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Teledyne API - Model T200H/T200M Operation Manual Troubleshooting & Repair
247
7.5.10. MOTHERBOARD
7.5.10.1. 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 (Section 4.13.2 Appendix D), view the value of
REF_4096_MV and REF_GND. If both are within 3 mV of their nominal values
(4096 and 0) and are stable to within ±0.5 mV, the basic A/D converter is function-
ing properly. If these values fluctuate largely or are off by more than 3 mV, 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
(see 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.
7.5.10.2. 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 4.13.3.
For each of t
he steps, taking into account any offset that may have been programmed
into the channel (Section 4.13.5.4), the output should be within 1% of the nominal value
listed in t
he table below 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 7-9: 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
07270B DCN6512