TM 11-6625-3025-14/ET426-AA-MMA-010/E154 VII210/T.O. 33A1-8-902-1-1
The trigger obtained at the counter reset is routed to the drive/blanking card for initiation of V blanking at bistable
multivibrator Z6C and Z6D. It is essential that the long blanking pulse be controlled in synchronism with the horizontal
scanning to prevent apparent jitter in the television display. Therefore, a proper selection of pulses is taken from the
earlier stages of the sync count card and routed to the control gate Z4 to time the end of the V blanking pulse developed
by the bistable on the drive/blanking card. Pulse width is controlled by matrix interconnection on the sync count card.
The V drive pulse is developed by the same technique as V blanking. The trigger pulse developed by monostable
Z4 on the drive/blanking card is routed to bistable Z6A and Z6B to start the V drive pulse. Timing pulses selected from the
J-K flip-flop counters control gate Z3 on the sync card. The gate output is routed to gate Z6B to turn the bistable off,
completing the V drive pulse which is then routed out of the card through isolating stage Q3.
The vertical and horizontal blanking pulses are then combined to gate Z5D on the drive/blanking card to provide a
mixed blanking signal. Horizontal and vertical pulses are also routed out of the card as needed to initiate other actions by
jumper selection of output stages Q1 through Q7.
A vertical sync pulse is developed within the vertical blanking interval and is delayed 3H from the start of blanking
and with a duration of 3H. Multivibrators in the sync card produce the front porch delay and the vertical sync width. It is a
further requirement that the vertical sync pulse be absolutely locked to the horizontal scanning rate. Pulses from the sync
count card are then used to control bistable multivibrators which develop the vertical sync timing relationships. Bistable
Z2A and Z2B produces a pulse three lines long (V front porch), Z1A and Z1B produces a six line pulse, and bistable Z3C
and Z3D produces a nine line pulse. Gate Z3A combines the three line and six line pulses to one which extends from the
third to sixth line in the vertical interval for the V sync pulse. Gate Z3B combines the nine line pulse with the V sync pulse
to make two pulses, one from the start of the vertical interval to the third line, and another from the sixth to ninth lines.
This pulse series is used to control the insertion of equalizing pulses before and after V sync.
The equalizing pulses, at 2H rate, are developed by monostable Z5 and triggered by the trailing edge of the front
porch pulse developed by multivibrator Z10. The horizontal sync pulse is developed similarly by monostable Z4 at 2H rate
and counted down to H rate by gate Z8D.
All of these components, i.e. H sync, 2H equalizing pulses and serrations are combined into the sync waveform in
one of three selectable formats:
a. With Equalizing Pulses and Serrations. H sync pulses are transmitted through gate Z7B except from the first
to ninth lines of
4-9
