Service manual
IM1035
flection
coils.
The
variable
inductance
allows
a
greater
or
lesser
amount
of
de-
flection
current
to
flow
through
the
horizontal
yoke and
varies
the
width
of
the
horizontal
scan.
Linearity
control
is
provided
by
modifying
the
deflection
coil
voltage.
During
retrace,
an
auxi11iary
winding on
the
f1yback
transformer
supplies
a
pulse
which
charges
Cl19
through
rectifier
diode
CRl12 and L102.
This
voltage
is
then
applied
in
series
with
the
deflection
coil
when
the
damper
diode
turns
on
at
the
start
of
trace.
The
voltage
is
sawtooth
shaped
and
has
the
effect
of
decreasing
the
deflection
coil
current
as
a
function
of
the
sawtooth
shape.
This
compensates
for
the
stretch
normally
found on
the
left
side
of
the
screen
due
to
the
deflec-
tion
coil
and
system
RL
time
constant.
Linearity
is
optimized
by
adjustment
of
L102
which
acts
as
an impedance
to
the
pulse
from T2.
The
negative
f1yback
pulse
developed
during
horizontal
retrace
time
is
rectified
by
CR110
and
filtered
by C117.
This
produces
approximately
-130
VDC
which
is
coupled
through
the
brightness
control
Rl17
to
G1
of
the
CRT.
This
same
pulse
is
transformer-coupled
to
the
secondary
of
T2
where
it
is
rectified
by
CR2,
CRl13 and
CR114
to
produce
rectified
voltage
of
approximately
l2KV,
400V
and
32V
respectively.
l2KV
is
the
anode
voltage
for
the
CRT,
while
32V
is
used
for
the
video
output
stage,
and
the
400V
source
is
used
for
G2
and
G4
voltages
for
the
CRT.
4.4
LOW
VOLTAGE
SUPPLY
The
TV
90/120
models
are
available
with
an
internal
power
supply.
This
supply
utilizes
an
integrated
circuit
voltage
regulator
which
supplies
15VDC±2.5%
to
J103-1.
It
also
supplies
12.6
VAC
to
J103-3
and 4
for
the
CRT
filament.
The
l20VAC
primary
voltage
(220/240V
optional)
is
stepped
down
at
the
secondary
of
T1
where
it
is
rectified
by
CRI
and
filtered
by
CI.
A2
functions
as
a
series
regulator
to
drop
the
rectified
voltage
down
to
l5V
at
pin
2.
The
regulator
maintains
a
constant
output
voltage
(within
2.5%)
with
changes
in
line
voltage
load.or
temperature.
It
is
capable
of
supplying
1.5
amps
and
features
internal
current
limiting,
thermal
shutdown and
safe
over-voltage
protection.
A
hermetically
sealed
TO-3
case
is
used
for
high
reliability
and low
thermal
re-
sistance.
If
a
short
circuit
is
present
at
the
output,
the
current
limiting
feature
of
A2
will
cause
the
output
current
to
fold
back
to
safe
levels.
The
fast
limiting
action
of
A2
is
very
effective
in
protecting
transistors
from abnormal
loads.
The
resistor
Rl,
is
used
to
reduce
the
power
dissipation
in
A2.
4-5