Keithley 486 Instruction Manual page 160

SECTION 7
Maintenance
calibration, ignore the column labeled "lEEE488 Bus
COINIBlld".
Table 7-3. Picoamneter Calibration
263
VIR Amps
Range
222
2oonA
$5
2oopA
2n-A
-I-
263 IEEE-488
Calibration
BUS
current Command
1.PccwonA IA, l.PE-9X
IPJmonA
L3,19E-9X
190.00hA L3,1POE-9X
1.PoooopA L3, lPOE-PX
lP.woo~ I3,19E-6X
190.00&4 J.3,1POE-6X
1.90ooo&4 L&l .9E-3X
Perform the following steps to calibrate the current
ranges of the Model 486/487z
1. Return the Model 486/487 to t&tory default condi-
tions as follows:
A. Press and release MENU until the following
message is displayed:
DEFAULTS
OK
B. Use the rotary knob to display the following
message:
DEFAULTS
FACTORY
C. Press MENU. The instrument will return to fac-
tory default conditions.
2. Connect the Model 263 current source to the Model
W/487 as shown in Figure 7-2. Configure the
Model 263 for V/R AMFS and make sure that
GUARD is disabled. Also, make sure the Model 263
ground link is installed.
3. On the Model 486/487, disable autorange (press
SHIFT and then ALTO RANGE). Make sue the
Model 4861487 is on the 2nA range.
4. Set the Model 263 to the 2nA range and apply
l.POCKlOnA to the Model 486/487.
5. On the Model 486/487, disable zero check to meas-
ure the calibration current source.
6. Press and release MENU until the following me+
sage is displayed:
CALIBRATE NO
7. Use the rotary knob to display the following mes-
SZl&-e:
CALIBRATE YES
8. On the Model 486/487, press MENU. While the in-
strument is performing calibration, the following
message will be displayed:
CALIBBRATE WORKING
9. After the selected range is calibrated, the Model 486
will return to the normal measUTement display state.
The Model 487 will display the next menu item,
which is CAL V SOURCE. For the Model 487, press
MENU to return to the normal measurement display
_ _ _ _
state. state.
10. 10. On the Model 486/487, enable zero check. On the Model 486/487, enable zero check.
11. Set the Model 486/487 to the 2OnA range, set the 11. Set the Model 486/487 to the 2OnA range, set the
Model 263 to source lP.OOOOnA on the 201~4 range, Model 263 to source lP.OOOOnA on the 201~4 range,
and repeat steps 5 through 10.
12. Set the Model 486/487 to the 2OGnA range, set the
Model 263 to source 190.C0OnA on the 2OOnA range,
and repeat steps 5 through 10.
13. Set the Model 486/487 to the 2@ range, set the
Model 263 to source 1.POOoOpA
on
the 2p.A range,
and repeat steps 5 through 10.
14. Set the Model 486/487 to the 20@ range, set the
Model 263 to source lP.OO@$A
on
the 2OpA range,
and repeat steps 5 through 10.
15. Set the Model 486/487 to the ZOO@ range, set the
Model 263 to source lPO.OOOpA on the 2OOpA range,
and repeat steps 5 through 10.
16. Set the Model 486/487 to the 2mA range, set the
Model 263 to source 1.PoOOOmA on the 2mA range,
and repeat steps 5 through 10.
17. Place the Model 263 in standby.
NOTE
For the Model 486, place the CAL LOCK
switchin the "out" position to disable calibra-
tion. Do the same to the Model 487 if you are
not going to calibrate the voltage SOI&.
NOTE
During calibration, the message "CAL ER-
ROR" indicates that the calibration source
value is not within allowable limits. All cali-
bration source values must be 190000 counts
cH9500 counts. In the event of this error, the
calibration will simply not be performed. If
the error persists for cal values that are within
the allowable limits, then servicing will be
necessary.
7-3