Circuit Theory Introduction; Chassis Summarize; Base Features; Unit Signal Flow Introduction - TCL SY33 Service Manual

5、Circuit Flow Introduction
1)、Chassis summarize
The main chip of SY33 chassis adopt IC LA76933 of SANYO company ,audio power
amplifier adopts IC LA42352,power supply adopts IC STRW6553, and vertical scan amplifier
adopts IC LA78041.The chassis has low cost and steady function, it has been adopts for
25M63,21M63 model.
2)、Base features
The unit TV supports PAL/DK.I,AV supports PAL/NTSC system, in 2XAV,1x S-video
3)、Unit Signal Flow Introduction
SY33 chassis circuit includes tuner, IF ,SAWF,LA76933 H/V scan circuit ,AV board, side AV
board, keypad board, USB board, power board. audio power amplifier circuit and power supply
circuit etc. The main ICs are LA78041,LA42352,HPC922-C,L7809CV,L7805CV, LA76933,
HCF4052 IC etc.
1）TV signal flow
RF from antenna enters tuner to be processed ( RF being inverted IF), and IF from pin11 of
TU101 passes R106 ,C110 to Q101 IF preamplifier .
After amplifying, IF signal enters pin1 of Z101 to filter and separate SIF and PIF via pin4 and
pin5 of Z101 into pin63 and pin64 of IC201(LA76933) to process PIF .
There are two ways output signal of process IF amplifier:
One is video signal, from pin60 of IC201 , after R227,R228 adjustment ,it is sent pin56 of
IC201 to process demodulation of picture.
Another way is sound signal, from pin5 of IC201 and passes C260 coupling。 The sound
signal is sent to pin1 and pin9 of IC901,after IC901 choosing, signal from pin3 and pin13 of
IC901 is sent to pin2 and pin4 of IC601 to process sound power amplification. After amplifying,
The signals from pin8 and pin12 of IC601 is sent to L/R speaker.
2) AV signal flow
AV1 signal process circuit.
Video signal of AV1from pin1 of P901 enters to pin46 of IC201 to decode process.
Sound signals of AV1from pin2 and pin3 of P901 input is sent to pin5 and pin 14 of IC901 to
choose , after being choosed, the signal flow same as TV sound.
AV2 signal process circuit.