Filter
Top Products
Product:
see
llst
Dale:2-22-88
Chg.
Ref:
M63911
The
standing
cunent
on the horizontal
amplifier Moslets
is
established
by a
resistive
divider
R4046,
R3045,
and
R5038
as
lollows. The
base
of
Q5040
is
set 3.5
volts negative
wilh respect
to the
+300
volt
supply.
The
voltage
drop across
85045
is
then 3
volts
and the
resulting
emitter
currenl
is 2.0ma.
Current
from
the
-15V
source through
resistor R2041
sets the
output
level. Feedback
resistor
R2049
sets
this
outpul
level
at
approximalely
142 volts. Diodes
CR2040,
CR3040,
and
VR4030
provide
transient
voltage
protection
during
turn
on and
under
fault condition.
Capacitor C2031 with
resistor R2035 shape
the
phase
response
of U2030.
Operation
ot the
left
drive
(non-inverting)
section
is
basically
the same
as the
right
drive
(inverting)
section.
Vertical
Section
VIDEO FILTER
OUTfromtheVideo
Processor,
andVERT|CALS|GNALfromlhe
DigilalStorage
are
rouled
through
switch
U60554, under
control of the
STORAGE OFF signal
from lhe
Digital
Storage
board.
Note that
the
video filter
out
signal
is
butfered by U7065 to
prevent
a
change
in
load transients
f
rom aftecting
the signal
level.
A
high
on the STORAGE OFF
line
selects the buffered
VIDEO
FILTER OUT
SIGNAL,
and a
low selects
the
VERTICAL
SIGNAL.
U6065
inverts
the selected
signal
and clamps
it to
ground.
Both
the
VIDEO FILTER
OUTandtheVERTlCAL SlGNALarespecilied
at0.SVtdivwith 0Vforthe
baseline
andpositivevohagesabove
the
baseline.
The
signal
is
re-inverted and olfsel
by bufler U6073 so
cenler
screen
represents
0V.
Buffer U6073
supplies
a
sample
of
this
centered
signallo the
rear-panel
VERT
OUT
connector
via
pins
1 and
2 ol
P7075 and edge
connector
pin
46.
The
output
of u6073 is
also applied through
switch u60558,
when the
R/O
OFF
line
is high,
to
the
vertical
shaper
circuit.
When R/O line is low,
the
VERTICAL R/O
signal
is
applied
to the shaper.
The
Vertical
section
shaper
R4062, R4065,
R4077, R4069,
R4063
and
CR4063,
CR4064,
plus
the
preamplifier
V2062, operates lhe same as the horizontal section.
04078
limits
posilive
excursions
to
approximately
one
division
above the top
of the
crt
screen
to
protect
the
output stages
f rom
being
overdriven.
The vertical
output
stages
are
similar to the horizontal
stages,
with
the
exception
of
high
bias
current.
The
output stage
produces
approximately SmA.
To
correct
for
this
increased
current,
resislors
R31 08 and
R2086
are
lower in value
than
their
counter
parts
R5032
and
R5045
in
the
horizonlal
seclion.
U6024
compares
lhe
signal
levelf rom
the baseline
clamp,
U6065,
wilh
a
relerence
level sei
by divider
R6020
and
R6024. This
produces
the cLlP
signallor the z-Axls interlace
circuit.
when
the
VIDEO
FILTER OUT
signal is more negative
than the reference
level
(approximately
1
division
above baseline),
it
pulls
the
CLIP
line low. R7035
pulls
the
CLIP LINE high if
the signal
is more
positive
than lhe
reference
level.
Variable
resistors
R5020
and
R5030
can
be used to adjust
the
relalive
vertical
position
of the character
readouts andependently
of the
vedical
signal
gain
adjustment
Rl066.
85020
is adjusted
lor
vertical
displacement
characters.
Wilh
the
advance
ol the
reduced
graticule
crt,
R5020 and
R5030
can
be adjusted
to
position
the readout
charaClers outside
ol the
graticule
area.
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