Teledyne API - Model T200H/T200M Operation Manual
Troubleshooting & Service
245
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 the 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 the 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
07270D DCN7141