INSTRUCTION
MANUAL
-
MODEL
DLP
400-5-750A
18
5.0
THEORY
OF
OPERATION
5.1
INPUT
CIRCUITS
A
schematic diagram is
provided
in
back.
AC
power
is
applied
through
the
line
cord,
through
fuse
F101,
and
AC
ON/OFF
switch
S115
to
the
AC
indicator
lamp,
blowers
B101
and
B102,
and
the
primary
of
T1
and
T101.
The
secondary
of
T1
is
rectified
and
filtered
in
both
the
positive and
negative
directions
compared
to
the
center
tap,
generating
approximately
+25V
and
-25V
on
capacitors
Cl
and
C2,
respectively.
The
negative
voltage
is regulated
to
5.6V by
constant current
source
Q5
and
associated
components
R12,
VR7
,
R13,
Rll, and zener diode
VR6.
The
+25V
is
regulated
to
+16V
by
constant
current
source
QI, and
its
associated
components
Rl,
VR5,
R3
,
R2
,
and
zener
diodes
VR2
and
VR3
,
which
generate
+16V and
+8V.
Secondary
6-7
of
T101
is
half-wave
rectified
in
the
positive
and
negative
direction
by
diodes
A2-CR3
and
A2-CR4,
developing
approximately
200VDC
across
filter
capacitor
A2-C2
and A2-C3,
which are
series connected
to privide
approximately
400VDC.
Secondary
8,
9,
10
of
T101
is
rectified
in
a
full
wave
center
tap
configuration
by
diodes
A2-CR1,
A2-CR2
and filtered
by
capacitor
A2-C1,
providing
approximately
25VD
A
bias
supply which tracks the DC input
voltage
with a
potential
of
approximately
5V
less
is
developed
by
zener
diode
A2-CR7,
A2-Q1,
Q101,
and
their
associated
components
on
circuit
board
A2
.
[OJ400-5-75QA]
