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M400E Ozone Analyzer Operator’s Manual General Troubleshooting & Repair of the M400E Analyzer
13.7.7.2. 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 13.1.3 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
PHOTO_LAMP_DRIVE or SAMPLE_FLOW.
Compare these voltages at their origin (see the interconnect drawing and interconnect list 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.
13.7.7.3. Status Outputs
To test the status output electronics:
1. Connect a jumper between the “D“pin and the “” pin on the status output connector.
2. Connect a 1000 ohm resistor between the “+” pin and the pin for the status output that is being tested.
3. Connect a voltmeter between the “” pin and the pin of the output being tested (see table below).
4. Under the
DIAG SIGNAL I/O menu (See Section13.1.3), scroll through the inputs and outputs until
you get to the output in question.
5. Alternately, turn on and off the output noting the voltage on the voltmeter.
It should vary between 0 volts for ON and 5 volts for OFF.
Table 13-10: Status Outputs Check
PIN (LEFT TO RIGHT) STATUS
1
ST_SYSTEM_OK
2
ST_CONC_VALID
3
ST_HIGH_RANGE
4
ST_ZERO_CAL
5
ST_SPAN_CAL
6
ST_DIAGMODE
7
ST_FLOW_ALARM
8
ST_PRESS_ALARM
04315 Rev. C1 251