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3330B
the
flip-flop will
be
in
the
wrong
state
due
to the
Logic
"0" from
A3A2S2.
A
Logic
"0" must
be present
at
the
output of
the
flip-flop
(pin ICl
14)
when
the operate-
mode
is
selected;
otherwise
it
is
impossible
to energize
the
instrument
output's.
If a
Logic
"1"
(zero
volts)
is
present
at
pin
14
when
the operate
mode
is
selected,
Q15
and
Q16
will
turn on, holding
the
operate
line
down
to nearly
zero
volts.
The
instrument
must
then be placed
in
the
standby
mode
to
set
the
flip-flop
before the operate
mode
can
be
selected.
3-119.
The
indicator
lamps
provide
visual
indications
of the instruments
status
while
in
local
mode. The lamps
and
their
function
are:
DSl
DS2
DS3
DS4
DS5
I
LIMIT/V TRIP
indicates limit or
trip
mode
DS6
OUTPUT
>
1
0Ov
DS7
CONSTANT CURRENT
DS8
CONSTANT VOLTAGE
DS9
OPR
operate
mode
DSIO
REM
remote
mode
3-120.
DECADE
SWITCU
ASSEMBLY
(A3A1).
This
assembly
contains
tire
seven
decade
switches used
to select
the desired
output
current or voltage while
in
local
mode.
Each
switch
is
an eleven
position switch; the highest order,
SI, has
positions
ranging
from
0
to 10,
while
the
remaining
switches
S2 through S7
have
a
range
of 0
to X.
The
"X"
indicates
a
'Narry
one"
function, so
that an
output
voltage'
of,
for
example,
1100,0000
volts
would
be
dialed
as
10X0.0000.
3-121.
On
the
schematic diagram
tlie
switches
are
shown
for representation
as
5
position
switches, the positions
being
8,
4, 2,
1,
and
0 with
numbers
in
parenthesis
by
the
positions.
The
8-4-2-1
corresponds
to the
BCD
coding
applied
to
the ladders.
On
S2
position
1
,
for
example,
the
numbers
1,
3,
5, 7,
9,
in
parenthesis indicate that
CR5
is
connected
to the
wiper
arm
in
the
decade
settings
1,
3, 5,
7,
and
9.
3-122.
The
wiper
arm
of each switch
is
connected
to
—5
volts.
The
four
outputs of
each
switch
are
connected
to the appropriate
relay driver in
the ladder
drive
assembly-
3-123.
SWITCH
BOARD
(A3A2)
This
assembly
con-
tains the
front panel
push button
switches
used
to activate
the various conditions
in
the
instrument.
The
groups of
Provide decimal point
indication
in
associa-
tion
with
the
front
panel
Decade
Dials.
TO OPERATE
A3A2S2
(STDBY)
5V INPUT
(CR
(CR
25V INPUT
CONDITION
NOR
FUNCTION
DEFINED
INPUTS
Where:
1
•
Zero
Volts
0
3.6
to
-20
Volts
(In this
application),
GATE OUT
Initially
25V
not yet
on
PROGRAMMING
SUPPLY
COMMON
Standby
Switet^
t
Initially in
••
25V
not yet
on
q_
Operate
--25V
now
on
.|
INHIBIT
CIRCUIT
TRUTH
TABLE
Figure3-8.
INHIBIT
CIRCUIT
3-15
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