Troubleshooting and Service
Teledyne API – Model T300/T300M CO Analyzer
266
11.5.8.
MOTHERBOARD
11.5.8.1.
A/D FUNCTIONS
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, ±0.5 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,
SAMPLE_FLOW, CO_MEASURE or CO_REFERENCE.
•
Compare these voltages at their origin (see interconnect drawing, P/N 04215
and interconnect list, P/N 04216) 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.
See also Sections 5.9.1 and 11.1.3.
11.5.8.2.
TEST CHANNEL / ANALOG OUTPUTS VOLTAGE
The
ANALOG OUTPUT
submenu, located under the
SETUP
à
MORE
à
DIAG
menu is used to verify that the T300/T300M Analyzer’s analog outputs are working
properly. The test generates a signal on functioning outputs simultaneously as shown in
the following table. (See also Section 5.9.2).
Table 11-10:
Analog Output Test Function - Nominal Values Voltage Outputs
FULL SCALE OUTPUT OF VOLTAGE RANGE
(see Section 5.9.3.1)
100MV
1V
5V
10V
STEP
%
NOMINAL OUTPUT VOLTAGE
1
0
0
0
0
0
2
20
20 mV
0.2
1
2
3
40
40 mV
0.4
2
4
4
60
60 mV
0.6
3
6
5
80
80 mV
0.8
4
8
6
100
100 mV
1.0
5
10
For each of the steps the output should be within 1% of the nominal value listed in the
table below except for the 0% step, which should be within 0mV ±2 mV. Make sure
you take into account any offset that may have been programmed into channel (see
Section 5.9.3.9).
If one or more of the steps fails to be within these ranges, it is likely that there has been
a failure of either or both of the DACs and their associated circuitry on the motherboard.
To perform the test connect a voltmeter to the output in question and perform an analog
output step test as follows:
06864D DCN7562
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