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U5 Pin 23 and Pin 24 in a balanced way. The other one goes to ASW filter (HS6257) Z2 via C43 and
the video medium frequency signal output also goes to U5 Pin 1 and Pin 2 in a balanced way. In
addition, both Z1 and Z2 have a system switch controlled by U5, with Z1 controlled by U5 Pin22
and Z2 controlled by U5 Pin 3. If PALD/K system is simply required, it can be achieved by earthing
only the control pin of acoustic surface. The audio medium frequency signal is processed at U5 and
is then output from Pin 8, which will come into U8 Pin 80. The video signal is processed at U5 and
output from Pin17 via R55 and V20 and finally R85 (75R) to output the full TV signal which goes to
U8 Pin 54 and Pin 55. The AGC voltage from U5 Pin 14 will control via R87 Pin 1, AGC of the
tuner. IF-AFT signal output from U8 Pin 170 will control U5 Pin 21. The audio carrier differential
frequency signal output from Pin 12 will pass from R66, C44 and V1 and then R88, to output
TV-SIFP signal.
The main fittings in this unit are as follows.
1. Tuner U4
Pin
1
Meaning AGC NC
voltage
2. ASW filters Z1 and Z2 (wherein, HS9453 is for separating the audio frequency and HS6257 for
separating the video frequency), both of which support B/G, D/K, I and M/N.
Pin
Function
Voltage
2
3
4
AS
SCL
Earth
1
2
Medium
Control pin
frequency input
5
6
7
SDA 5VA 5VB
5
5
3
Earth
11
8
9
10
NC
33V
Null
33
4
5
Output
Output
11
IF
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