Keithley 7012-S Service Manual

SECTION
3
Maintenance
Display
Test
When
the display
test
is run
all display
segments
and
front
panel indicator lights are
turned
on
for
a
few
sec-
onds.
Perform
the followingsteps to
run the
display
test:
1.
Enable
MENU
and
use the
rotary
knob
to
display
“DISPLAY TEST“.
2.
Press
ENTER
to
run the
test.
Note:
The memory test
can also
be performed
by
sending
J2X over the bus.
AID Test Mode
The
instrument
can
be placed
in the
A/D
test
mode
which allows the
A/D multiplexer
(Ui)
to
be
stopped
in
any one
ofits A/D
phases. This
allows switching
states
to
be
checked
and signal
tracing
to
the A/D input
(see
A/D
Multiplexing
in paragraph
3.8.5).
1.
Tum
off
the Model
236/237.
2.
While
holding
in
the MENU
button,
hirn on
the
Model 236/237.
Continue
to
hold in the
MENU but
ton
until the MENU indicator
hirns
on.
3, Use
the rotary
knob
to
display
“A/D TEST“.
Note
that the
A/D
converter
is stffl
running normally at
this
time.
4,
Press ENTER.
The
following
message
wffl
be
briefly
displayed:
ENTER
TO
EXIT
This
is an
instructional
message
indicating
that
once
in the
A/D test
mode,
pressing
ENTER
will exit the
test mode
allowing
the
A/D converter
to
run nor
mally.
The following
message
will
then
be
dis
played:
A/D
ZERO
TEST
This
message
indicates
that the
A/D converter
is
locked
in
the
zero phase.
5.
The
instrument
can be
placed
in
any of the
other
A/D
phases
(A/D REF,
A/D VOLTS
and
A/D
AMPS)
with
the
use of the
SELECT buttons.
6.
To exit
from the
A/D
test
mode,
press
ENTER.
7,
To return
the instrument
to
the
normal
source/
measure display
state,
press MENU.
Note: The
A/D
test
will
remain
on the MENU
until
power
is
cycled.
3.8.3
Power Supply
Checks
Table
3-3
shows
the various
checks that
can
be
made
to
the power
supplies
of
the
Model
236/237.
In
addition
to
the
normal
voltage checks,
it is a
good
idea
to
check the
various
supplies
with an
oscffloscope
for signs
of noise
or
oscillations.
Table
3-3.
Power Supply
Checks
Step
Item
Component
Required
Condition
Remarks
1
Line voltage
switch
—
Set
to
115V
or 230V
as
re-
Line
voltage
selection,
quired.
2
Line fuse
— Check
for continuity
Remove
fuse to check.
3
Line power
—
Plugged
into
live receptacle;
power on
4 +5V
Digital supply
VR1, pin
2
+5V
±0.25%
Reference
to
digital
common.
5
±15V
Analog
supplies
VR3, pin 3 +15V,
±1V
Reference
to
floating
common.
VR4, pin
3
—15V,
±1V
6
±30V
Analog
supplies
VR5, pin
2
+30V,
±
2V
Reference to
floating
common.
VR6,
pin
3
-30V,
±
2V
7 +5V Analog
supply VR2, pin 3
+5V,
±0,25%
Reference
to floating
common.
8
±150V
Floating
supply
J16, pin 4
+150V,
±
20V
Reference
to
output common.
J16, pin
1 —150V,
±
20V
9
±15V
Floating
supply J8,
pin 1
+15V,
±
1V
Referenced
to output
common.
J8,pin2
÷15V,±1V
10
+50V Isolated
supply
J23,
pin
2 +50V,
±
10V
Referenced
to output common.
3-13

Keithley 7012-S Specifications

General

Brand	Keithley
Model	7012-S
Category	Measuring Instruments
Language	English