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3.3.3
Sync Processor
Monostable multivibrator, IC103B and NANO gate, IC104C
forms a kind of differentiator to separate the horizontal
sync.
NANO gate IC1040 inverts the horizontal sync signal to
supply positive sync to the differentiator formed by
Cl69 and Rl85.
Ql41 is biased in the OFF state.
Negative edges of the positive sync signal (which 'are
the trailing edges of the horizontal sync pulses) drive
Ql41 to the ON state.
The output across Rl86 is a
positive pulse during the backporch interval.
This pulse drives the backporch gate FETs, Q207, Q237
and Q267.
The vertical sync pulse is separated by monostable multi-
vibrators, IC106A and IC106B.
Monostable multibibrator, IC103A generates the negative
going vertical sync pulse.
External vertical sync (VD), if used, is converted to
TTL level by IC101A and coupled through EXCLUSIVE-OR
IClOSD to monostable multivibrator IC103A.
This PCB unit contains video amplifier, backporch clamp
circuit, ABL circuit and Blanking circuit.
3.4.1
Video-Driver Amplifier
R.G.B. video-driver amplifiers have quite same _circuit
and components.
The Green video signal from the PCB-
VIDEO-SUB enters emitter-follower at the base of Q201.
3-6
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