Canon A-200 series Service Manual page 97

• Video Output Generator Circuit
U19-3 NON-DISP
Output of CH
U30-3 -----'------'\;--.......
UNDERLINE
U19-11--------:4:-....
Ull-6 --:S-=L_I N_K_ _ _ _ _------'
U16-8 --' C :..=U..c:.RS::;.:O;...:.R:...:.*_ _ _ _ _ _ _ _ _ _---'
U19-7 _R_E_V_ER_S_E_ _ _ _ _ _ _ _ _ _ _ _ _ _ _-----'
The figure above illustrates an overview of this circuit
The character outputs shifted by the shift register (LS166) corresponding to everyone pixel on
the screen, is
~ynchronized
with the OSC clock signal after mixing with the attribute signal.
As above illustration shows, the character output signal is ORed with the UNDERLINE signal.
Namely, when either the character signal or the UNDERLINE signal is HIGH, the pin 6 of U7
becomes HIGH_
Next, the output of 6-pin is ANDed with the NON-DISP signal and the BLINK signal by U28_
In this case, either one of these two signals is LOW, the output terminal of U28 (12-pin) becomes
LOW
Then this output signal is ORed with the CURSOR *signal by U7.
Finally, the output signal from the 3-pin of U7 is compared with the REVERSE signal by U10.
Therefore, when the REVERSE signal is HIGH, the signal from the 3-pin of U7 is inverted at U10.
Conversely, when the REVERSE signal is LOW, that output signal from U7 will be output from
U10 as its logical level is unchanged.
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