Sony PVM-9L2 Service Manual page 38

Section 5
Theory
of
Operation
5-1
.
D
Board
and P Board
Power
Supply Block
When
13
V
is
supplied
to the
D
board
CN1505
from
the
G
board, 13
V
is
supplied
to
the
DC-DC
convert-
ers for
40
V, 12 V, 6
V
and
-6
V
respectively through the relay
(RY1501).
The
DC-DC
converter generating
40
V
consists
of IC505, Q508, Q509,
QSIO and D505. The
generated
40
V
is
supplied
to
FBT
as the
power
supply for deflection system.
The
DC-DC
converter generating
12
V
consists
of IC505,
Q1501, Q1502, Q1503, Q1504, Q1505,
D1502
and D1503. The
generated 12
V
is
supplied
to
the
B
board
as
its
power.
The
DC-DC
converter generating
6
V
consists
ofIC1501,Q1506,Ql
508,
Q
1 509,
Q
1
5
1
2,
and
D
1
506.
The
DC-DC
converter generating
-6
V
consists of
IC
1501,
Q1507, Q1510, Q1511, Q1513, and D1507.
The
generated 6
V
and -6
V
are supplied
to
the
option boards as
its
power.
The power
regulator for
5
V
is
the 3-terminal
power
regulator consisting of
IC1503 and
IC1504.
The
5
V
power
is
generated
from
the
above
regulated
6
V
and
supplied to the
B
board
as
its
power.
When
the unit
is
operated
on
DC
power,
the
DC
power
is
supplied
from
lithium battery via
CN1502
or
external
DC
power through
CN1503.
When
the
power
switch
is
turned on, the relay
is
switched to the
DC
position so that the
power
is
supplied
to
the respective
DC-DC
converters.
If the 13
V
power
is
supplied
from
the
G
board
at
the
same
time,
it
activates
the
AC
prioritize circuit
Q1514
so
that
the
DC
power
supply
is
stopped and
the
DC
power
supply
is
also stopped.
Therefore,
be
sure
to
disconnect the
AC
power
cord
from
AC
power
source.
When
the battery
voltage decreases
lower
than
DC
9.5
V,
the unit
is
shut
down
by IC1506
in
order
to
protect battery.
When
the battery voltage increases higher than
DC
21V,
the
OVP
is
activated
by IC1506-
Deflectlon
Block
Deflection drive pulse
is
generated
by IC502
as
it
is
synchronized with the
H.
SYNC
at
CN501 pm-4
and
V.
SYNC
at
pin- 12.
The
horizontal deflection drive pulse
is
supplied to
Q802
and
Q803 on
the
P
board
via
CN502
pin-4 to
drive the horizontal deflection system.
At
the
same
time,
the distortion correction
waveforms
including
DC
component
are
supplied
to
Q513
via
IC501 from IC502
pin-9 in
order
to
correct the H.
SIZE PIN
distortion via
bus
control.
The
vertical
deflection
is
performed by
the
sawtooth
wave
that
is
output
from IC502
pin-8
and
is
supplied
via
IC504
to
IC506.
V
SIZE
and
V.LIN
are adjusted
by
the
IC 502
bus
control.
High Tension Block
The
H.
OUT
pulse that
is
generated
by Q803 on
the
P
board,
is
boosted
by
FBT
to
about 16
kV
and
supplied
to
CRT.
Audio Biock
The
audio signal
is
input
from
CN1507
pin-2 of the
D
board.
It is
amplified
by IC1507 and
supplied to
speaker
via
AUDIO
OUT.
Degauss Block
Because
this
unit
can be
operated
on
battery,
the
DC
degauss
circuit
is
incorporated.
When
the
power
switch
is
turned on,
and
also
when
the
DEGAUSS
switch
on
the front
panel
is
pressed,
the degauss drive signal
is
supplied to
CN1507
pin-5
from
microprocessor.
IC1510 and IC151
1
are
oscillated as triggered
by
the
degauss drive
signal.
The
voltage that
is
charged
by
the time constant of
R1818
and
C1589
generates the
damped
vibration signal
and
the
degaussing
is
performed.
PVM-9L2
5-1