Keithley 237 - SECTION 3 Maintenance; Table 3-10. Display Circuitry Checks

General
Procedure
Perform
the
following
steps
to
change
a
menu
item
pa-
rameter,
perform
a
self
test
or
perform
factory initializa-
tion:
Step 1
:
Press
l'vfENU
to
enter
the
menu
display
state.
Step
2:
Use
the
rotary
knob
to
display
the
desired
menu
item
Step
3:
To
perform
a
self
test
or
factory
initialization
(DIS-
PLAY
TEST, MEM:ORYTEST
or
FACTORY
INTI'
displayed),
proceed
to
step
4.
Otherwise:
1.
To
change
DC
DELAY
or
IEEE
ADDR,
use
the
key-
pad
to
key
in
the
new
value.
2.
To
change
DEFAULT DELAY, SENSE
or
AC
LINE,
use
the
SELECT
buttons
to
display
the
alternate
pa-
rameter.
Step
4:
Press
ENTER.
Step 5:
Repeat
steps
2, 3
and
4
as
needed.
Exception:
MENU
will
disable
if
FACTORY
!NIT
is
per-
formed.
Step
6:
Press
:MENU
to
return
to
the
source-measure
<:Us-
play
state.
General
MENU
Rules
1.
The
MENU
button
toggles
between
the
menu
<:Us-
play
state
and
the
normal
source-measure
display
state.
2.
The
rotary
knob
displays
a
menu
item,
while
theSE-
LECT
buttons
or
keypad
is
used
to
change
the
<:Us-
played
parameter.
3. ENTER
must
be
pressed
to
enter
a
new
parameter.
4.
When
a
parameter
for
DC
DELAY, DEFAULT
DE-
LAY, SENSE,
AC
LINE
or
IEEE
ADDRis
ENTERed,
the
next
menu
item
will
be
displayed.
5. A
keyed-in
parameter
can
be
cancelled
by
pressing
CANCEL
before
ENTER.
6.
The
Source
Measure
Unit
will
return
to
the
source-
measure
display
state
(MENU
disabled)
when
FAC-
TORY
!NIT
is
performed.
SECflON2
Operation
Detailed information
and
a step-by-step
procedure
for
each
menu
item
is
provided
by
the
following
paragraphs.
2.10.1
De
Delay
De
delay
is
used
exclusively
for
de
operation.
De
delay
does
not
affect the
sweep
delay
for
sweep
operation
and
conversely, setting a
sweep
delay
does
not
affect
the
de
delay.
De
delay is
used
to
provide
additional
time
for the
source to settle
if
its
output
level
should
change.
For
a resistive load,
de
delay
is
not
necessary
and
can
be
set to zero seconds. Otherwise,
the
amount
of
delay
needed
is
determined
by
the
RC
time
constant
of
a load.
Five
time
constants (5RC)
provides
99%
settling.
De
delay
can
be
set
from
Osee
to
65sec
with
one
millisec-
ond
resolution.
To
check the
present
de
delay
and
other
menu
item
pa-
rameters,
simply
enable
lv.1ENU
and
use
the
rotary
knob
to
scroll
through
the
menu
items.
If
no
changes
are
to
be
made,
press
:MENU
to
return
to
the
source-measure
dis-
play
state.
To
change
de
delay,
perform
the
following steps:
1.
With
MENU
enabled,
turn
the
rotary
knob
until
the
de
delay is displayed.
For
example,
if
the
delay
is
Osee,
the following
message
will
be
displayed:
OO.OOJ
SEC
DC
DELAY
2.
Using
the
keypad,
key
in
the
desired
delay
period
in
seconds
(OO.OOJ
to
65.000).
3.
Press
ENTER.
The
next
menu
item
will
be
displayed.
4.
If
no
other
menu
actions
are
to
be
taken, disable
:MENU
to
return
to
the
source-measure
display
state.
IEEE-488 Bus
Operation
Over
the
bus,
de
delay,
source
(bias)
value
and
source
range
are
programmed
at
the
same
time
using
the
B com-
mand.
See
paragraph
2.11
for
further
information.
2.1
0.2 Default Delay
Default
delay
is
a
short
delay
(up
to
360msec)
that
is
used
to
allow
for
internal
settling
on
the
low
CUlTent
ranges
2-37