pilot
lamps
R1
30
and
R1
40
on
the
front
panel,
the
signal
outputs
Sthl.la
and
.lb
for
external
lamps
(24
V)
as
well
as
the
two
relays
R3103
and
Rle4
which
provide
floating
signalling
contacts
at
Sthl.5ab
and
.6ab.
The
Operating
mode
is
selected
with
the
pushbuttons
5108
and
8109
on
the
front
panel
or
via
the
inputs
Sthl.2a
and
.2b
which
are
controlled
by
momentary
connection
to
earth.
4.8
Power
Supgly
See
circuit
diagrams
230.8518
S,
sheet
3,
and
230.8918
S.
The
AC
supply
voltage
passes
from
the
rear
connector
STlO
through
the
noise
filter
X10,
the
power
switch
310
and
the
fuse
Sil
to
the
power
transformer.
The
two
secondary
windings
feed
the
control
circuit
YlO.
Lamp
R1
10
indicates
that
the
unit
is
switched
on.
The
board
YlO
is
made
up
of
two
identical
regulator
circuits
for
the
+12
V
and
—12
V
output
voltages.
The
feedback
amplifier
B401
(E&O2)
controls
the
series
transistor
T401
(T402);
resistor
R401
(R402)
limits
the
short-circuit
current
under
fault
conditions.
BAOl
compares
the
reference
voltage
of
G1
404
(+6.2
V,
approx.)
with
that
portion
of
the
+12-V
output
voltage
which
is
tapped
off
at
R406.
The
diode
G1
403
delivers
the
supply
voltage
for
3401.
The
second
feedback
amplifier
B402
iS
fed
With
+12
V
and
—12
V.
R
38122
-
22
