Service manual
IMl035
""~,:,,
.,
circuitry
thru
TlOl.
Ql07
is
an
inverting
slave
of
QI06 and
is
driven
alter-
nately
into
saturation
and
cutoff
as
are
all
stages
in
the
horizontal
circuit.
Ql07
output
is
transformer
coupled
to
the
output
stage
with
phasing
of
TlOl
chosen
such
that
Ql08
turns
off
when
Ql07
turns
on.
This
allows
Ql08
to
turn
off
quickly,
thus
minimizing
dissipation.
A
careful
review
will
show
that
Ql08
turns
off
at
a
variable
delay
time
after
receipt
of
the
drive
pulse.
This
action
causes
retrace
to
begin.
During
conduction
of
the
driver
transistor,
energy
is
stored
in
the
coupling
transformer.
The
polarity
at
the
secondary
is
then
phased
to
keep Ql08
cut
off.
As
soon
as
the
primary
current
of
TlOl
is
interrupted
due
to
the
base
signal
driving
Ql07
into
cut
off,
the
secondary
voltage
changes
polarity.
Ql08
now
saturates
due
to
the
forward
base
current
flow.
This
gradually
decreases
at
a
rate
deter-
mined by
the
transformer
inductance
and
circuit
resistance.
However
the
base
current
is
sufficient
to
keep Ql08
in
saturation
until
the
next
polarity
change
of
TlOl.
The
horizontal
output
stage
has
two main
functions:
1)
to
supply
the
deflection
coil
with
the
correct
horizontal
scanning
currents:
2)
to
develop
high
voltage
for
the
CRT
anode and
DC
voltage
for
the
CRT
bias,
focus
and
accelerating
grids
as
well
as
the
DC
voltage
for
the
video
output
stage.
(
Ql08
acts
as
a
switch
which
is
turned
on
or
off
by
the
rectangular
waveform on
the
base.
When
it
is
turned
on,
the
supply
voltage
plus
the
charge
on
C123
causes
deflection
current
to
increase
in
a
linear
manner and moves
the
beam
from
near
the
center
of
the
screen
to
the
right
side.
At
this
time,
the
transistor
is
turned
off
by a
polarity
change
of
TlOl which
causes
the
output
circuit
to
oscillate.
A
high
reactive
voltage
in
the
form
of
a
half
cycle
negative
voltage
pulse
is
developed
by
the
deflection
coil
inductance
and
the
primary
of
T2.
The peak
magnetic
energy
which
was
stored
in
the
deflection
coil
during
scan
time
is
not
transferred
to
Cl22 and
the
deflection
coil
distributed
capacity.
During
this
cycle,
the
beam
is
returned
to
the
center
of
the
screen.
The
charged
capacitances
now
discharge
into
the
deflection
coil
and
induce
a
current
in
a
direction
opposite
to
the
current
of
the
previous
part
of
the
cycle.
The
magnetic
field
thus
created
around
the
coil
moves
the
·scanning
beam
to
the
left
of
the
screen.
After
slightly
less
than
half
a
cycle,
the
decreasing
voltage
across
Cl22
biases
the
damper
diode
CRIll
into
conduction
and
prevents
the
flyback
pulse
from
fur-
ther
oscillation.
The
magnetic
energy
that
was
stored
in
the
deflection
coil
from
the
discharge
of
the
distributed
capacity
is
now
released
to
provide
sweep
for
the
left
half
of
scan
and
to
charge
Cl23
through
the
rectifying
action
of
the
damper
diode.
The
beam
is
now
at
the
center
of
the
screen.
The
cycle
will
repeat
as
soon
as
the
base
of
QI08 becomes
positive
with
respect
to
its
emitter.
e123
serves
to
block
DC
current
from
the
deflection
coil
and
to
provide
"S"
shaping
of
the
current
waveform. "S"
shaping
compensates
for
stretching
at
the
left
and
right
sides
of
the
picture
tube
because
the
curvature
of
the
CRT
face
and
the
deflected
beam
do
not
follow
the
same
arc.
LI03
is
an
adjustable
width
control
placed
in
a
series
with
the
horizontal
de-
4-4