Keithley 236 Service Manual

SECTION 2
Calibration
29.
On the
Model
193A,
select
the Ohms
function, 2002
range and
disable
ZERO.
30.
Repeat
step
3
to zero
the
Model 193A.
31. Measure
and
record the
value of the
100Q resistor.
32. Set
the Model 193A to DCV, the
2V
range, and dis
able
ZERO.
33,
To cancel
any
offset,
zero the
Model
193A
by
short
ing its
input(VOLTS
HI
to
LO),
and enabling ZERO.
34,
Remove the short from the input
of
the Model 193A
and
set the Model
263 to
source 9.0000mA on the
2OmA
range and enable
OPERATE.
35, Record the
voltage measurement from the Model
193A and
caiculate the current.
I9mA
15 the
characterized current
for the 9mA range of
the Model
263. lt is
used to calibrate
the lOmA range
of the
Model
236/237.
Using a pendil, record the ca1
culated
value
of
IA
in Entry
5
of Table
23.
36.
Place
the Model
263
in standby.
37,
In the
test fixture, remove the 1002 resistor and in
stall the 1O2
resistor
(R-18540).
38.
On the
Model 193A DMM, disable ZERO and select
the 200mVDC range.
39, While
in
standby,
set
the
Mode1263 to +9.0000mA on
the 2OmA
range.
40,
Zero the Model
193A
by
shorting its input (VOLTS
HI to
LO)
and
enabling ZERO.
41.
Remove the short
from the input of the Model 193A
and place
the
Model 263 in operate.
42, Record
the
voltage measurement from the Model
193A and
then place
the Model 263
in standby.
vb0 =
_________________
mV
43,
Caiculate the
actual resistance of the 1O2 resistor
as
follows:
where;
I is
obtained from Table 23.
NOTE
To
store
calibration constants in nonvolatile
memory,
place
the CAL LOCK switch to
the
unlocked “in“
position
(see
paragraph
2.5).
With the switch
in the locked “out“ position,
calibration will
be
temporary. That
is,
the
new
calibration constants
will
be
lost when the in
strument is turned
off,
2.6.2 Voltage Calibration
WARNING
The following procedure uses
hazardous
voltages
(1000V
forthe Model
237)
that could
cause
injury
or
death, Exercise extreme cau
tion when encountering
these
lethal voltage
levels,
Make
sure
to
connect the Model
8006
Interlock Circuit
to
the Model 236/237
clx
! Calibrate
common mode
Riooo =
Rioo
iS used
to
calibrate the lOOniA
range
of the
Model
236/237.
vb00 =
_________________
v
vb00
=
Riooo
mA
For voltage calibration, connect the Model 193A DMM to
the
Model
236/237
via the Model
8006
test fixture as
shown in Figure
23.
Jumper A is initially installed to
short the
output of
the Model
236/237
and the input of
the Model 193A,
Perform the following steps to calibrate the voltage
source and measure
ranges:
1.
Set
the Model 193A DMM
to
D
volts and
autorange.
2. With the short
(Jumper
A)
installed, zero the Model
193A
by
enabling ZERO.
3,
Place the Model 236/237
in
operate.
The calibration
mode cannot
be
entered
with the Model 236/237
in
standby.
4,
Over the 1EEE488
bus, send the following command
to enter the calibration
mode:
cox
! Enter calibration mode
Note: All other
calibration commands
(Cl
through
C59)
will be
ignored unless the
CO
command is first
sent over the bus.
5,
With the short still installed,
send the following
com
mand over the bus to
perform common
mode
cali
bration:
Vb 00
RboQ
I9mA
24

Keithley 236 Specifications

General

Brand	Keithley
Model	236
Category	Measuring Instruments
Language	English