Trio CS-1575 - HORIZONTAL AMPLIFIER, DISPLAY MODE, AND PHASE DISPLAY CIRCUITS; DUAL-H MODE, BLANKING, CRT POWER, POWER, AND CALIBRATING VOLTAGE CIRCUITS

HORIZONTAL AMPLIFIER CIRCUIT
The
output
of
the
mirror
integration
circuit
Q10
and
Q11
is
fed
to
the
emitter
of
Q14
through
VR4
(WIDTH
ADJUST),
VR104
(POSITION)
and
VR5
(4
POSITION
ADJUST).
Q14
and
O15
are
cascode
connected:
the
collector
of
Q15
is
connected
to
the
collector
of
Q16
which
is
also
cascode
connected
to
Q32
of
the
vertical
axis
to
supply
X
axis
signal
during
X-Y
operation.
These
two
cascode
amplifiers
are
switched
by
IC7
through
D11
and
D12
to
feed
saw-tooth
wave
signal
(SWEEP)
or
X
axis
signal
(X-Y)
to
the
“H”
(horiz-
ontal)
amplifier
Q17-20,
and
the
signal
thus
amplified
is
directly
connected
to
the
horizontal
deflection
plate
of
CRT.
DISPLAY MODE CIRCUIT
The
output
of
the
Schmidt
circuit
B”
is
inverted
by
|C5d
and
is
NAND
connected
through
IC5c
to
the
output
of
the
CHOP
signal
generator
IC5a
and
b
to
produce
UN-BLANKING
signal.
This
signal
passes
through
VR101
(INTENSITY)
and
is
fed
to
the
BLANKING
amplifier
and,
at
the
same
time,
it
is
inverted
by
IC1c
to
produce
clock
signal
to
!C6.
Therefore,
IC6
generates
gate
signal
which
switches
CH1
and
CH2
of
vertical
axis
at
each
sweep
or
each
cycle
of
CHOP
signal.
PHASE DISPLAY CIRCUIT
The
output
of
IC6
is
fed
to
the
“V”
(Vertical)
mode
logic
circuit
and,
at
the
same
time,
it
becomes
clock
signal
to
1C7.
Therefore,
IC7
generates
gate
signal
which
switches
SWEEP,
X-Y
of
horizontal
axis
at
every
two
sweeps
or
every
two
cycles
of
CHOP
signal.
DUAL-H MODE CIRCUIT
When DISPLAY MODE is DUAL-H, Q12 is OFF, so the peak
value of saw-tooth wave from the integration circuit is reduc-
ed to 1/2 of that in the other state. This saw-tooth wave
signal is fed to the input of the horizontal amplifier circuit but
the base input of Q18 of this amplifier is given from Q13.
Q13 is normally OFF and, hence, the base voltage of 018 is
BV. In DUAL-H mode, the emitter of Q13 is earthed through
D22 and the emitter of Q13 is supplied with the output
signal from IC6 and IC7, which is AND coupled through D9
and D10.
Therefore, the emitter of 013 is earthed through D22 only
when IC6 is in CH2 mode and IC7 is in sweep mode and
thus the output signal from IC6 and IC7, which is AND coupl-
ed through D9 and D10, is applied to the base. Accordingly,
Q13 is ON only when IC6 is in CH2 mode and IC7 is in
sweep mode. At this time, the collector voltage is inputted to
the base of Q18 through VR1O05 (DUAL-H CH2 <P
POSITION).
With
these
signals
applied,
the
H
main
amplifier
outputs
two
saw-tooth
wave
signals,
each
having
a
different
DC
com-
ponent,
which
are
synchronized
with
the
output
of
1C6,
thereby
displaying
CH1
signal
on
the
left
half
and
CH2
signal
on
the
right
half
sections
of
CRT.
BLANKING CIRCUIT
The
unblanking
signal
from IC5c
passes
through
VR101
(INTENSITY)
and
is
fed
to
the
unblanking
amplifier
Q45
~
47.
Q45
and
Q46
are
cascode
connected
and
its
output
is
fed
back
to
the
base
of
Q45
through
the
current
regulated
emitter
follower
D47
and
Q47
and,
at
the
same
time,
it
amplitude
modulates
the
output
of
Q48
through
D50
and
D49.
The
output
of
the
amplifier
composed
of
048
and
D48
is
determined
by
the
frequency
of
the
DC-DC
converter.
The
anode
of
D49
is
connected
to
VR23
(INTENSITY
ADJ.)
to
adjust
the
blanking
position
of
INTENSITY.
The
amplitude
modulated
signal
is
DC-restored
by
D51
and
D52,
which
is
applied
to
the
grid
of
CRT
to
produce
a
bright
line
during
sweep
operation.
CRT POWER CIRCUIT
The
CRT
ASTIG
electrode
voltage
from
VR22
(ASTIC)
is
fully
stabilized
through
the
emitter
follower
Q52.
In
the
high
tension
unit
(X68-1210-00),
D2,
Q3,
T1
form
a
DC-DC
converter
circuit;
the
output
from
T1
secondary
is
rectified
by
D3
and
is
connected
to
the
cathode
of
CRT
and,
at
the
same
time,
it
is
fed
back
to
the
regulation
circuit
Q1
and
Q2
while
feeding
FOCUS
electrode
voltage
to
CRT
via
VR102
(FOCUS).
The
output
voltage
is
adjusted
by
VR1
(—1.9
kV
ADJ.).
POWER CIRCUIT
Power
voltage
required
to
drive
the
oscilloscope
circuits
is
stabilized
by
the
tracking
regulator
IC1a
and
b,
IC2a
and
b,
Q41
~
44,
and
is
supplied
through
D44
~
46
and
VR24
(+180V
ADJ.).
CALIBRATING VOLTAGE CIRCUIT
The
oscilloscope
calibrating
voltage
utilizes
0.6
Vp-p
square
wave
obtained
by
switching
Q1
with
power
frequency.