Keithley 2700, Service Manual

Page: 70 / 174

2-22 Calibration
Model 7700 calibration
The following procedures calibrate the temperature sensors on the Model 7700 plug-in
modules.
NOTE For additional information about the Keithley modules, refer to the appropriate
appendix in the Model 2700 User’s Manual.
Recommended test equipment
In order to calibrate the Model 7700, you will need equipment summarized in Table 2-14 .
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 2700 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 possi-
ble to minimize card heating that could affect calibration accuracy. Allow the
Model 2700 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” above).
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 surface at
the center of the card with an RTD sensor.
4. Press in and hold the Model 2700 OPEN key while turning on the power.
Table 2-14
Recommended equipment for Model 7700 calibration
Digital Thermometer:
18 to 28˚C, ±0.1˚C
Keithley 7797 Calibration/Extender Board