FIGURE 4.2- ANALOG OUTPUT JUMPERS
5.3 A/D - D/A Calibration Procedure
This procedure should be performed whenever a circuit board assembly is exchanged or whenever the analog output voltage range is changed.
To calibrate the ADC, do the following:
1.Press SETUP-DIAG.
2.Enter Diagnostic password and press NEXT until D/A CALIBRATION appears in the display and press ENTR.
3.Press ADC to perform the A/D Cal.
4.The M450H display will read "ADJUST ZERO:A/D=xx.x MV.” Put the probe of a voltmeter between TP3(AGND) and TP9(DAC #0) on the top of the V/F card.
5.The value displayed by the voltmeter should be close(+/- 20 mV) to the value on the M450H display. If they are not close then the V/F card has probably been configured improperly.
6.Adjust the Zero pot(R27) on the V/F card until the value on the M450H display matches the value on the voltmeter to within +/- 2 mV. Note that when adjusting R27, the value on the M450H display will change, the value on the voltmeter will remain constant.
7.Press ENTR.
8.The M450H display will now read "ADJUST GAIN:A/D=xx.x MV.”
9.Adjust the Span Pot (R31) on the V/F card until the value on the M450H display matches the value on the voltmeter to within +/- 2 mV.
10.Press ENTR.
11.The ADC is now calibrated and the M450H will automatically calibrate all the DAC's. This process takes only a few seconds.
12.Press EXIT 3 times to return to the sample menu.
P/N 02826B1 Teledyne API Model 450H O3 Monitor Instruction Manual - Page 42
