XOCECO LC-42R27, Service Manual

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6
Working principle analysis of the unit
The RF1 via integrative tuner TUNER1 after, the FBAS VIDEO1 and SIF is generated. The RF2 via
integrative tuner TUNER2 after, the FBAS VIDEO2 and AUDIO is generated. Video signal and
audio signal of VIDEO1,VIDEO2,AV1/SVHS1,AV2,AV3/SVHS2 and audio signal of VGA and so on,
its sent NA3 (CXA2089Q) to switch selection. The output video signal of main picture (Y/V,C) sent
N7 (TVP5160) to decode. The signal via N7 decode after, it sent 8-bit ITU-R656 format signal to
N10 (FLI2310) non-interlaced processing. It sent 24bit YUV signal to main processing control chip
N15(GM1501/1601).
The sub-picture video signal via CXA2089Q selcet after, it sent N8 (TVP5147) to decode. The signal
via N8 decode after, it sent 8-bit ITU-R656 format signal to N15 (GM1501/1601). Therein, the signal
of TUNER2 is sub-picture only.
The main-picture video signal from CXA2089Q is sent to decoder and also AV OUTPUT.
Two ways YPBPR signal via HDTV switch NA1(CBT3257C) selection after, it sent to HDTV switch
device NA15(CBT3257C) switch selection with USB signal, then sent RGB switch N4(CBT3257C)
select with RGB from pc signal, then it sent to GM1501/1601.
The HDMI via receiver N34(MST3383MB) processing after, it output RGB signal of 24bit to
GM1501/1601.
They sent to GM1501/1601 picture processing, therein YPBYP or RGB to A/D conversion after, it
and other two signal are switched selection and digital display processing, it include OSD, GAMMA
correction, brightness and contrast processing, then LVDS conversion to LCD panel display.
The SIF of tuner output signal to audio processing NA4(MSP3420),The audio of main-picture and
sub-picture via switch conversion CXA2089Q to MSP3420; the audio of two YPBPR via switch
conversion NA2(HEF4052) to MSP3420, the HDMI via MST3383MB decode to audio, it audio via
N26(CS4334) D/A conversion to MSP3420 too.
The stereo of the SIF with other four ways audio switch conversion selection to volume control and
audio processing. One way output right/left channel audio of main-picture, the signal sent SRS
processing NA5 (M62494) to SRS sound stereo processing. It via sound amplifier NA7(TPA3008D2)
to speaker; one way output right/left channel audio of sub-picture, it sent to earphone, another way
is AV OUT R/L output.
The work of whole unit is controlled by MCU, which includes GM1501/1601.