Philips pm3232 - Cathode-Ray Tube Circuitry

71
In
position
X
via
of
TIME/cm
switch
SK2,
the
external
X
deflection
voltage
applied to
the
Ya
channel
is fed
from
transistor TS64
to the
base
of
transistor
TS603,
via
emitter
follower
TS75
and
amplifier TS602.
The
external
X
deflection
voltage
is also
applied to
TB OUT
socket
BUB,
via
emitter
follower
TS516.
The
horizontal
output
amplifier
comprises
two
stages.
The
first
one
with
transistors
TS603
and
TS604
is
provided
with
series-feedback.
The
second
one
consists of
two
single-ended
push-pull
sections
TS607-608
and
TS609-61
1
with
shunt-feed-
back.
From
the
latter
stage
the
deflection
signal
is fed to
the c.r.t.
The
gain
of
the output
amplifier
is
determined
by
the
shunt-feedback
resistors
R628
and
R633,
and the emitter
resistance
of
transistors
TS603
and TS604.
X
MAGN
switch
SKI
allows a
gain
control
in
two
steps.
If
switch
SKI
is closed
(X
MAGN
knob
pulled out),
the
series-feedback
in
the
emitter
circuit
of
transistors
TS603
and TS604
is
decreased
in
such a way
that
the
gain
of
the
output
amplifier is
increased by
a
factor
of
5.
In
the
latter
mode,
the
magnified
mode,
the
gain
can be
preset by
means of
potentiometer
R617 and
in the
normal
mode by
means
of
potentiometer
R618.
In
position
X via
Ya
of
TIME/cm
switch
SK2,
switch
SKI is
bypassed
and the
output
amplifier
works in
the
magnified
mode.
The
horizontal
shift
voltage
comming
from X
POSITION
potentiometer
R1 is
supplied to
the
base
of
transistor
TS604.
Transistor TS606
acts as
a
constant
emitter-current
source
for
amplifier stage
TS603-TS604.
3.1.6.
CATHODE-RAY
TUBE
CIRCUITRY
3. 1.6.1.
General
information
The
c.r.t.
circuitry
provides
control
for
brightness,
focus and
astigmatism,
and
correction
possibilities
for
barrel
and
pin-cushion
distortion
and
the
position
of
the
trace.
The
blanking
circuit
is also
part
of
the
c.r.t
circuitry.
Fig.
3.6.
Cathode-ray
tube
circuitry