XOCECO LC23K6, Service Manual

9 

LC-23K

6

 working principle analysis 

Please refer to LC-23K

6

 BLOCK DIAGRAM in order to know the working principle of LC-23K

6

 brief 

introdection to its signal flow is shown as follows: 
 
RF signal produces composite color television signal through TUNER201, the signal together with   
AV1/SVHS(SVHS priority), AV2 etc. are sent to U29 VPC3230D to decode and do switching 
selection. In addition to decode the selected video signal, part of the selected video signal is also 
sent to AV terminal and 21 line decoder U32 Z86229 which is exclusive to decode CCD/V-CHIP to 
decode. After decoded by U32, the signal will be sent back to U29 in the form of R G B and FB, then 
it will be added to the decoded picture and then it will be sent to U13 FL12310 in the form of 
ITU-R656 signal format of 8BIT to do line-by-line process.   
 
Send two ways YPRPB signal to U30 MST9883 through selection by N2 PI5V330 in order to do the 
A/D conversion. After this, the signal will be converted into YUV signal of 24BIT, send it to FLI2310 
also. 
 
After a series of procedure such as matrix, chroma and tint etc. by FL12310, the two ways signal will 
be converted into RGB of 24bit, then send it to the main processing chip U12 JAG-ASM. send RGB 
signal it to the main processing chip U12 at the same time. There has another signal which should 
be sent to U12 together with he above two kinds of signal that is: RGB signal of 24BIT produced by 
DV1 through U15 TFP403/501. do the picture format processing for the three kinds of signal in U12. 
Firstly do the A/D conversion for RGB signal of VGA, then do the switching selection together with 
the other two kinds of signal. And then they will be converted into 1024*768 format through digital 
display processing such as OSD and GAMMA correction etc. output it in the form of 24BIT RGB 
signal. Send it to LVDS convertor U31 DS90C383A, then it will be converted into signal format 
which can be accepted by LCD screen namely 3 low-voltage differential signal and 1 clock signal, 
finally send it to LCD screen to do the picture display PWM of U12 can also be used to control the 
brightness of back light-source. 
 
Send SIF (the second IF) outputted by tuner to audio processor N201 MSP3420; send YPRPB and     
audio signal of DVI to N201 through switching selection by U34 HEF4052; Send AV1/SVHS, AV2 
and audio signal of VGA to N201 also. Firstly SIF will be done the switching selection together with 
another four ways of audio signal, finally volume control and sound effect processing will be done. 
Output left-right sound channel signal R/L. one will be sent to SRS sound field processor N203 
M62494 to do SRS processing and finally amplified by N213 and N214 MP7720 to drive the speaker, 
one will be used to drive the headphone through N212 TLE2142 and the last part will be outputted 
as R/L of AV OUT.