6. PAL Low-pass Filter
The R-Y signal that is output from IC2804 pin-23 passes through the active low-pass filter (Q3809,
Q3810) and is input to IC3802 pin-16. IC3802 contains the built-in 1H delay circuit using a line memory.
The output signal after 1H delay is added to the non-delayed signal at pin-11 and is output. The R-Y
signal from pin-11 is output via the switch circuit (IC3804, IC3806) and the level adjustment circuit
(IC3807). The B-Y signal takes the equivalent circuit.
7. KILLER Detection Circuit
When the NTSC/PAL signal is input, Q4802 turns on. When the input signal is black-and-white signal,
voltage at pin-25 (KILLER FILTER) of IC2804 increases. This voltage is compared with the reference
signal at IC3801 (1/2) that generates the KILLER signal.
When the SECAM signal is input, Q4802 turns off. Voltage at pin-18 (SECAM) of IC4801 goes HIGH
that becomes the KILLER signal.
8. Control Circuit
System of this unit is controlled by IC1101 (system control CPU) on the M board. Various setups are
stored in IC4804 (EEPROM). The adjustment data of IC4804 is read and D/A converted to output the
adjustment voltage from the D/A converter (IC2805, IC4803).
5-3. C Board
OO L5 series
IC701 is the R signal drive IC. Q704 is the auto cut-off circuit. The output pulse flows through R755
when Q704 turns on. The reference pulse that is converted from current to voltage by R755, enters
IC2001 pin-25 via Q2003 on the B board where it drives the auto cut-off circuit. Amplification factor of
the signal is determined by R720 and R724, and is 29 dB. The above circuit operations apply to the G and
B signals in the same way.