akira LCT-27PBSTP, Service Manual

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Model No.: LCT-27PBSTP.doc
Version: 1.0
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1. Analog signal flow
Antenna reception signal send to integrative tuner (contain HF and IF amplifier circuit), the
tuner is controlled the command (SDA and SCL) of the MCU N301 (M16C), select appropriate
channel to system switch, via HF amplifier and IF amplifier decode, output video signal of
2VPP and sound signal of 1VPP.
Sound signal (SCART1, 2 sound, AV sound, YPbPr, HDMI and D-SUB) via N581 HEF4052BT
(sound diverter switch) to output signal, it send to N801(MPS3410 sound processing and
volume control) switch of audio. Select right/left sound channel, their send to digital sound
amplifier N803 (TPA3008) amplify, then send to speaker.
After output video signal of tuner, SCART1 video signal and RGB signal via matched
resistance, the signal thought alone channel send to main decode IC(N101 SVP-EX52) video
switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS
level drive for LCD screen.
AV, S-Video, SCART2 video and Y/C signal thought matched resistance, the signal send to
the N506 video switch (SN74CBT3257CDR), via switching to selected signal (EX52_Y and
EX52_C) to main decode IC (N101 SVP-EX52) video switch, A/D transition, digital decode,
image scale and OSD superposition, then send to LVDS level drive for LCD screen.
D-sub and YPbPr signal thought matched resistance, the signal send to the N507 video switch
(SN74CBT3257CDR), via switching to selected signal (EX52_YUV) to main decode IC (N101
SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition,
then send to LVDS level drive for LCD screen.
2. Digital signal flow:HDMI signal thought HDMI reception chip N405 (SiI9011HDMI with
HDCP function), after receive, output digital format signal send to SVP-EX52 PIP channel
thought image scale and OSD superposition, then send to LVDS level drive for LCD screen.
The HDMI chip output audio digital format signal change to analog sound signal from N403
(CS4344 audio DA transfer chip), then N581 switched to N801 (MPS3410 sound processing
and volume control).
3. TELETEXT function
This unit adopt main decode IC N101(SVP-EX52) of Trident company, it has TELETEXT
decode function, after decoded, the teletext information in OSD display.