XOCECO LC-30K9A(W), Service Manual

9 

Short introduction and working principle of    LC-30K9A(W)/LC-40K9A 

This type series of the machine set takes the form of STB plus MONITOR. Without STB, it is a 

standard computer monitor. With STB, it is a CTV receiver with powerful functions.   

For work principle flow of this series, refer to block diagram of a complete set. 

The RF signal of broadcast TV, with the help of tuner TUNA02, turns out color full TV signal TV-IN2 

and second sound IF signal. The RF signal of satellite TV with the help of BS tuner TUNA01, produces 
color full TV signal TV-BS and left and right sound signal R/L. TV video signal of TV-IN2 and TV-BS after 
the selection by PI50V330(U40-1) is sent to video decoder VPC3230(U29). The YcbCr and PCMCIA 
input from commuter board and the YUV after selection in U40-2 are also sent to U29 respectively. 
Furthermore AV1/SVHS,AV2 are also sent to U29. After the selection of above four video signals are 
subject to selection and decoding in U29 and then sent in format of 8 bi ITU-R656 to FLI2310(U13)for 
progressive treatment. One route of the video signal that is subject to selection in U29 is sent to output 
through AV.   

Two routes of D4 signal, YpbPr, after the selection in BA7657F(U11), are sent to MST9883(U30), 

where they are sent, after A/D conversion, to U13 in the format of 24 bit YUV.   

24bit RGB signal is output and sent to main processing chip JAG-ASM(U12) after the above two 

routes of signal are processed in terms of matrix, color density, and tint in U13. RGB signal of computer 
VGA is also sent to U12, where the two routes of signal are subject to selection and processing for 
picture format. One route RGB signal of VGA undergoes A/D conversion before being subject to 
selection and digit display processing together with another route of signal, including OSD, GAMMA 
calibration, brightness and contrast processing. These signals are changed into the format of 1024*768 
and output in 24 bit RGB signal. This signal is then converted into DVI signal(four pairs of differential 
signal) in SiI170 and sent to MONITOR. 

In MONITOR, four pairs of differential signal from STB are sent to PW131(N301). As there is also 

VGA input terminal in N301, the two signals, after the selection and formatting, output to output in 48bit 
RGB signal and sent to LVDS converter DS90C383(N201, N202), where they are converted to four pairs 
of low voltage differential signals and then send to LCD screen for picture display.       

The audio signal of left and right sound channels D4, YCBCR and PCMCIA undergoes selection in 

HEF4052(U34), and is then sent to MSP3420(NA04). AV1/SVHS and AV2, after  selection in 
HEF4052(U34), is sent to NA04 together with SIF of TUNA02 and R/L of TUNA01    as well as R/L of 
VGA two tuners and R/F of VGA. In NA04, SIF is demodulated into audio signal before being switched 
for selection with other four routes of R/L signal. The selected R/L after the processing in volume and 
sound effect is then output as follows: three R/L routes for left and right sound channels, one route for AV 
OUT, and another route for M62494(N203)of SRS sound field processor for SRS processing. The signal 
output to left and right sound channels is sent to MONITOR, and after sound power amplification in 
LX1722(N404), is for driving the speaker. The last route, after power amplification of earphone in 
TLE2142, is for driving the earphone.   

The power supply is through an adaptor, where it is converted to different power supplies required 

by monitor and STB.