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Meter-mode Sensitivity Alignment
As directed on the screen, connect the shorting bar to the Model 1140A binding posts and press
ENTER to continue. When the alignment step is complete, remove the shorting bar and press any
key to continue.
This completes the VOLTAGE ALIGNMENT.
TERMINAL ALIGNMENT
The TERMINAL ALIGNMENT should be performed after the VOLTAGE ALIGNMENT. Set the
alignment switch (located recessed in a square hole in the bottom cover just to the rear of the
KEYPAD) to the right to enable ALIGNMENT. From the MAIN MENU, select MAINTENANCE,
ALIGNMENT, and then TERMINAL ALIGNMENT. The user should note that if any alignment step is
aborted, any new terminal-alignment data will be lost.
When ENTER is pressed, the technician is prompted to install the shorting bar on the binding
posts. Once this is done press ENTER again.
When prompted on the screen, connect a TYPE T thermocouple (with its error, if any, known in
microvolts) to the binding posts. Immerse the other end in either an ice bath of distilled water or
electronic ice-point set to 0°C. If copper wires are attached to the thermocouple, ensure that the
copper ends are shorted.
Optionally, cover the terminals to shield them from air flow. Enter the offset error, in microvolts,
of the thermocouple at 26°C, if any, and press ENTER.
Once ENTER is pressed, the Model 1140A will commence a countdown of two minutes before
making any necessary corrections. This will be true for all four thermocouple connections: two
on the binding posts and two on the thermocouple connector.
When the previous step is complete, the technician is prompted to reverse the thermocouple
leads at the binding posts and again to key in the offset error of the thermocouple. (If the same
thermocouple is used, this value should already be displayed on the screen with no further
correction needed.)
The above sequence is then repeated using the thermocouple connector in place of the binding
posts. The polarity of the thermocouple connector is the reverse of the binding post: the top
connection is the negative connection, the middle connection is positive, and like the binding
posts, the bottom connection is guard. Insert the bare wire ends all the way into the holes.
Thermocouple Alloy Corrections
This section applies only to units with firmware version 4.40 and above.
Set up the Model 1140A and equipment according to the instructions for binding post readings in
the
Thermocouple Alloy Tests
is found on the binding posts, it may be corrected as follows.
1.
From the MAIN MENU, select MAINTENANCE, ALIGNMENT, and then BINDING POST
CORRECTION.
portion of the calibration procedure. If an out-of-tolerance reading
10-3
Alignment
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