Teledyne 6200T - Sulfides Analyzer - Manual (Page 254)

Troubleshooting Model 6200T Total Sulfur Analyzer
254 Teledyne Analytical Instruments
12.6.7. Motherboard
12.6.7.1. A/D functions
A basic check of the analog to digital (A/D) converter operation on the motherboard is
to use the Signal I/O function under the DIAG menu. Check the following two A/D
reference voltages and input signals that can be easily measured with a voltmeter. Using
the Signal I/O function (refer to Section 5.9.1 and Appendix D), view the value of
REF_4096_MV and REF_GND.
 The nominal value for REF_4096_MV is 4096 mV  10 mV.
 The nominal value for REF_GND is 0 mV  3 mV, respectively, of their
nominal values (4096 and 0) and are
 If these signals are stable to within ±0.5 mV, the basic A/D converter is
functioning properly.
 If these values fluctuate largely or are off by more than specified above, one
or more of the analog circuits may be overloaded or the motherboard may
be faulty.
 Choose one parameter in the Signal I/O function such as
SAMPLE_PRESSURE (refer to previous section on how to measure it).
Compare its actual voltage with the voltage displayed through the SIGNAL
I/O function. If the wiring is intact but there is a difference of more than
±10 mV between the measured and displayed voltage, the motherboard may
be faulty.
12.6.7.2. Analog Output Voltages
To verify that the analog outputs are working properly, connect a voltmeter to the output
in question and perform an analog output step test as described in Section 5.9.2.
For each of the steps, taking into account any offset that may have been programmed
into the channel (refer to Section 5.9.3.4), the output should be within 1% of the nominal
value listed in the Table 11-7 except for the 0% step, which should be within 2-3 mV. If
one or more of the steps is outside of this range, a failure of one or both D/A converters
and their associated circuitry on the motherboard is likely.
Table 12-7: Analog Output Test Function - Nominal Values
FULL SCALE OUTPUT VOLTAGE
100MV 1V 5V 10V *
STEP % NOMINAL OUTPUT VOLTAGE
1 0 0 mV 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
* Increase the Analog Out (AOUT) Cal Limits in the DIAG>Analog I/O Config menu.
12.6.7.3. Status Outputs
The procedure below can be used to test the Status outputs.