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Troubleshooting and Service
11.6.9. MOTHERBOARD
11.6.9.1. A/D FUNCTIONS
11.6.9.2. ANALOG OUTPUTS: CURRENT LOOP
Table 11-7: Analog Output Test Function - Nominal Values Current Outputs
STEP
1
2
3
4
5
6
212
Teledyne API T802 Paramagnetic O
The simplest method to check the operation of the A-to-D converter on the
motherboard is to use the Signal I/O function under the DIAG menu to check the
two A/D reference voltages and input signals that can be easily measured with a
voltmeter.
1. Use the Signal I/O function (See Section 11.1.3 and Appendix A) to view the
value of REF_4096_MV and REF_GND.
If both are within 3 mV of nominal (4096 and 0), and are stable, ±0.2 mV
then the basic A/D is functioning properly. If not then the motherboard is
bad.
2. Choose a parameter in the Signal I/O function such as
SAMPLE_PRESSURE or SAMPLE_FLOW.
Compare these voltages at their origin (see interconnect drawing PN
06407 and interconnect list PN 06294 in Appendix D) with the voltage
displayed through the signal I/O function.
If the wiring is intact but there is a large difference between the measured
and displayed voltage (±10 mV) then the motherboard is bad.
To verify that the analog outputs with the optional current mode output are
working properly, connect a 250 ohm resistor across the outputs and use a
voltmeter to measure the output as described in Section 5.9.3.6.
For each step the output should be within 1% of the nominal value listed in the
table below.
%
CURRENT
0
2 mA
20
5.6
40
9.2
60
12.8
80
16.4
100
20
OUTPUT RANGE
2 -20
NOMINAL OUTPUT VALUES
V(250 OHMS)
0.5V
1.4
2.3
3.2
4.1
5
Analyzer Operation Manual
2
4 -20
CURRENT
V(250 OHMS)
4
1
7.2
1.8
10.4
2.6
13.6
3.4
16.8
4.2
20
5
07275B DCN6418
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