Filter
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Theory of Operation
6–2
760A / 760D / 760N
45° Matrix. The Left and Right signals are added in U179 and subtracted in
U379 to produce L+R and L–R signals. These signals, if applied to the CRT,
will rotate the pattern 45° counterclockwise, so that the Left signals are indicated
along the left 45° diagonal and Right signals along the right 45° diagonal. A
vertical line indicates Left and Right signals are equal and in phase (mono). This
orientation makes pattern interpretation more natural. The user may bypass the
matrix using jumpers J273 and J373 so that Left signals are indicated on the
vertical axis and Right signals on the horizontal. Equal Left and Right signals
(Mono) are then indicated along the right 45° diagonal.
L+R
–L
R–L –R
LEFT
Input
Amplifier
RIGHT
Input
Amplifier
AUX
Input
Amplifier
45°
Matrix
Orthogonality
Correction
Gain
Control
Logic
Gain
Control
Gain
Control
Low Pass
Filter
Low Pass
Filter
Z–Axis
Dimming
Horizontal
Deflection
Amplifier
Vertical
Deflection
Amplifier
Z–Axis
Amplifier
CRT
LEFT
LED
BAR
10
X
10
LEFT
Bar Cathode
Driver
RIGHT
LED
BAR
10
X
10
AUX
LED
BAR
10
X
10
RIGHT
Bar Cathode
Driver
AUX
Bar Cathode
Driver
LEFT
Bar Anode
Driver
RIGHT
Bar Anode
Driver
AUX
Bar Anode
Driver
LEFT
Peak
Processor
RIGHT
Peak
Processor
AUX
Peak
Processor
LEFT
Dynamic
Response
RIGHT
Dynamic
Response
AUX
Dynamic
Response
Master
Clock
Down
Counter
DAC
Scale
Shaper
PEAK
HOLD
Select Logic
SELECT
EXPAND
SCALE
DISPLAY
GAIN
SUM
DIFF
Circles represent Front–Panel Controls
.
.
.
.
H.
POS.
V.
POS.
INTEN–
SITY
Figure 6–1: 760A / 760D / 760N Block Diagram
CRT Orthogonality Correction. A small amount of the signal from the horizontal
signal path (amplitude and polarity adjusted by R463) is applied to the vertical
path to correct for small differences in CRT deflection orthogonality.
MATRIX & AGC CONTROL
LOGIC <4>