Marathon Computer V3.5 user manual Calibration Of The Thermocouple Board

Maintence and Troubleshooting

Unipro 3.5

Preparing For Calibration

Before placing the UNIPRO into calibration mode, check to be sure that for each input:

The proper thermocouple type has been selected, and

Cold Junction compensation has been selected, if required. Cold Junction compensation can be selected by using the [Setup] key. The option is below the corresponding input type selection.

The UNIPRO is placed into calibration mode by connecting a jumper from TBD-17 to TBD-18. To make sure of the integrity of the calibration factors, power should be applied to the UNIPRO before this jumper is installed and not removed until after this jumper has been removed. The UNIPRO should be operating for at least 30 minutes before calibration to make sure that input circuits have stabilized.

For each input of the UNIPRO, follow the calibration procedure by the type of input board installed for that input. Once an input has been calibrated, be sure to press the [Enter] key to make sure that the latest calibration factors are stored.

Calibration Of The Thermocouple Board

This calibration procedure assumes that a thermocouple has been selected and internal cold junction compensation is being used. If this is not true, follow the procedure for the auxiliary board using a 0 to 40 millivolt signal. The calibration procedure is as follows:

Connect the input to be calibrated to a junction compensated calibrator (IE: Biddle Instrument Co. Versa-Cal Calibrator) using the proper extension wire for the thermocouple type selected.

Rev. 11.00

December 30, 1995