Keithley 2750, Service Manual

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2-24 Calibration Model 2750 Multimeter/Switch System Service Manual
Extender board connections
The Model 7700 being calibrated should be connected to the 7797 Calibration/Extender
Board, and the extender board should then be installed in scanner Slot #1. Note that the
module being calibrated will be external to the Model 2750 to avoid card heating during
calibration.
Model 7700 calibration
NOTE Before calibrating the Model 7700, make sure that power has been removed
from the card for at least two hours to allow card circuitry to cool down. After
turning on the power during the calibration procedure, complete the procedure
as quickly as possible to minimize card heating that could affect calibration
accuracy. Allow the Model 2750 to warm up for at least two hours.
Front panel Model 7700 calibration
1. Connect the Model 7700 to the Model 7797 Calibration/Extender Board (see
“
Extender board connections ”).
2. With the power off, install the Model 7700/7797 combination in Slot 1, and select
the rear inputs with the INPUTS switch. Allow three minutes for thermal
equilibrium.
3. Accurately measure and record the cold temperature of the Model 7700 card sur-
face at the center of the card with an RTD sensor.
4. Press in and hold the Model 2750 OPEN key while turning on the power.
5. Press SHIFT then TEST, then display TEST:CALIB with the up or down range
key. Press ENTER, select RUN, then enter the appropriate calibration code
(default: 002750).
6. Using the up or down range key, select CARD at the CAL:RUN prompt, then press
ENTER.
7. Set the display value to the cold calibration temperature (°C) you measured in Step
3, then press ENTER to complete Model 7700 calibration.