Service manual
IMl03S
sawtooth
forming
network.
Linearity
control
of
the
sawtooth
is
accomplished
by
coupling
the
output
at
Ql03
emitter
resistively
back
into
the
junction
of
Cl03 and Cl04.
This
pro-
vides
integration
of
the
sawtooth
and
inserts
a
parabolic
component. The
slope
change
rate
of
the
sawtooth
at
Ql03
output
is
controlled
by
the
setting
of
Al02. The
output
at
Ql03
is
coupled
into
a
resistive
divider
..
Height
control
RllO
varies
the
amplitude
of
the
sawtooth
voltage
applied
to
the
base
of
Ql04 and
controls
the
vertical
raster
size
on
the
CRT.
CIOS
is
used
to
limit
the
amplitude
of
the
flyback
pulse
at
Ql04
collector.
The
vertical
output
stage
Ql04
uses
an
NPN
power
transistor
operating
as
a
class
AB
amplifier.
The
output
is
capacitively
coupled
to
the
yoke. Ll
pro-
vides
a
DC
connection
to
B+
for
Ql04;
it
has
a
high
impedance compared
to
the
yoke
inductance
which
causes
most
of
the
sawtooth
current
of
Ql04
to
appear
in
the
yoke. Rl14
prevents
oscillations
by
providing
damping
across
the
vertical
yoke
coils.
4.3
HORIZONTAL
DEFLECTION
4.3.1
Low
Level
Stages
(Figure
4-1)
The
purpose
of
QlOS
and Ql06
is
basically
to
process
the
incoming
horizontal
drive
signal
into
a form
suitable
to
drive
the
output
stage
Q108.
The
duty
cycle
of
Q108
becomes
essentially
independent
of
the
amplitude
and
pulse
width
of
the
drive
pulse.
This
is
a
necessary
condition
to
assure
stability
and
reliability
in
the
output
stage.
In
adddition,
these
stages
provide
a
horizontal
video
centering
adjustment
by
delaying
retrace
with
respect
to
the
horizontal
drive
pulse.
The
drive
pulse
is
presented
to
Q10S
via
J10l-6.
The
base
circuit
of
QlOS
in-
cludes
a clamp and a
differentiator
which makes
Q10S
output
insensitive
to
drive
pulse
amplitude
and
width
changes.
The
only
requirement
is
that
pulse
amplitude
be
of
2.S
volts
minimum
and
pulse
width
should
be
lO-40~s.
QlOS
together
with
Ql06
functions
as
a monostab1e
multivibrator
with
Ql07
being
a
slave
that
pro-
vides
a
positive
feedback.
Specifically,
when
Q10S
is
turned
on by
the
drive
pulse,
it
discharges
Cl12
at
a
rate
determined
by
the
setting
of
Al03.
When
Cl12
is
discharged
to
2.7S
volts,
Q106
turns
off.
This
change
of
state
turns
Ql07 on and
the
base
drive
to
Ql06 from
R128
is
shunted
thru
Ql07. QI06/Q107
remains
in
this
state
for
nominally
2S~s
until
Cl12
recharges
through
Al03
to
8.2S
volts.
At
this
time,
Q106
is
biased
on
again
by
the
current
through
Al03.
The
mu1tivibrator
is
now
in
a
state
that
Q106
is
on and Q10S/Q107
is
off.
It
will
remain
in
this
state
until
the
next
drive
pulse
occurs
or
power
is
turned
off.
Cl12
is
the
only
timing
capacitor
in
the
circuit
and
has
two
time
constants
associated
with
it.
Primarily,
the
charge
path
between
pin
1 and
pin
3
of
Al03
determines
the
on
time
of
Q107
while
the
discharge
path
through
the
video
center-
ing
control
and
QlOS
determines
the
delay
between
application
of
the
drive
pulse
and
start
of
retrace
(turn
on
of
Ql07).
4.3.2
High
Level
Stages
These
stages
consist
of
Ql07
driving
the
output
stage,
Ql08 and
its
associated
4-2