Partⅲ:analysis On Signal Process Flow Of Pt4216 And Key Point Test Data - Changhong Electric PT4216 Service Manual

PartⅢ:Analysis on Signal Process Flow of PT4216 and key point test data
This chapter mainly introduces receiving and process of picture and sound signal of PDP TV and
system control procedure, supply system of unit.
1. Picture signal process Flow
IF signal which is demodulated by main tuner is sent by AV board module into video decode chip UOC
decoding ,then switched with signal from AV/S jack by internal electric switch of UOCⅢ, then the output analog video
signal is sent into analog-to-digital converter TDA8759HV/8/C1 for A/D transforming to produce R、 G、 B digital signals,
format converted by GM1601/GM1501,then, GM1601/GM1501 transform the different input formats into the uniform
up-screen signal format.
The signal demodulated by sub tuner is directly sent into sub-picture video decoder SAA7115HL/V1 for video
decoding and A/D conversion，then sent into GM1601/GM1501 again to do format transforming, the output up-screen
signal is used for sub-picture display.
The alternative PC、 HDTV(YPBPR) and DVI signals are sent directly into GM1601/GM1501 for processing to
form uniform up-screen signal.
2 Sound process flow：
TV sound: RF signal is demodulated by main tuner and output SIF signal. SIF input to UOCⅢ to demodulate and
wow process. Output audio signal to dual channel class-T digital audio power amplifier IC TA2024 on power amplifier
board. At last is sent to speaker.
AV sound: audio signal from AV is sent to UOCⅢ for processing directly ,then be amplified by power amplifier IC
TA2024 to drive speaker.
PC、 DVI、 YPbPr sound: Signal is processed by UOCⅢ on main board and amplified by TA2024 on power amplifier
board after it is strobed by MC74LVX4052DR2.
3、System control process：
After connect the AC power input (we use 3 pins power jack，the GND pin must ground well).First of all ,standby
power on power board works， signal main board obtains 5V-ST power supply， then 5V-ST power is regulated to 3.3V by
U900 on main board. At this time, standby CPU PIC16F505 begin to work, and LED lamp indicates red. After user gives
key or remote on instruction, the 7
power board to turn on, AC power on panel turns on. Each group DC power on power board is normal and output
to main board. GM1501 on main board reset normally under A702 IC control, then finish system initialization.
Meanwhile finish up-screen signal control. LED indicator turns green. It is proved system control normally.
3.1、When choice VGA mode by remote control box ，GM1501 controls TDA8759 enable by I
them work in low power consumption mode， which can save power and reduce interfere。 At the moment GM1501 output
Sel_HsVs signal to set PI5V330 in VGA input channel. If there is VGA signal input, directly into GM1501
to detect and process, output is transformed to signal suitable for PDP panel. If no VGA signal input, GM1501 can't
detect horizon and vertical sync. Signal. PDP panel display PC icon at left upper corner of screen under GM1501 system
control. Other area of panel display black screen. If no input after 60 sec, it hints to enter "save power mode".At the
moment ， examines VGA signal ceaselessly， so it can be awaken automatically in VGA mode. It is said that when VGA
signal inputs, it can work normally from standby state
3.2、When in TV／AV／YCbCr mode by remote control box，GM1501 controls UOC3 by I
signal inputs， PDP panel display normally； if no video signal input， under the control of GM1501， PDP panel displays
blue background，if no signal after 15 mins，power off automatically and into standby state. It can not be awaken
automatically。
3.3、When in DVI(digital RGB) mode by remote control box，GM1501 controls TDA8759 enable by I
them work in low power consumption mode. When DVI signal inputs, display video；if no DVI signal，GM1501 can't
detect horizon and vertical sync. Signal. PDP panel display DVI icon at left upper corner of screen under GM1501
system control. Other area of panel display black screen. If no input after 60 sec, it hints to enter "save power
th
pin of PIC16F505 sends PDP-STB high level signal to control relay T802 on
24
for
Ⅲ
2
C bus，let
2
Cbus. When video
2
C bus，let