Table of Contents
Advertisement
Alignment
VOLTAGE ALIGNMENT
From the MAIN MENU, select MAINTENANCE, ALIGNMENT, and then VOLTAGE ALIGNMENT. The
user should note that if any alignment step is aborted, any new voltage-alignment data will be
lost, and the instrument will revert to the previous alignment data.
DAC (Digital-to-analog Converter) Bit Alignment
As directed on the screen, connect the shorting bar or cable to the Model 1140A binding posts
and press ENTER. Positive and negative DAC bits will be aligned.
Divider Gain Alignment
When the DAC BIT ALIGNMENT is complete, the Model 1140A will automatically perform the
DIVIDER GAIN ALIGNMENT. When it is completed, the technician is directed to remove the
shorting bar from the binding posts and press any key to continue.
Source-mode Alignment
The dividers discussed in this paragraph are internal and invisible to the user. The 128:1 divider
is active from 0 V to about 0.087 V, the 8:1 divider is active from about 0.087 V to about
1.375 V, and the 1:1 divider is active from 1.375 V to 11 V. As directed on the screen, connect
the Model 1140A binding posts to the null detector using the low-thermal cable and then press
ENTER. The first zero setting is for the 128:1 divider. Using the front-panel controls, set the
Model 1140A binding-post output for 0 µV ± 0.5 µV, then press ENTER. Repeat the process for
the 8:1 divider and the 1:1 divider. For the 8:1 and 1:1 dividers, 0.5 µV may be unattainable.
Simply set it as close to 0 µV as possible. The zero error in the 8:1 and 1:1 dividers is a small
percent of the total error budget for those two ranges. When complete, remove the null-detector
connections from the Model 1140A and press any key to continue.
Meter-mode Zero Alignment
As directed on the screen, connect the shorting bar to the Model 1140A binding posts and press
ENTER. When the operation is complete, remove the shorting bar and press any key to continue.
LSB (Least-significant Bit) Alignment
Ensure there is no connection to the Model 1140A and press ENTER to continue. In approxi-
mately five seconds, the technician will be directed to connect the ten-volt standard to the
Model 1140A binding posts using the low-thermal cable and observing positive polarity. Key in
the actual voltage of the voltage standard to the nearest tenth of a microvolt and again press
ENTER.
When directed, remove the ten-volt connection from the Model 1140A and press ENTER to
continue.
In approximately five seconds, the technician will be directed to connect the ten-volt standard
using reverse polarity. Key in the actual reading of the voltage standard to the nearest tenth of a
microvolt and press ENTER (unless two voltage standards are used, this will be same number but
with negative polarity as that number used above). Again, when this alignment step is completed,
the user is directed to remove all connections to the Model 1140A and to press any key to
continue.
10-2
Advertisement
Table of Contents
