R2S15102NP) amplifying to speaker. TV-SIF via
MST9E19A demodulating and sound effect processing after, it output to operational amplifier
NV2(LM358D) amplify, then sent to SCART1 for AV-OUT.