Model
6960
A
Section
III
Prior
to
turn on
set
the
VOLTAGE ADJUST
control
on
the
master
unit
fully
counterclockwise
and
the
ones
on
all
slave
units
fully
clockwise.
Then turn on
all
units
and
adjust
the
master
unit
to
the
desired
voltage.
If
the
slave
units
do
not
track
the
master
unit,
turn
off
all
instruments
and
recheck
your
connec-
tions.
For minimum
ripple
across
connected
outputs,
add
a 5
/uF
(or
larger)
/50
V
electrolytic
capacitor
from
+S
to A2
terminals
on
all
slave
units.
All
instru-
ments must be
operated
on
the
same
range.
Dl
not
connect
more
than
ten
units in
series
to
avoid
exceeding
the
400V
rating
from
+or
-
output
terminals
to chass
is.
3-]
1 Remote Programming
3-12
3-13
The
output
voltage
of
Model
6960A
may
be
changed
by
actuating
the
front
panel
VOLTAGE ADJUST
con,rol
or
by chong"'::;
,ll"C
'''''0''
or
the externa'i
programming
resistor.
If
a number
of
Model
6960A's
are
connected
in
series
or
parallel,
all
units
can
be
conrrolled
by
cho'lgi"9
rt;e
programming
resistor
attached
to the master
unit
only.
Thus
the
output
voltage
may
be
program-
med
remotely
by using
stepping
switches
to
change
the
value
of
the
external
resistor
in
accordance
with a programmed
procedure.
The
connections
on the
rear
terminal
strip,
shown
in
Fig.
3-2
e
have
only
to
be performed on the master
unit.
Then the
output
voltage
will
vary
lire~·I,:
with
the
programming
resistor
at
a
rate
of
approximately
200
O/V,
that
means,
a
2000
resistor wi
II
give
1 V
output,
0400
0 resistor 2V
output,
etc.
When using a
switch
to
change
the programming
resistance
whi Ie
the
instru-
ment
is
on,
be
sure to use a
shorting
contact
type
switch
to
keep
the
voltage
of
the
supply from rising
while
switching.
If
the
programming
circuit
is
opened,
even
momentarily,
the
voltage
from
the
supply will
rise.
This
switching
tran-
sient
may
damage
the
circuit
under
test.
Remote Sensing
When
the
rear
terminals
of
the
instrument
are
connected
in
the
normal
fashion,
the
voltage
for
regulation
control
(sensing
voltage)
is
taken
from
the
output
of
the
supply
at
the
front
panel.
This
is
not
always
the
best
point
to
obtain
this
voltage,
because
there
may be a
voltage
drop
in
the
supply
leads
between
the
load
and
the
supply.
To
get
around
this
effect,
a
separate
set
of
terminals
for
the
sensing
voltage
(+S
and
-S)
are
provided
on
the
rear
of
the
instrument.
These
terminals
permit
a
separate
pair
of
leads
to
connect
at
the load
to
supply
the
sensing
voltage.
The leads
carry
no load
current
but
are
inside
the
regulation
loop
of
the
ampl
ifier.
To
use
remote
sensing,
run a
separate
set
of
leads from
the
load to
the
sensing
terminals.
These
leads
do
not
need
to be as
heavy
as
the
supply
leads
but
they
must be
protected
against
hum
pickup.
Run
either
twisted
pair
open
wire
leads
3-4
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