P
AGE
50
5.2.2 CAL2 MAIN CALIBRATION
This procedure determines and saves calibration values which correct for component varia-
tions relating to the input measuring function of the instrument. CAL2 is the only
calibration required for the volt and millivolt inputs. Additional calibration procedures are
required for thermocouple and RTD inputs.
A 50.00
±
.01mVDC source is required for calibrating. In addition make sure that JU1 on the
Processor board is in the “non volt” position. See Appendix A-2 (page 65).
With CAL2 displayed, press and hold the DOWN key, then press the SCROLL key. Release
both keys and the instrument will display hLd1. Short the input terminals 1 and 3 or apply
0.00
±
mV to the input. Depress the DOWN key; dELy will appear for up to ten seconds,
then SCAn will appear for up to ten seconds. A calibration reference number, which should
be 0,
±
50, should then appear. With a number within tolerance display, connect a 50.00
±
.01mV source to the input terminals. Press the DOWN key and deLy will be displayed for
ten seconds and the SCAn for ten seconds. Then CAL2 will reappear. If there is a problem,
the appropriate error code will be displayed. Restore JU1 to the position necessary for the
input type.
If the calibration reference number falls outside the 0,
±
50 tolerance, depress the SCROLL
key and CAL2 will be displayed. Depress the DOWN key and perform the calibration once
more. Repeat the calibration until the number falls within the tolerance limits. If the calibra-
tion number remains outside these limits, check the connections to the test equipment and try
the calibration again. If the number still does not approach the tolerance limits contact an
Applications Service Engineer at the factory or a local
representative.
Error Recovery - see 5.4 (page 56) for details. However, be sure that the millivolt source is
securely connected, functioning properly and the polarity is correct. Press the DOWN key to
bring the instrument back to dELy and try the calibration again. The calibration can be exited
at anytime. hLd1 or the reference number is displayed by pressing the SCROLL key.
CAL2 QUICK CALIBRATION
This routine will allow the operator to execute a rough calibration on their unit via the keypad
with no other equipment or disturbance to established wiring. It is intended to provide a partial
recovery from a calibration corruption where the necessary equipment indicated in CAL 2-5
may not be available. Is should be noted that this is not intended as a substitution to the main
calibration procedure described earlier and may considerably deter from the accuracy of the
instrument.
With CAL2 displayed, press and hold the DOWN ARROW key, then press the SCROLL key.
Release both keys and the instrument will display hLd1. Press and hold the UP ARROW key,
then press the SCROLL key. The display will momentarily blank and then CAL1 will be
displayed. Release both keys and depress the UP ARROW key. CAL will be displayed.
5.2.3 CAL 3 COLD JUNCTION COMPENSATION
This procedure determines and saves calibration values which correct component variations
relating to the cold junction compensation. This calibration must be preceeded by CAL2 the
main calibration, to properly calibrate the instrument. These two calibrations are the only
ones needed for proper operation with a thermocouple input.
For test equipment: one type J thermocouple and one mercury thermometer accurate to
±
.25 degrees C or equivalent is required. Allow 30 minutes of warm up time, with the
thermocouple connected, before proceeding with calibration.
With CAL3 displayed, depress and hold the DOWN key. Then press the SCROLL key and
the unit will display hoLd. Release both keys. Connect the J thermocouple to the input
terminals and place thermometer at the back of the unit. Press the DOWN key and deLy will
