SERVICE MANUAL FOR M35&36; CHASSIS

TCL
Chassis M35&36 Service Manual
SAWZ101 and Z101A, the IF signal is inputted into IC101 from Pin4-5 (VIF input) and Pin7 (SIF input). The
VIF signal pass the video amplifier and video detector and is changed to CVBS. And IC101 sends out
CVBS from Pin18 of itself. Having passed Q104 and Q105 and the trapper network consisted by L102,
Z104 and Z105, CVBS is divide into two way. One enter IC201 from Pin19. And another pass Q903 and
arrive the video output terminal of TV.
IC101 sends out QIF signal from Pin13 of itself. QIF signal enters the sound process circuit which is mainly
consisted by IC1001. A 38.9MHz VCO coil is connected with Pin 15 and 16 of IC101. By adjusting the
magnetic core of T101, the AFT curve can match the standard. IF AGC delay signal comes out from Pin1
of IC101, and goes to tuner for high frequency signal amplifying with auto-gain control.
3. Sound process section
M35/36 chassis adopts MSP3415G made by Micronas also as sound process IC. This IC can process the
stereo signal and NICAM signal.
The QIF signal pass a high pass filter network consisted by C1024, C1024A and L1102, and enter IC1001
from Pin47. This QIF signal is changed to sound signal via amplitude-limit amplifier and frequency
discrimination circuit and sound deemphasis circuit inside the sound process IC. On the other hand, the
two way audio signals from audio input terminal enter IC1001 from Pin42/44 and Pin39/40, they and the
TV sound signal will be switched by IC1001. IC1001 selects one way sound signal from these three ways
and divide it into two ways: One way is from Pin 24/25 to the audio amplifier circuit which is mainly
consisted by TDA7057AQ and to drive the speakers. Another way is from Pin30/31 to audio out terminal of
TV. VCT3831A sends out the volume control signal via Pin64 to control the speakers volume.
4. Video signal process section
The video signal from sound IF filter circuit enter IC201 via Pin19, and pass a video amplifier inside of IC.
Then the video signal is splitted into two ways, one way to the sync-separation circuit, another one to the
clamp circuit, black strength circuit, luminance delay line, sharpness improvement circuit. Then this signal
is done with matrix operation with the C signal, which is from the chroma process unit, in the matrix circuit.
The finally result is IC201 output R/G/B signal to CRT board from Pin42/43/44 and to drive the CRT.
Another video signal which come from video input terminal of TV, is switched by electrical switch inside
IC201 and out from pin11 of IC201 as the video output signal to video output terminal.
5. Chroma process section
The chroma signal is separated from the video signal, which is from pin19 or pin20 or 21 (video input or TV
video signal), after having passed a band/ high pass filter. Then the chroma signal is amplified by ACC
circuit and splitted into two ways. One way goes to the demodulation unit and another way goes to the
APC circuit to make the chroma subcarrier oscillator to generate reference subcarrier signal which is
needed for sync demodulation, and to sent it to the demodulation unit. The R-Y and B-Y signal
demodulated from chroma signal are sent to color system recognition circuit. Having passed the system
recognition switch circuit, it goes to 1H delay line and other control circuit. Finally it goes to matrix circuit.
The Y signal from luminance process unit will be done with matrix operation with R-Y and B-Y signal via
matrix circuit. If the color system is NTSC, the TINT circuit is enabled. This TINT circuit is a phase shift
circuit. It can change the phase of the reference subcarrier which is sent to APC circuit and to shift the
APC output voltage, therefore , to change the oscillator frequency (phase) of chroma VCO. So the chroma
will be changeable.
5 03.Mar.2003