Signal Flow - Daewoo TVZ 1321 Service Manual

SIGNAL FLOW

1. VIDEO & AUDIO
1-1. FROM RF TO COMPOSITE VIDEO
1-1. To select a channel the tuner must receive CLOCK, DATA and ENABLE from the TIMER IC (I701). Then the
tuner(U101) selects a channel frequency by means of PLL circuit operation and outputs a IF signal(Intermediate Fre-
quency).
The signal from the tuner IF output is amplified by Q103, pre-amp. and then passes through the SAW filter. Now the IF
signal is input to pins 8 and 9 of I501, where it is optimized by the VCO and AFT circuits.
The composite video output at pin 51 of I501, contains the 4.5MHZ audio component. However the composite video sig-
nal at pin 45 of I501, does not contain the 4.5MHZ audio signal. Trap Z102 removes the audio signal. Pin 48 of I501,
contains only the 4.5MHZ audio signal which is filtered by Z103.
Pin 1 of switching IC 503 receives it, s signal directly from pin 43 of I501. The signal at this point is selected by an inter-
nal switch in I501. The signal source is either TV video at pin 45 or from pin 42 of I501. There are three video signals,
tuner, external, A/V and PB. video.
Switching IC 503 controls these signals.
1-2. COMPOSITE VIDEO SIGNAL
This CHASSIS includes three video signals. One is from RF(above mentioned), another is from A/V, and the third is from
PLAY MODE.
Switching IC I503 controls these three final video signal.
Once one of the two signals(TV video signal from pin 45 of I501 and A/V video signal from pin 42 of I501) is selected, the
selected signal is from pin 43 of I501 and it is input to pin 1 of I503.
Another video signal from PLAY MODE is input to pin 4 of I503.
Also, One of the two signals(video signal from pin 1 of I503 and video signal from PLAY MODE) is selected, and the
selected signal is transmitted to pin 2 and pin 3 of I503.
Final video signal is input to pin 22 of I701 to detect the CAPTION SIGNAL and it is also input to pin 38(C INPUT), pin
(Y INPUT), pin 44(SYNC INPUT).
And R-Y signal is from pin 23, G-Y signal is from pin 24, B-Y signal is from pin 22, -Y signal is from pin 22, and those
color difference signals are sent to CRT BOARD.
In CRT BOARD, those color difference signals are mixed and amplified by color difference drive method.
1-3. AUDIO SIGNAL
This CHASSIS includes three audio signals. One is from RF(above mentioned), another is from A/V, and the third is
from PLAY MODE.
Switching IC I503 also controls these three audio signals.
TV Audio signal from pin 3 of I501 is input to pin 8 of I503.
A/V audio signal from A/V JACK is input to pin 11 of I503 and outputted to pin 9, pin 10.
So, that audio signal is input to pin 16 of IU01.
Audio signal from PLAY MODE is input to pin 2 of IU01.
One of the two audio signals(audio signal from PLAY MODE, audio signal from A/V mode) is selected and output to pin
22 of IU01 and input to pin 1 of I501.
Audio signal to be input pin 1 of I501 and controlled volume is output to pin 4 of I501.
That audio signal is input to pin 3 of I601(SOUND AMP), and amplified by I601 and output to pin 5 of I601.
Finally the audio signal goes to the SPEAKER.
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