XOCECO LC22K9, Service Manual

9 

Principle analysis of LC-22K9

For the working principle of LC-22K9 please refer to LC-22K9 block diagram of the complete TV set. 

Following is a short description of the signal flow: 

RF signal through an integral tuner TUNER201 produces complete color TV signal which is input, 

together with AV1/SVHS(SVHS in priority)AV2 and PCMCIA video signals, into U29  VPC3230D for 
conversion selection and decoding. Except for being decoded the selected video signal is divided in two 
routes: one is fed to AV output terminal and another route of signal to special 21 line decoder U32  
Z86229 of CCD/V-CHIP for decoding. After decoding by U32, the signal is sent back to U29 with 
R,G,B,FB format and superimposed to the original picture decoded, then sent to U13  FLI2310 in 
ITU-R656 of 8B1T format for progressive line processing. 

YPbPr signal, after analog to digital conversion by U30    MST9883 into YUV with 24BIT is also sent 

to FLI2310.   

Above two routes of signal are processed by FLI2310 for matrix, color density and tint and then 

output as RGB with 24 BIT into the main processor chip U12    JAG-ASM. There are other two routes of 
signals: one route is RGB signal of VGA for computer, another route is DV1 into RGB signal with 24 bit to 
U12 through interface of U15 TFP403/501. Three routes of signal are processed in U12 for picture 
format. Among them, one route of VGA after A/D conversion for RGB is subject to selection for 
conversion, together with other two routes, and then processed for digital display including OSD AND 
GAMMA correction, and brightness and contrast processing and changed into 1024*768 format. The 
RGB signal with 24BIT is output to the LVDS converter, U31  DS90C383A, for conversion into the 
signal format which the screen can accept, that is, three pairs of low voltage differential signal and one 
pair of time signal. And they are further sent to LCD screen for picture display. The PWM of U12 is also 
used to control the brightness of the background light. 
  The second sound IF signal SIF output from tuner is sent to sound frequency processor N201   
MSP3420; the sound frequency signal of YPRPB,DVI and PCMCIA is also sent to N201 after switching 
over and selection by switch U34  HEF4052. The AV1/SVHS,AV2 and VGA audio signal are also sent to 
N201 respectively, where the second sound IF SIF is first demodulated to the audio signal which, 
together with four way audio signal, is selected for conversion, and then further sound magnitude 
controlled and sound effect treated. The output of left and right signal R/L is divided into two routes: one 
is sent to SRS sound field processor N203    M62494 for SRS surrounding sound processing, and further 
used to drive the speaker after the D-type  sound power amplification N207  LX1722   and 
amplification of N205,N206,N208,N210  SI4532DY; the other route is used to drive earphone after 
power amplification N212  TLE2142.  
   Power is supplied from power adapter and then converted into the power required by various 
channels and circuits.