Service Information
5-6
14. The Model 2001 will then display the precise calibra-
tion voltage:
Cal: 200.00000 mVDC
15. Make sure that the divider ratio is still set to 10
4
. If
you are using the recommended 200mV calibration
voltage setting, simply press ENTER at this point.
Otherwise, set the displayed value to the exact cali-
bration voltage, then press ENTER. (Note: 200mV is
recommended for most accurate results.)
16. Next, the unit will prompt you to set the divider ratio
to 10
3
as follows:
Set 262 to 10^3
Set the Model 262 divider ratio to 10
3
, then press
ENTER.
17. You will then be prompted to set the divider ratio to
10
2
:
Set 262 to 10^2.
Set the divider ratio to 10
2
, then press ENTER.
18. Next the instrument will prompt you for the calibra-
tion date:
CAL DATE: 01/01/93
Change the date as required, then press ENTER.
19. The multimeter will then prompt for the calibration
due date:
NEXT CAL: 01/01/94
Change the calibration due date as required, then
press ENTER.
20. Finally, the unit will indicate that preamplifier cali-
bration is completed:
PREAMP Cal complete
21. Press ENTER to complete calibration and save new
calibration constants. If you wish to abort the process
without saving calibration constants, press EXIT
instead.
22. Press EXIT to return to normal display.
NOTE
If an error occurs, an appropriate error
message will be displayed. See the dis-
cussion below on error messages.
IEEE-488 bus calibration procedure
Follow the steps below to calibrate the Model 1801 over
the IEEE bus. Table 5-2 lists IEEE-488 bus calibration
commands, and Table 5-3 summarizes the bus calibration
procedure. (See Appendix B for calibration program list-
ings.) Note that commands must be sent in the order indi-
cated in Table 5-3. To abort the calibration procedure,
send :CAL:UNPR:PRE:ABOR.
Procedure
1. Make sure the Model 1801 is properly installed, as
explained in Sections 2 and 3 of this manual.
NOTE
The offset adjustments explained in
paragraph 5.2.5 must be performed
before calibrating the Model 1801.
2. Connect the Model 1801, DC calibrator, and low-
thermal voltage divider, as shown in Figure 5-3. Be
sure that the preamplifier module is installed in the
thermal isolation enclosure, and that the lid is firmly
in place.
3. Connect the Model 2001 IEEE-488 bus of the con-
troller you intend to use to send calibration com-
mands to the instrument. Use a shielded IEEE-488
connecting cable to minimize noise.
4. Turn on the Model 2001 and the calibrator, and allow
a two-hour warm-up period before continuing with
calibration.